summaryrefslogtreecommitdiffstats
path: root/modules/brotli/dec/decode.c
diff options
context:
space:
mode:
Diffstat (limited to 'modules/brotli/dec/decode.c')
-rw-r--r--modules/brotli/dec/decode.c2262
1 files changed, 2262 insertions, 0 deletions
diff --git a/modules/brotli/dec/decode.c b/modules/brotli/dec/decode.c
new file mode 100644
index 000000000..d184f24cb
--- /dev/null
+++ b/modules/brotli/dec/decode.c
@@ -0,0 +1,2262 @@
+/* Copyright 2013 Google Inc. All Rights Reserved.
+
+ Distributed under MIT license.
+ See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+
+#include "./decode.h"
+
+#ifdef __ARM_NEON__
+#include <arm_neon.h>
+#endif
+
+#include <stdlib.h> /* free, malloc */
+#include <string.h> /* memcpy, memset */
+
+#include "./bit_reader.h"
+#include "./context.h"
+#include "./dictionary.h"
+#include "./huffman.h"
+#include "./port.h"
+#include "./prefix.h"
+#include "./state.h"
+#include "./transform.h"
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+#define BROTLI_FAILURE(CODE) (BROTLI_DUMP(), CODE)
+
+#define BROTLI_LOG_UINT(name) \
+ BROTLI_LOG(("[%s] %s = %lu\n", __func__, #name, (unsigned long)(name)))
+#define BROTLI_LOG_ARRAY_INDEX(array_name, idx) \
+ BROTLI_LOG(("[%s] %s[%lu] = %lu\n", __func__, #array_name, \
+ (unsigned long)(idx), (unsigned long)array_name[idx]))
+
+static const uint32_t kDefaultCodeLength = 8;
+static const uint32_t kCodeLengthRepeatCode = 16;
+static const uint32_t kNumLiteralCodes = 256;
+static const uint32_t kNumInsertAndCopyCodes = 704;
+static const uint32_t kNumBlockLengthCodes = 26;
+static const int kLiteralContextBits = 6;
+static const int kDistanceContextBits = 2;
+
+#define HUFFMAN_TABLE_BITS 8U
+#define HUFFMAN_TABLE_MASK 0xff
+
+#define CODE_LENGTH_CODES 18
+static const uint8_t kCodeLengthCodeOrder[CODE_LENGTH_CODES] = {
+ 1, 2, 3, 4, 0, 5, 17, 6, 16, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+};
+
+/* Static prefix code for the complex code length code lengths. */
+static const uint8_t kCodeLengthPrefixLength[16] = {
+ 2, 2, 2, 3, 2, 2, 2, 4, 2, 2, 2, 3, 2, 2, 2, 4,
+};
+
+static const uint8_t kCodeLengthPrefixValue[16] = {
+ 0, 4, 3, 2, 0, 4, 3, 1, 0, 4, 3, 2, 0, 4, 3, 5,
+};
+
+#define NUM_DISTANCE_SHORT_CODES 16
+
+BrotliState* BrotliCreateState(
+ brotli_alloc_func alloc_func, brotli_free_func free_func, void* opaque) {
+ BrotliState* state = 0;
+ if (!alloc_func && !free_func) {
+ state = (BrotliState*)malloc(sizeof(BrotliState));
+ } else if (alloc_func && free_func) {
+ state = (BrotliState*)alloc_func(opaque, sizeof(BrotliState));
+ }
+ if (state == 0) {
+ BROTLI_DUMP();
+ return 0;
+ }
+ BrotliStateInitWithCustomAllocators(state, alloc_func, free_func, opaque);
+ state->error_code = BROTLI_NO_ERROR;
+ return state;
+}
+
+/* Deinitializes and frees BrotliState instance. */
+void BrotliDestroyState(BrotliState* state) {
+ if (!state) {
+ return;
+ } else {
+ brotli_free_func free_func = state->free_func;
+ void* opaque = state->memory_manager_opaque;
+ BrotliStateCleanup(state);
+ free_func(opaque, state);
+ }
+}
+
+/* Saves error code and converts it to BrotliResult */
+static BROTLI_NOINLINE BrotliResult SaveErrorCode(
+ BrotliState* s, BrotliErrorCode e) {
+ s->error_code = (int)e;
+ switch (e) {
+ case BROTLI_SUCCESS: return BROTLI_RESULT_SUCCESS;
+ case BROTLI_NEEDS_MORE_INPUT: return BROTLI_RESULT_NEEDS_MORE_INPUT;
+ case BROTLI_NEEDS_MORE_OUTPUT: return BROTLI_RESULT_NEEDS_MORE_OUTPUT;
+ default: return BROTLI_RESULT_ERROR;
+ }
+}
+
+/* Decodes a number in the range [9..24], by reading 1 - 7 bits.
+ Precondition: bit-reader accumulator has at least 7 bits. */
+static uint32_t DecodeWindowBits(BrotliBitReader* br) {
+ uint32_t n;
+ BrotliTakeBits(br, 1, &n);
+ if (n == 0) {
+ return 16;
+ }
+ BrotliTakeBits(br, 3, &n);
+ if (n != 0) {
+ return 17 + n;
+ }
+ BrotliTakeBits(br, 3, &n);
+ if (n != 0) {
+ return 8 + n;
+ }
+ return 17;
+}
+
+static BROTLI_INLINE void memmove16(uint8_t* dst, uint8_t* src) {
+#if defined(__ARM_NEON__)
+ vst1q_u8(dst, vld1q_u8(src));
+#else
+ uint32_t buffer[4];
+ memcpy(buffer, src, 16);
+ memcpy(dst, buffer, 16);
+#endif
+}
+
+/* Decodes a number in the range [0..255], by reading 1 - 11 bits. */
+static BROTLI_NOINLINE BrotliErrorCode DecodeVarLenUint8(BrotliState* s,
+ BrotliBitReader* br, uint32_t* value) {
+ uint32_t bits;
+ switch (s->substate_decode_uint8) {
+ case BROTLI_STATE_DECODE_UINT8_NONE:
+ if (PREDICT_FALSE(!BrotliSafeReadBits(br, 1, &bits))) {
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ if (bits == 0) {
+ *value = 0;
+ return BROTLI_SUCCESS;
+ }
+ /* No break, transit to the next state. */
+
+ case BROTLI_STATE_DECODE_UINT8_SHORT:
+ if (PREDICT_FALSE(!BrotliSafeReadBits(br, 3, &bits))) {
+ s->substate_decode_uint8 = BROTLI_STATE_DECODE_UINT8_SHORT;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ if (bits == 0) {
+ *value = 1;
+ s->substate_decode_uint8 = BROTLI_STATE_DECODE_UINT8_NONE;
+ return BROTLI_SUCCESS;
+ }
+ /* Use output value as a temporary storage. It MUST be persisted. */
+ *value = bits;
+ /* No break, transit to the next state. */
+
+ case BROTLI_STATE_DECODE_UINT8_LONG:
+ if (PREDICT_FALSE(!BrotliSafeReadBits(br, *value, &bits))) {
+ s->substate_decode_uint8 = BROTLI_STATE_DECODE_UINT8_LONG;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ *value = (1U << *value) + bits;
+ s->substate_decode_uint8 = BROTLI_STATE_DECODE_UINT8_NONE;
+ return BROTLI_SUCCESS;
+
+ default:
+ return BROTLI_FAILURE(BROTLI_ERROR_UNREACHABLE);
+ }
+}
+
+/* Decodes a metablock length and flags by reading 2 - 31 bits. */
+static BrotliErrorCode BROTLI_NOINLINE DecodeMetaBlockLength(
+ BrotliState* s, BrotliBitReader* br) {
+ uint32_t bits;
+ int i;
+ for (;;) {
+ switch (s->substate_metablock_header) {
+ case BROTLI_STATE_METABLOCK_HEADER_NONE:
+ if (!BrotliSafeReadBits(br, 1, &bits)) {
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ s->is_last_metablock = (uint8_t)bits;
+ s->meta_block_remaining_len = 0;
+ s->is_uncompressed = 0;
+ s->is_metadata = 0;
+ if (!s->is_last_metablock) {
+ s->substate_metablock_header = BROTLI_STATE_METABLOCK_HEADER_NIBBLES;
+ break;
+ }
+ s->substate_metablock_header = BROTLI_STATE_METABLOCK_HEADER_EMPTY;
+ /* No break, transit to the next state. */
+
+ case BROTLI_STATE_METABLOCK_HEADER_EMPTY:
+ if (!BrotliSafeReadBits(br, 1, &bits)) {
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ if (bits) {
+ s->substate_metablock_header = BROTLI_STATE_METABLOCK_HEADER_NONE;
+ return BROTLI_SUCCESS;
+ }
+ s->substate_metablock_header = BROTLI_STATE_METABLOCK_HEADER_NIBBLES;
+ /* No break, transit to the next state. */
+
+ case BROTLI_STATE_METABLOCK_HEADER_NIBBLES:
+ if (!BrotliSafeReadBits(br, 2, &bits)) {
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ s->size_nibbles = (uint8_t)(bits + 4);
+ s->loop_counter = 0;
+ if (bits == 3) {
+ s->is_metadata = 1;
+ s->substate_metablock_header = BROTLI_STATE_METABLOCK_HEADER_RESERVED;
+ break;
+ }
+ s->substate_metablock_header = BROTLI_STATE_METABLOCK_HEADER_SIZE;
+ /* No break, transit to the next state. */
+
+ case BROTLI_STATE_METABLOCK_HEADER_SIZE:
+ i = s->loop_counter;
+ for (; i < s->size_nibbles; ++i) {
+ if (!BrotliSafeReadBits(br, 4, &bits)) {
+ s->loop_counter = i;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ if (i + 1 == s->size_nibbles && s->size_nibbles > 4 && bits == 0) {
+ return BROTLI_FAILURE(BROTLI_ERROR_FORMAT_EXUBERANT_NIBBLE);
+ }
+ s->meta_block_remaining_len |= (int)(bits << (i * 4));
+ }
+ s->substate_metablock_header =
+ BROTLI_STATE_METABLOCK_HEADER_UNCOMPRESSED;
+ /* No break, transit to the next state. */
+
+ case BROTLI_STATE_METABLOCK_HEADER_UNCOMPRESSED:
+ if (!s->is_last_metablock) {
+ if (!BrotliSafeReadBits(br, 1, &bits)) {
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ s->is_uncompressed = (uint8_t)bits;
+ }
+ ++s->meta_block_remaining_len;
+ s->substate_metablock_header = BROTLI_STATE_METABLOCK_HEADER_NONE;
+ return BROTLI_SUCCESS;
+
+ case BROTLI_STATE_METABLOCK_HEADER_RESERVED:
+ if (!BrotliSafeReadBits(br, 1, &bits)) {
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ if (bits != 0) {
+ return BROTLI_FAILURE(BROTLI_ERROR_FORMAT_RESERVED);
+ }
+ s->substate_metablock_header = BROTLI_STATE_METABLOCK_HEADER_BYTES;
+ /* No break, transit to the next state. */
+
+ case BROTLI_STATE_METABLOCK_HEADER_BYTES:
+ if (!BrotliSafeReadBits(br, 2, &bits)) {
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ if (bits == 0) {
+ s->substate_metablock_header = BROTLI_STATE_METABLOCK_HEADER_NONE;
+ return BROTLI_SUCCESS;
+ }
+ s->size_nibbles = (uint8_t)bits;
+ s->substate_metablock_header = BROTLI_STATE_METABLOCK_HEADER_METADATA;
+ /* No break, transit to the next state. */
+
+ case BROTLI_STATE_METABLOCK_HEADER_METADATA:
+ i = s->loop_counter;
+ for (; i < s->size_nibbles; ++i) {
+ if (!BrotliSafeReadBits(br, 8, &bits)) {
+ s->loop_counter = i;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ if (i + 1 == s->size_nibbles && s->size_nibbles > 1 && bits == 0) {
+ return BROTLI_FAILURE(BROTLI_ERROR_FORMAT_EXUBERANT_META_NIBBLE);
+ }
+ s->meta_block_remaining_len |= (int)(bits << (i * 8));
+ }
+ ++s->meta_block_remaining_len;
+ s->substate_metablock_header = BROTLI_STATE_METABLOCK_HEADER_NONE;
+ return BROTLI_SUCCESS;
+
+ default:
+ return BROTLI_FAILURE(BROTLI_ERROR_UNREACHABLE);
+ }
+ }
+}
+
+/* Decodes the Huffman code.
+ This method doesn't read data from the bit reader, BUT drops the amount of
+ bits that correspond to the decoded symbol.
+ bits MUST contain at least 15 (BROTLI_HUFFMAN_MAX_CODE_LENGTH) valid bits. */
+static BROTLI_INLINE uint32_t DecodeSymbol(uint32_t bits,
+ const HuffmanCode* table,
+ BrotliBitReader* br) {
+ table += bits & HUFFMAN_TABLE_MASK;
+ if (table->bits > HUFFMAN_TABLE_BITS) {
+ uint32_t nbits = table->bits - HUFFMAN_TABLE_BITS;
+ BrotliDropBits(br, HUFFMAN_TABLE_BITS);
+ table += table->value;
+ table += (bits >> HUFFMAN_TABLE_BITS) & BitMask(nbits);
+ }
+ BrotliDropBits(br, table->bits);
+ return table->value;
+}
+
+/* Reads and decodes the next Huffman code from bit-stream.
+ This method peeks 16 bits of input and drops 0 - 15 of them. */
+static BROTLI_INLINE uint32_t ReadSymbol(const HuffmanCode* table,
+ BrotliBitReader* br) {
+ return DecodeSymbol(BrotliGet16BitsUnmasked(br), table, br);
+}
+
+/* Same as DecodeSymbol, but it is known that there is less than 15 bits of
+ input are currently available. */
+static BROTLI_NOINLINE int SafeDecodeSymbol(const HuffmanCode* table,
+ BrotliBitReader* br,
+ uint32_t* result) {
+ uint32_t val;
+ uint32_t available_bits = BrotliGetAvailableBits(br);
+ if (available_bits == 0) {
+ if (table->bits == 0) {
+ *result = table->value;
+ return 1;
+ }
+ return 0; /* No valid bits at all. */
+ }
+ val = (uint32_t)BrotliGetBitsUnmasked(br);
+ table += val & HUFFMAN_TABLE_MASK;
+ if (table->bits <= HUFFMAN_TABLE_BITS) {
+ if (table->bits <= available_bits) {
+ BrotliDropBits(br, table->bits);
+ *result = table->value;
+ return 1;
+ } else {
+ return 0; /* Not enough bits for the first level. */
+ }
+ }
+ if (available_bits <= HUFFMAN_TABLE_BITS) {
+ return 0; /* Not enough bits to move to the second level. */
+ }
+
+ /* Speculatively drop HUFFMAN_TABLE_BITS. */
+ val = (val & BitMask(table->bits)) >> HUFFMAN_TABLE_BITS;
+ available_bits -= HUFFMAN_TABLE_BITS;
+ table += table->value + val;
+ if (available_bits < table->bits) {
+ return 0; /* Not enough bits for the second level. */
+ }
+
+ BrotliDropBits(br, HUFFMAN_TABLE_BITS + table->bits);
+ *result = table->value;
+ return 1;
+}
+
+static BROTLI_INLINE int SafeReadSymbol(const HuffmanCode* table,
+ BrotliBitReader* br,
+ uint32_t* result) {
+ uint32_t val;
+ if (PREDICT_TRUE(BrotliSafeGetBits(br, 15, &val))) {
+ *result = DecodeSymbol(val, table, br);
+ return 1;
+ }
+ return SafeDecodeSymbol(table, br, result);
+}
+
+/* Makes a look-up in first level Huffman table. Peeks 8 bits. */
+static BROTLI_INLINE void PreloadSymbol(int safe,
+ const HuffmanCode* table,
+ BrotliBitReader* br,
+ uint32_t* bits,
+ uint32_t* value) {
+ if (safe) {
+ return;
+ }
+ table += BrotliGetBits(br, HUFFMAN_TABLE_BITS);
+ *bits = table->bits;
+ *value = table->value;
+}
+
+/* Decodes the next Huffman code using data prepared by PreloadSymbol.
+ Reads 0 - 15 bits. Also peeks 8 following bits. */
+static BROTLI_INLINE uint32_t ReadPreloadedSymbol(const HuffmanCode* table,
+ BrotliBitReader* br,
+ uint32_t* bits,
+ uint32_t* value) {
+ uint32_t result = *value;
+ if (PREDICT_FALSE(*bits > HUFFMAN_TABLE_BITS)) {
+ uint32_t val = BrotliGet16BitsUnmasked(br);
+ const HuffmanCode* ext = table + (val & HUFFMAN_TABLE_MASK) + *value;
+ uint32_t mask = BitMask((*bits - HUFFMAN_TABLE_BITS));
+ BrotliDropBits(br, HUFFMAN_TABLE_BITS);
+ ext += (val >> HUFFMAN_TABLE_BITS) & mask;
+ BrotliDropBits(br, ext->bits);
+ result = ext->value;
+ } else {
+ BrotliDropBits(br, *bits);
+ }
+ PreloadSymbol(0, table, br, bits, value);
+ return result;
+}
+
+static BROTLI_INLINE uint32_t Log2Floor(uint32_t x) {
+ uint32_t result = 0;
+ while (x) {
+ x >>= 1;
+ ++result;
+ }
+ return result;
+}
+
+/* Reads (s->symbol + 1) symbols.
+ Totally 1..4 symbols are read, 1..10 bits each.
+ The list of symbols MUST NOT contain duplicates.
+ */
+static BrotliErrorCode ReadSimpleHuffmanSymbols(uint32_t alphabet_size,
+ BrotliState* s) {
+ /* max_bits == 1..10; symbol == 0..3; 1..40 bits will be read. */
+ BrotliBitReader* br = &s->br;
+ uint32_t max_bits = Log2Floor(alphabet_size - 1);
+ uint32_t i = s->sub_loop_counter;
+ uint32_t num_symbols = s->symbol;
+ while (i <= num_symbols) {
+ uint32_t v;
+ if (PREDICT_FALSE(!BrotliSafeReadBits(br, max_bits, &v))) {
+ s->sub_loop_counter = i;
+ s->substate_huffman = BROTLI_STATE_HUFFMAN_SIMPLE_READ;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ if (v >= alphabet_size) {
+ return BROTLI_FAILURE(BROTLI_ERROR_FORMAT_SIMPLE_HUFFMAN_ALPHABET);
+ }
+ s->symbols_lists_array[i] = (uint16_t)v;
+ BROTLI_LOG_UINT(s->symbols_lists_array[i]);
+ ++i;
+ }
+
+ for (i = 0; i < num_symbols; ++i) {
+ uint32_t k = i + 1;
+ for (; k <= num_symbols; ++k) {
+ if (s->symbols_lists_array[i] == s->symbols_lists_array[k]) {
+ return BROTLI_FAILURE(BROTLI_ERROR_FORMAT_SIMPLE_HUFFMAN_SAME);
+ }
+ }
+ }
+
+ return BROTLI_SUCCESS;
+}
+
+/* Process single decoded symbol code length:
+ A) reset the repeat variable
+ B) remember code length (if it is not 0)
+ C) extend corredponding index-chain
+ D) reduce the huffman space
+ E) update the histogram
+ */
+static BROTLI_INLINE void ProcessSingleCodeLength(uint32_t code_len,
+ uint32_t* symbol, uint32_t* repeat, uint32_t* space,
+ uint32_t* prev_code_len, uint16_t* symbol_lists,
+ uint16_t* code_length_histo, int* next_symbol) {
+ *repeat = 0;
+ if (code_len != 0) { /* code_len == 1..15 */
+ symbol_lists[next_symbol[code_len]] = (uint16_t)(*symbol);
+ next_symbol[code_len] = (int)(*symbol);
+ *prev_code_len = code_len;
+ *space -= 32768U >> code_len;
+ code_length_histo[code_len]++;
+ BROTLI_LOG(("[ReadHuffmanCode] code_length[%d] = %d\n", *symbol, code_len));
+ }
+ (*symbol)++;
+}
+
+/* Process repeated symbol code length.
+ A) Check if it is the extension of previous repeat sequence; if the decoded
+ value is not kCodeLengthRepeatCode, then it is a new symbol-skip
+ B) Update repeat variable
+ C) Check if operation is feasible (fits alphapet)
+ D) For each symbol do the same operations as in ProcessSingleCodeLength
+
+ PRECONDITION: code_len == kCodeLengthRepeatCode or kCodeLengthRepeatCode + 1
+ */
+static BROTLI_INLINE void ProcessRepeatedCodeLength(uint32_t code_len,
+ uint32_t repeat_delta, uint32_t alphabet_size, uint32_t* symbol,
+ uint32_t* repeat, uint32_t* space, uint32_t* prev_code_len,
+ uint32_t* repeat_code_len, uint16_t* symbol_lists,
+ uint16_t* code_length_histo, int* next_symbol) {
+ uint32_t old_repeat;
+ uint32_t new_len = 0;
+ if (code_len == kCodeLengthRepeatCode) {
+ new_len = *prev_code_len;
+ }
+ if (*repeat_code_len != new_len) {
+ *repeat = 0;
+ *repeat_code_len = new_len;
+ }
+ old_repeat = *repeat;
+ if (*repeat > 0) {
+ *repeat -= 2;
+ *repeat <<= code_len - 14U;
+ }
+ *repeat += repeat_delta + 3U;
+ repeat_delta = *repeat - old_repeat;
+ if (*symbol + repeat_delta > alphabet_size) {
+ BROTLI_DUMP();
+ *symbol = alphabet_size;
+ *space = 0xFFFFF;
+ return;
+ }
+ BROTLI_LOG(("[ReadHuffmanCode] code_length[%d..%d] = %d\n",
+ *symbol, *symbol + repeat_delta - 1, *repeat_code_len));
+ if (*repeat_code_len != 0) {
+ unsigned last = *symbol + repeat_delta;
+ int next = next_symbol[*repeat_code_len];
+ do {
+ symbol_lists[next] = (uint16_t)*symbol;
+ next = (int)*symbol;
+ } while (++(*symbol) != last);
+ next_symbol[*repeat_code_len] = next;
+ *space -= repeat_delta << (15 - *repeat_code_len);
+ code_length_histo[*repeat_code_len] =
+ (uint16_t)(code_length_histo[*repeat_code_len] + repeat_delta);
+ } else {
+ *symbol += repeat_delta;
+ }
+}
+
+/* Reads and decodes symbol codelengths. */
+static BrotliErrorCode ReadSymbolCodeLengths(
+ uint32_t alphabet_size, BrotliState* s) {
+ BrotliBitReader* br = &s->br;
+ uint32_t symbol = s->symbol;
+ uint32_t repeat = s->repeat;
+ uint32_t space = s->space;
+ uint32_t prev_code_len = s->prev_code_len;
+ uint32_t repeat_code_len = s->repeat_code_len;
+ uint16_t* symbol_lists = s->symbol_lists;
+ uint16_t* code_length_histo = s->code_length_histo;
+ int* next_symbol = s->next_symbol;
+ if (!BrotliWarmupBitReader(br)) {
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ while (symbol < alphabet_size && space > 0) {
+ const HuffmanCode* p = s->table;
+ uint32_t code_len;
+ if (!BrotliCheckInputAmount(br, BROTLI_SHORT_FILL_BIT_WINDOW_READ)) {
+ s->symbol = symbol;
+ s->repeat = repeat;
+ s->prev_code_len = prev_code_len;
+ s->repeat_code_len = repeat_code_len;
+ s->space = space;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ BrotliFillBitWindow16(br);
+ p += BrotliGetBitsUnmasked(br) &
+ BitMask(BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH);
+ BrotliDropBits(br, p->bits); /* Use 1..5 bits */
+ code_len = p->value; /* code_len == 0..17 */
+ if (code_len < kCodeLengthRepeatCode) {
+ ProcessSingleCodeLength(code_len, &symbol, &repeat, &space,
+ &prev_code_len, symbol_lists, code_length_histo, next_symbol);
+ } else { /* code_len == 16..17, extra_bits == 2..3 */
+ uint32_t repeat_delta =
+ (uint32_t)BrotliGetBitsUnmasked(br) & BitMask(code_len - 14U);
+ BrotliDropBits(br, code_len - 14U);
+ ProcessRepeatedCodeLength(code_len, repeat_delta, alphabet_size,
+ &symbol, &repeat, &space, &prev_code_len, &repeat_code_len,
+ symbol_lists, code_length_histo, next_symbol);
+ }
+ }
+ s->space = space;
+ return BROTLI_SUCCESS;
+}
+
+static BrotliErrorCode SafeReadSymbolCodeLengths(
+ uint32_t alphabet_size, BrotliState* s) {
+ BrotliBitReader* br = &s->br;
+ while (s->symbol < alphabet_size && s->space > 0) {
+ const HuffmanCode* p = s->table;
+ uint32_t code_len;
+ uint32_t bits = 0;
+ uint32_t available_bits = BrotliGetAvailableBits(br);
+ if (available_bits != 0) {
+ bits = (uint32_t)BrotliGetBitsUnmasked(br);
+ }
+ p += bits & BitMask(BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH);
+ if (p->bits > available_bits) goto pullMoreInput;
+ code_len = p->value; /* code_len == 0..17 */
+ if (code_len < kCodeLengthRepeatCode) {
+ BrotliDropBits(br, p->bits);
+ ProcessSingleCodeLength(code_len, &s->symbol, &s->repeat, &s->space,
+ &s->prev_code_len, s->symbol_lists, s->code_length_histo,
+ s->next_symbol);
+ } else { /* code_len == 16..17, extra_bits == 2..3 */
+ uint32_t extra_bits = code_len - 14U;
+ uint32_t repeat_delta = (bits >> p->bits) & BitMask(extra_bits);
+ if (available_bits < p->bits + extra_bits) goto pullMoreInput;
+ BrotliDropBits(br, p->bits + extra_bits);
+ ProcessRepeatedCodeLength(code_len, repeat_delta, alphabet_size,
+ &s->symbol, &s->repeat, &s->space, &s->prev_code_len,
+ &s->repeat_code_len, s->symbol_lists, s->code_length_histo,
+ s->next_symbol);
+ }
+ continue;
+
+pullMoreInput:
+ if (!BrotliPullByte(br)) {
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ }
+ return BROTLI_SUCCESS;
+}
+
+/* Reads and decodes 15..18 codes using static prefix code.
+ Each code is 2..4 bits long. In total 30..72 bits are used. */
+static BrotliErrorCode ReadCodeLengthCodeLengths(BrotliState* s) {
+ BrotliBitReader* br = &s->br;
+ uint32_t num_codes = s->repeat;
+ unsigned space = s->space;
+ uint32_t i = s->sub_loop_counter;
+ for (; i < CODE_LENGTH_CODES; ++i) {
+ const uint8_t code_len_idx = kCodeLengthCodeOrder[i];
+ uint32_t ix;
+ uint32_t v;
+ if (PREDICT_FALSE(!BrotliSafeGetBits(br, 4, &ix))) {
+ uint32_t available_bits = BrotliGetAvailableBits(br);
+ if (available_bits != 0) {
+ ix = BrotliGetBitsUnmasked(br) & 0xF;
+ } else {
+ ix = 0;
+ }
+ if (kCodeLengthPrefixLength[ix] > available_bits) {
+ s->sub_loop_counter = i;
+ s->repeat = num_codes;
+ s->space = space;
+ s->substate_huffman = BROTLI_STATE_HUFFMAN_COMPLEX;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ }
+ v = kCodeLengthPrefixValue[ix];
+ BrotliDropBits(br, kCodeLengthPrefixLength[ix]);
+ s->code_length_code_lengths[code_len_idx] = (uint8_t)v;
+ BROTLI_LOG_ARRAY_INDEX(s->code_length_code_lengths, code_len_idx);
+ if (v != 0) {
+ space = space - (32U >> v);
+ ++num_codes;
+ ++s->code_length_histo[v];
+ if (space - 1U >= 32U) {
+ /* space is 0 or wrapped around */
+ break;
+ }
+ }
+ }
+ if (!(num_codes == 1 || space == 0)) {
+ return BROTLI_FAILURE(BROTLI_ERROR_FORMAT_CL_SPACE);
+ }
+ return BROTLI_SUCCESS;
+}
+
+/* Decodes the Huffman tables.
+ There are 2 scenarios:
+ A) Huffman code contains only few symbols (1..4). Those symbols are read
+ directly; their code lengths are defined by the number of symbols.
+ For this scenario 4 - 45 bits will be read.
+
+ B) 2-phase decoding:
+ B.1) Small Huffman table is decoded; it is specified with code lengths
+ encoded with predefined entropy code. 32 - 74 bits are used.
+ B.2) Decoded table is used to decode code lengths of symbols in resulting
+ Huffman table. In worst case 3520 bits are read.
+*/
+static BrotliErrorCode ReadHuffmanCode(uint32_t alphabet_size,
+ HuffmanCode* table,
+ uint32_t* opt_table_size,
+ BrotliState* s) {
+ BrotliBitReader* br = &s->br;
+ /* Unnecessary masking, but might be good for safety. */
+ alphabet_size &= 0x3ff;
+ /* State machine */
+ switch (s->substate_huffman) {
+ case BROTLI_STATE_HUFFMAN_NONE:
+ if (!BrotliSafeReadBits(br, 2, &s->sub_loop_counter)) {
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ BROTLI_LOG_UINT(s->sub_loop_counter);
+ /* The value is used as follows:
+ 1 for simple code;
+ 0 for no skipping, 2 skips 2 code lengths, 3 skips 3 code lengths */
+ if (s->sub_loop_counter != 1) {
+ s->space = 32;
+ s->repeat = 0; /* num_codes */
+ memset(&s->code_length_histo[0], 0, sizeof(s->code_length_histo[0]) *
+ (BROTLI_HUFFMAN_MAX_CODE_LENGTH_CODE_LENGTH + 1));
+ memset(&s->code_length_code_lengths[0], 0,
+ sizeof(s->code_length_code_lengths));
+ s->substate_huffman = BROTLI_STATE_HUFFMAN_COMPLEX;
+ goto Complex;
+ }
+ /* No break, transit to the next state. */
+
+ case BROTLI_STATE_HUFFMAN_SIMPLE_SIZE:
+ /* Read symbols, codes & code lengths directly. */
+ if (!BrotliSafeReadBits(br, 2, &s->symbol)) { /* num_symbols */
+ s->substate_huffman = BROTLI_STATE_HUFFMAN_SIMPLE_SIZE;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ s->sub_loop_counter = 0;
+ /* No break, transit to the next state. */
+ case BROTLI_STATE_HUFFMAN_SIMPLE_READ: {
+ BrotliErrorCode result = ReadSimpleHuffmanSymbols(alphabet_size, s);
+ if (result != BROTLI_SUCCESS) {
+ return result;
+ }
+ /* No break, transit to the next state. */
+ }
+ case BROTLI_STATE_HUFFMAN_SIMPLE_BUILD: {
+ uint32_t table_size;
+ if (s->symbol == 3) {
+ uint32_t bits;
+ if (!BrotliSafeReadBits(br, 1, &bits)) {
+ s->substate_huffman = BROTLI_STATE_HUFFMAN_SIMPLE_BUILD;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ s->symbol += bits;
+ }
+ BROTLI_LOG_UINT(s->symbol);
+ table_size = BrotliBuildSimpleHuffmanTable(
+ table, HUFFMAN_TABLE_BITS, s->symbols_lists_array, s->symbol);
+ if (opt_table_size) {
+ *opt_table_size = table_size;
+ }
+ s->substate_huffman = BROTLI_STATE_HUFFMAN_NONE;
+ return BROTLI_SUCCESS;
+ }
+
+Complex: /* Decode Huffman-coded code lengths. */
+ case BROTLI_STATE_HUFFMAN_COMPLEX: {
+ uint32_t i;
+ BrotliErrorCode result = ReadCodeLengthCodeLengths(s);
+ if (result != BROTLI_SUCCESS) {
+ return result;
+ }
+ BrotliBuildCodeLengthsHuffmanTable(s->table,
+ s->code_length_code_lengths,
+ s->code_length_histo);
+ memset(&s->code_length_histo[0], 0, sizeof(s->code_length_histo));
+ for (i = 0; i <= BROTLI_HUFFMAN_MAX_CODE_LENGTH; ++i) {
+ s->next_symbol[i] = (int)i - (BROTLI_HUFFMAN_MAX_CODE_LENGTH + 1);
+ s->symbol_lists[(int)i - (BROTLI_HUFFMAN_MAX_CODE_LENGTH + 1)] = 0xFFFF;
+ }
+
+ s->symbol = 0;
+ s->prev_code_len = kDefaultCodeLength;
+ s->repeat = 0;
+ s->repeat_code_len = 0;
+ s->space = 32768;
+ s->substate_huffman = BROTLI_STATE_HUFFMAN_LENGTH_SYMBOLS;
+ /* No break, transit to the next state. */
+ }
+ case BROTLI_STATE_HUFFMAN_LENGTH_SYMBOLS: {
+ uint32_t table_size;
+ BrotliErrorCode result = ReadSymbolCodeLengths(alphabet_size, s);
+ if (result == BROTLI_NEEDS_MORE_INPUT) {
+ result = SafeReadSymbolCodeLengths(alphabet_size, s);
+ }
+ if (result != BROTLI_SUCCESS) {
+ return result;
+ }
+
+ if (s->space != 0) {
+ BROTLI_LOG(("[ReadHuffmanCode] space = %d\n", s->space));
+ return BROTLI_FAILURE(BROTLI_ERROR_FORMAT_HUFFMAN_SPACE);
+ }
+ table_size = BrotliBuildHuffmanTable(
+ table, HUFFMAN_TABLE_BITS, s->symbol_lists, s->code_length_histo);
+ if (opt_table_size) {
+ *opt_table_size = table_size;
+ }
+ s->substate_huffman = BROTLI_STATE_HUFFMAN_NONE;
+ return BROTLI_SUCCESS;
+ }
+
+ default:
+ return BROTLI_FAILURE(BROTLI_ERROR_UNREACHABLE);
+ }
+}
+
+/* Decodes a block length by reading 3..39 bits. */
+static BROTLI_INLINE uint32_t ReadBlockLength(const HuffmanCode* table,
+ BrotliBitReader* br) {
+ uint32_t code;
+ uint32_t nbits;
+ code = ReadSymbol(table, br);
+ nbits = kBlockLengthPrefixCode[code].nbits; /* nbits == 2..24 */
+ return kBlockLengthPrefixCode[code].offset + BrotliReadBits(br, nbits);
+}
+
+/* WARNING: if state is not BROTLI_STATE_READ_BLOCK_LENGTH_NONE, then
+ reading can't be continued with ReadBlockLength. */
+static BROTLI_INLINE int SafeReadBlockLength(BrotliState* s,
+ uint32_t* result,
+ const HuffmanCode* table,
+ BrotliBitReader* br) {
+ uint32_t index;
+ if (s->substate_read_block_length == BROTLI_STATE_READ_BLOCK_LENGTH_NONE) {
+ if (!SafeReadSymbol(table, br, &index)) {
+ return 0;
+ }
+ } else {
+ index = s->block_length_index;
+ }
+ {
+ uint32_t bits;
+ uint32_t nbits = kBlockLengthPrefixCode[index].nbits; /* nbits == 2..24 */
+ if (!BrotliSafeReadBits(br, nbits, &bits)) {
+ s->block_length_index = index;
+ s->substate_read_block_length = BROTLI_STATE_READ_BLOCK_LENGTH_SUFFIX;
+ return 0;
+ }
+ *result = kBlockLengthPrefixCode[index].offset + bits;
+ s->substate_read_block_length = BROTLI_STATE_READ_BLOCK_LENGTH_NONE;
+ return 1;
+ }
+}
+
+/* Transform:
+ 1) initialize list L with values 0, 1,... 255
+ 2) For each input element X:
+ 2.1) let Y = L[X]
+ 2.2) remove X-th element from L
+ 2.3) prepend Y to L
+ 2.4) append Y to output
+
+ In most cases max(Y) <= 7, so most of L remains intact.
+ To reduce the cost of initialization, we reuse L, remember the upper bound
+ of Y values, and reinitialize only first elements in L.
+
+ Most of input values are 0 and 1. To reduce number of branches, we replace
+ inner for loop with do-while.
+ */
+static BROTLI_NOINLINE void InverseMoveToFrontTransform(uint8_t* v,
+ uint32_t v_len, BrotliState* state) {
+ /* Reinitialize elements that could have been changed. */
+ uint32_t i = 4;
+ uint32_t upper_bound = state->mtf_upper_bound;
+ uint8_t* mtf = &state->mtf[4]; /* Make mtf[-1] addressable. */
+ /* Load endian-aware constant. */
+ const uint8_t b0123[4] = {0, 1, 2, 3};
+ uint32_t pattern;
+ memcpy(&pattern, &b0123, 4);
+
+ /* Initialize list using 4 consequent values pattern. */
+ *(uint32_t*)mtf = pattern;
+ do {
+ pattern += 0x04040404; /* Advance all 4 values by 4. */
+ *(uint32_t*)(mtf + i) = pattern;
+ i += 4;
+ } while (i <= upper_bound);
+
+ /* Transform the input. */
+ upper_bound = 0;
+ for (i = 0; i < v_len; ++i) {
+ int index = v[i];
+ uint8_t value = mtf[index];
+ upper_bound |= v[i];
+ v[i] = value;
+ mtf[-1] = value;
+ do {
+ index--;
+ mtf[index + 1] = mtf[index];
+ } while (index >= 0);
+ }
+ /* Remember amount of elements to be reinitialized. */
+ state->mtf_upper_bound = upper_bound;
+}
+
+/* Decodes a series of Huffman table using ReadHuffmanCode function. */
+static BrotliErrorCode HuffmanTreeGroupDecode(HuffmanTreeGroup* group,
+ BrotliState* s) {
+ if (s->substate_tree_group != BROTLI_STATE_TREE_GROUP_LOOP) {
+ s->next = group->codes;
+ s->htree_index = 0;
+ s->substate_tree_group = BROTLI_STATE_TREE_GROUP_LOOP;
+ }
+ while (s->htree_index < group->num_htrees) {
+ uint32_t table_size;
+ BrotliErrorCode result =
+ ReadHuffmanCode(group->alphabet_size, s->next, &table_size, s);
+ if (result != BROTLI_SUCCESS) return result;
+ group->htrees[s->htree_index] = s->next;
+ s->next += table_size;
+ ++s->htree_index;
+ }
+ s->substate_tree_group = BROTLI_STATE_TREE_GROUP_NONE;
+ return BROTLI_SUCCESS;
+}
+
+/* Decodes a context map.
+ Decoding is done in 4 phases:
+ 1) Read auxiliary information (6..16 bits) and allocate memory.
+ In case of trivial context map, decoding is finished at this phase.
+ 2) Decode Huffman table using ReadHuffmanCode function.
+ This table will be used for reading context map items.
+ 3) Read context map items; "0" values could be run-length encoded.
+ 4) Optionally, apply InverseMoveToFront transform to the resulting map.
+ */
+static BrotliErrorCode DecodeContextMap(uint32_t context_map_size,
+ uint32_t* num_htrees,
+ uint8_t** context_map_arg,
+ BrotliState* s) {
+ BrotliBitReader* br = &s->br;
+ BrotliErrorCode result = BROTLI_SUCCESS;
+
+ switch ((int)s->substate_context_map) {
+ case BROTLI_STATE_CONTEXT_MAP_NONE:
+ result = DecodeVarLenUint8(s, br, num_htrees);
+ if (result != BROTLI_SUCCESS) {
+ return result;
+ }
+ (*num_htrees)++;
+ s->context_index = 0;
+ BROTLI_LOG_UINT(context_map_size);
+ BROTLI_LOG_UINT(*num_htrees);
+ *context_map_arg = (uint8_t*)BROTLI_ALLOC(s, (size_t)context_map_size);
+ if (*context_map_arg == 0) {
+ return BROTLI_FAILURE(BROTLI_ERROR_ALLOC_CONTEXT_MAP);
+ }
+ if (*num_htrees <= 1) {
+ memset(*context_map_arg, 0, (size_t)context_map_size);
+ return BROTLI_SUCCESS;
+ }
+ s->substate_context_map = BROTLI_STATE_CONTEXT_MAP_READ_PREFIX;
+ /* No break, continue to next state. */
+ case BROTLI_STATE_CONTEXT_MAP_READ_PREFIX: {
+ uint32_t bits;
+ /* In next stage ReadHuffmanCode uses at least 4 bits, so it is safe
+ to peek 4 bits ahead. */
+ if (!BrotliSafeGetBits(br, 5, &bits)) {
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ if ((bits & 1) != 0) { /* Use RLE for zeroes. */
+ s->max_run_length_prefix = (bits >> 1) + 1;
+ BrotliDropBits(br, 5);
+ } else {
+ s->max_run_length_prefix = 0;
+ BrotliDropBits(br, 1);
+ }
+ BROTLI_LOG_UINT(s->max_run_length_prefix);
+ s->substate_context_map = BROTLI_STATE_CONTEXT_MAP_HUFFMAN;
+ /* No break, continue to next state. */
+ }
+ case BROTLI_STATE_CONTEXT_MAP_HUFFMAN:
+ result = ReadHuffmanCode(*num_htrees + s->max_run_length_prefix,
+ s->context_map_table, NULL, s);
+ if (result != BROTLI_SUCCESS) return result;
+ s->code = 0xFFFF;
+ s->substate_context_map = BROTLI_STATE_CONTEXT_MAP_DECODE;
+ /* No break, continue to next state. */
+ case BROTLI_STATE_CONTEXT_MAP_DECODE: {
+ uint32_t context_index = s->context_index;
+ uint32_t max_run_length_prefix = s->max_run_length_prefix;
+ uint8_t* context_map = *context_map_arg;
+ uint32_t code = s->code;
+ if (code != 0xFFFF) {
+ goto rleCode;
+ }
+ while (context_index < context_map_size) {
+ if (!SafeReadSymbol(s->context_map_table, br, &code)) {
+ s->code = 0xFFFF;
+ s->context_index = context_index;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ BROTLI_LOG_UINT(code);
+
+ if (code == 0) {
+ context_map[context_index++] = 0;
+ continue;
+ }
+ if (code > max_run_length_prefix) {
+ context_map[context_index++] =
+ (uint8_t)(code - max_run_length_prefix);
+ continue;
+ }
+rleCode:
+ {
+ uint32_t reps;
+ if (!BrotliSafeReadBits(br, code, &reps)) {
+ s->code = code;
+ s->context_index = context_index;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ reps += 1U << code;
+ BROTLI_LOG_UINT(reps);
+ if (context_index + reps > context_map_size) {
+ return BROTLI_FAILURE(BROTLI_ERROR_FORMAT_CONTEXT_MAP_REPEAT);
+ }
+ do {
+ context_map[context_index++] = 0;
+ } while (--reps);
+ }
+ }
+ /* No break, continue to next state. */
+ }
+ case BROTLI_STATE_CONTEXT_MAP_TRANSFORM: {
+ uint32_t bits;
+ if (!BrotliSafeReadBits(br, 1, &bits)) {
+ s->substate_context_map = BROTLI_STATE_CONTEXT_MAP_TRANSFORM;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ if (bits != 0) {
+ InverseMoveToFrontTransform(*context_map_arg, context_map_size, s);
+ }
+ s->substate_context_map = BROTLI_STATE_CONTEXT_MAP_NONE;
+ return BROTLI_SUCCESS;
+ }
+ default:
+ return BROTLI_FAILURE(BROTLI_ERROR_UNREACHABLE);
+ }
+}
+
+/* Decodes a command or literal and updates block type ringbuffer.
+ Reads 3..54 bits. */
+static BROTLI_INLINE int DecodeBlockTypeAndLength(int safe,
+ BrotliState* s, int tree_type) {
+ uint32_t max_block_type = s->num_block_types[tree_type];
+ const HuffmanCode* type_tree = &s->block_type_trees[
+ tree_type * BROTLI_HUFFMAN_MAX_SIZE_258];
+ const HuffmanCode* len_tree = &s->block_len_trees[
+ tree_type * BROTLI_HUFFMAN_MAX_SIZE_26];
+ BrotliBitReader* br = &s->br;
+ uint32_t* ringbuffer = &s->block_type_rb[tree_type * 2];
+ uint32_t block_type;
+
+ /* Read 0..15 + 3..39 bits */
+ if (!safe) {
+ block_type = ReadSymbol(type_tree, br);
+ s->block_length[tree_type] = ReadBlockLength(len_tree, br);
+ } else {
+ BrotliBitReaderState memento;
+ BrotliBitReaderSaveState(br, &memento);
+ if (!SafeReadSymbol(type_tree, br, &block_type)) return 0;
+ if (!SafeReadBlockLength(s, &s->block_length[tree_type], len_tree, br)) {
+ s->substate_read_block_length = BROTLI_STATE_READ_BLOCK_LENGTH_NONE;
+ BrotliBitReaderRestoreState(br, &memento);
+ return 0;
+ }
+ }
+
+ if (block_type == 1) {
+ block_type = ringbuffer[1] + 1;
+ } else if (block_type == 0) {
+ block_type = ringbuffer[0];
+ } else {
+ block_type -= 2;
+ }
+ if (block_type >= max_block_type) {
+ block_type -= max_block_type;
+ }
+ ringbuffer[0] = ringbuffer[1];
+ ringbuffer[1] = block_type;
+ return 1;
+}
+
+static BROTLI_INLINE void DetectTrivialLiteralBlockTypes(BrotliState* s) {
+ size_t i;
+ for (i = 0; i < 8; ++i) s->trivial_literal_contexts[i] = 0;
+ for (i = 0; i < s->num_block_types[0]; i++) {
+ size_t offset = i << kLiteralContextBits;
+ size_t error = 0;
+ size_t sample = s->context_map[offset];
+ size_t j;
+ for (j = 0; j < (1u << kLiteralContextBits);) {
+ BROTLI_REPEAT(4, error |= s->context_map[offset + j++] ^ sample;)
+ }
+ if (error == 0) {
+ s->trivial_literal_contexts[i >> 5] |= 1u << (i & 31);
+ }
+ }
+}
+
+static BROTLI_INLINE void PrepareLiteralDecoding(BrotliState* s) {
+ uint8_t context_mode;
+ size_t trivial;
+ uint32_t block_type = s->block_type_rb[1];
+ uint32_t context_offset = block_type << kLiteralContextBits;
+ s->context_map_slice = s->context_map + context_offset;
+ trivial = s->trivial_literal_contexts[block_type >> 5];
+ s->trivial_literal_context = (trivial >> (block_type & 31)) & 1;
+ s->literal_htree = s->literal_hgroup.htrees[s->context_map_slice[0]];
+ context_mode = s->context_modes[block_type];
+ s->context_lookup1 = &kContextLookup[kContextLookupOffsets[context_mode]];
+ s->context_lookup2 = &kContextLookup[kContextLookupOffsets[context_mode + 1]];
+}
+
+/* Decodes the block type and updates the state for literal context.
+ Reads 3..54 bits. */
+static BROTLI_INLINE int DecodeLiteralBlockSwitchInternal(int safe,
+ BrotliState* s) {
+ if (!DecodeBlockTypeAndLength(safe, s, 0)) {
+ return 0;
+ }
+ PrepareLiteralDecoding(s);
+ return 1;
+}
+
+static void BROTLI_NOINLINE DecodeLiteralBlockSwitch(BrotliState* s) {
+ DecodeLiteralBlockSwitchInternal(0, s);
+}
+
+static int BROTLI_NOINLINE SafeDecodeLiteralBlockSwitch(BrotliState* s) {
+ return DecodeLiteralBlockSwitchInternal(1, s);
+}
+
+/* Block switch for insert/copy length.
+ Reads 3..54 bits. */
+static BROTLI_INLINE int DecodeCommandBlockSwitchInternal(int safe,
+ BrotliState* s) {
+ if (!DecodeBlockTypeAndLength(safe, s, 1)) {
+ return 0;
+ }
+ s->htree_command = s->insert_copy_hgroup.htrees[s->block_type_rb[3]];
+ return 1;
+}
+
+static void BROTLI_NOINLINE DecodeCommandBlockSwitch(BrotliState* s) {
+ DecodeCommandBlockSwitchInternal(0, s);
+}
+static int BROTLI_NOINLINE SafeDecodeCommandBlockSwitch(BrotliState* s) {
+ return DecodeCommandBlockSwitchInternal(1, s);
+}
+
+/* Block switch for distance codes.
+ Reads 3..54 bits. */
+static BROTLI_INLINE int DecodeDistanceBlockSwitchInternal(int safe,
+ BrotliState* s) {
+ if (!DecodeBlockTypeAndLength(safe, s, 2)) {
+ return 0;
+ }
+ s->dist_context_map_slice =
+ s->dist_context_map + (s->block_type_rb[5] << kDistanceContextBits);
+ s->dist_htree_index = s->dist_context_map_slice[s->distance_context];
+ return 1;
+}
+
+static void BROTLI_NOINLINE DecodeDistanceBlockSwitch(BrotliState* s) {
+ DecodeDistanceBlockSwitchInternal(0, s);
+}
+
+static int BROTLI_NOINLINE SafeDecodeDistanceBlockSwitch(BrotliState* s) {
+ return DecodeDistanceBlockSwitchInternal(1, s);
+}
+
+static BrotliErrorCode BROTLI_NOINLINE WriteRingBuffer(size_t* available_out,
+ uint8_t** next_out, size_t* total_out, BrotliState* s) {
+ size_t pos = (s->pos > s->ringbuffer_size) ? (size_t)s->ringbuffer_size
+ : (size_t)(s->pos);
+ uint8_t* start =
+ s->ringbuffer + (s->partial_pos_out & (size_t)s->ringbuffer_mask);
+ size_t partial_pos_rb = (s->rb_roundtrips * (size_t)s->ringbuffer_size) + pos;
+ size_t to_write = (partial_pos_rb - s->partial_pos_out);
+ size_t num_written = *available_out;
+ if (num_written > to_write) {
+ num_written = to_write;
+ }
+ if (s->meta_block_remaining_len < 0) {
+ return BROTLI_FAILURE(BROTLI_ERROR_FORMAT_BLOCK_LENGTH_1);
+ }
+ memcpy(*next_out, start, num_written);
+ *next_out += num_written;
+ *available_out -= num_written;
+ BROTLI_LOG_UINT(to_write);
+ BROTLI_LOG_UINT(num_written);
+ s->partial_pos_out += num_written;
+ if (total_out) *total_out = s->partial_pos_out;
+ if (num_written < to_write) {
+ return BROTLI_NEEDS_MORE_OUTPUT;
+ }
+
+ if (s->pos >= s->ringbuffer_size) {
+ s->pos -= s->ringbuffer_size;
+ s->rb_roundtrips++;
+ }
+ return BROTLI_SUCCESS;
+}
+
+/* Allocates ringbuffer.
+
+ s->ringbuffer_size MUST be updated by BrotliCalculateRingBufferSize before
+ this function is called.
+
+ Last two bytes of ringbuffer are initialized to 0, so context calculation
+ could be done uniformly for the first two and all other positions.
+
+ Custom dictionary, if any, is copied to the end of ringbuffer.
+*/
+static int BROTLI_NOINLINE BrotliAllocateRingBuffer(BrotliState* s) {
+ /* We need the slack region for the following reasons:
+ - doing up to two 16-byte copies for fast backward copying
+ - inserting transformed dictionary word (5 prefix + 24 base + 8 suffix) */
+ static const int kRingBufferWriteAheadSlack = 42;
+ s->ringbuffer = (uint8_t*)BROTLI_ALLOC(s, (size_t)(s->ringbuffer_size +
+ kRingBufferWriteAheadSlack));
+ if (s->ringbuffer == 0) {
+ return 0;
+ }
+
+ s->ringbuffer_end = s->ringbuffer + s->ringbuffer_size;
+
+ s->ringbuffer[s->ringbuffer_size - 2] = 0;
+ s->ringbuffer[s->ringbuffer_size - 1] = 0;
+
+ if (s->custom_dict) {
+ memcpy(&s->ringbuffer[(-s->custom_dict_size) & s->ringbuffer_mask],
+ s->custom_dict, (size_t)s->custom_dict_size);
+ }
+
+ return 1;
+}
+
+static BrotliErrorCode BROTLI_NOINLINE CopyUncompressedBlockToOutput(
+ size_t* available_out, uint8_t** next_out, size_t* total_out,
+ BrotliState* s) {
+ /* TODO: avoid allocation for single uncompressed block. */
+ if (!s->ringbuffer && !BrotliAllocateRingBuffer(s)) {
+ return BROTLI_FAILURE(BROTLI_ERROR_ALLOC_RING_BUFFER_1);
+ }
+
+ /* State machine */
+ for (;;) {
+ switch (s->substate_uncompressed) {
+ case BROTLI_STATE_UNCOMPRESSED_NONE: {
+ int nbytes = (int)BrotliGetRemainingBytes(&s->br);
+ if (nbytes > s->meta_block_remaining_len) {
+ nbytes = s->meta_block_remaining_len;
+ }
+ if (s->pos + nbytes > s->ringbuffer_size) {
+ nbytes = s->ringbuffer_size - s->pos;
+ }
+ /* Copy remaining bytes from s->br.buf_ to ringbuffer. */
+ BrotliCopyBytes(&s->ringbuffer[s->pos], &s->br, (size_t)nbytes);
+ s->pos += nbytes;
+ s->meta_block_remaining_len -= nbytes;
+ if (s->pos < s->ringbuffer_size) {
+ if (s->meta_block_remaining_len == 0) {
+ return BROTLI_SUCCESS;
+ }
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ s->substate_uncompressed = BROTLI_STATE_UNCOMPRESSED_WRITE;
+ /* No break, continue to next state */
+ }
+ case BROTLI_STATE_UNCOMPRESSED_WRITE: {
+ BrotliErrorCode result =
+ WriteRingBuffer(available_out, next_out, total_out, s);
+ if (result != BROTLI_SUCCESS) {
+ return result;
+ }
+ s->max_distance = s->max_backward_distance;
+ s->substate_uncompressed = BROTLI_STATE_UNCOMPRESSED_NONE;
+ break;
+ }
+ }
+ }
+ BROTLI_DCHECK(0); /* Unreachable */
+}
+
+int BrotliDecompressedSize(size_t encoded_size,
+ const uint8_t* encoded_buffer,
+ size_t* decoded_size) {
+ BrotliState s;
+ int next_block_header;
+ BrotliStateInit(&s);
+ s.br.next_in = encoded_buffer;
+ s.br.avail_in = encoded_size;
+ if (!BrotliWarmupBitReader(&s.br)) {
+ return 0;
+ }
+ DecodeWindowBits(&s.br);
+ if (DecodeMetaBlockLength(&s, &s.br) != BROTLI_SUCCESS) {
+ return 0;
+ }
+ *decoded_size = (size_t)s.meta_block_remaining_len;
+ if (s.is_last_metablock) {
+ return 1;
+ }
+ if (!s.is_uncompressed || !BrotliJumpToByteBoundary(&s.br)) {
+ return 0;
+ }
+ next_block_header = BrotliPeekByte(&s.br, (size_t)s.meta_block_remaining_len);
+ return (next_block_header != -1) && ((next_block_header & 3) == 3);
+}
+
+/* Calculates the smallest feasible ring buffer.
+
+ If we know the data size is small, do not allocate more ringbuffer
+ size than needed to reduce memory usage.
+
+ When this method is called, metablock size and flags MUST be decoded.
+*/
+static void BROTLI_NOINLINE BrotliCalculateRingBufferSize(BrotliState* s,
+ BrotliBitReader* br) {
+ int is_last = s->is_last_metablock;
+ int window_size = 1 << s->window_bits;
+ s->ringbuffer_size = window_size;
+
+ if (s->is_uncompressed) {
+ int next_block_header =
+ BrotliPeekByte(br, (size_t)s->meta_block_remaining_len);
+ if (next_block_header != -1) { /* Peek succeeded */
+ if ((next_block_header & 3) == 3) { /* ISLAST and ISEMPTY */
+ is_last = 1;
+ }
+ }
+ }
+
+ /* We need at least 2 bytes of ring buffer size to get the last two
+ bytes for context from there */
+ if (is_last) {
+ int min_size_x2 = (s->meta_block_remaining_len + s->custom_dict_size) * 2;
+ while (s->ringbuffer_size >= min_size_x2 && s->ringbuffer_size > 32) {
+ s->ringbuffer_size >>= 1;
+ }
+ }
+
+ s->ringbuffer_mask = s->ringbuffer_size - 1;
+}
+
+/* Reads 1..256 2-bit context modes. */
+static BrotliErrorCode ReadContextModes(BrotliState* s) {
+ BrotliBitReader* br = &s->br;
+ int i = s->loop_counter;
+
+ while (i < (int)s->num_block_types[0]) {
+ uint32_t bits;
+ if (!BrotliSafeReadBits(br, 2, &bits)) {
+ s->loop_counter = i;
+ return BROTLI_NEEDS_MORE_INPUT;
+ }
+ s->context_modes[i] = (uint8_t)(bits << 1);
+ BROTLI_LOG_ARRAY_INDEX(s->context_modes, i);
+ i++;
+ }
+ return BROTLI_SUCCESS;
+}
+
+static BROTLI_INLINE void TakeDistanceFromRingBuffer(BrotliState* s) {
+ if (s->distance_code == 0) {
+ --s->dist_rb_idx;
+ s->distance_code = s->dist_rb[s->dist_rb_idx & 3];
+ } else {
+ int distance_code = s->distance_code << 1;
+ /* kDistanceShortCodeIndexOffset has 2-bit values from LSB: */
+ /* 3, 2, 1, 0, 3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2 */
+ const uint32_t kDistanceShortCodeIndexOffset = 0xaaafff1b;
+ /* kDistanceShortCodeValueOffset has 2-bit values from LSB: */
+ /*-0, 0,-0, 0,-1, 1,-2, 2,-3, 3,-1, 1,-2, 2,-3, 3 */
+ const uint32_t kDistanceShortCodeValueOffset = 0xfa5fa500;
+ int v = (s->dist_rb_idx +
+ (int)(kDistanceShortCodeIndexOffset >> distance_code)) & 0x3;
+ s->distance_code = s->dist_rb[v];
+ v = (int)(kDistanceShortCodeValueOffset >> distance_code) & 0x3;
+ if ((distance_code & 0x3) != 0) {
+ s->distance_code += v;
+ } else {
+ s->distance_code -= v;
+ if (s->distance_code <= 0) {
+ /* A huge distance will cause a BROTLI_FAILURE() soon. */
+ /* This is a little faster than failing here. */
+ s->distance_code = 0x0fffffff;
+ }
+ }
+ }
+}
+
+static BROTLI_INLINE int SafeReadBits(
+ BrotliBitReader* const br, uint32_t n_bits, uint32_t* val) {
+ if (n_bits != 0) {
+ return BrotliSafeReadBits(br, n_bits, val);
+ } else {
+ *val = 0;
+ return 1;
+ }
+}
+
+/* Precondition: s->distance_code < 0 */
+static BROTLI_INLINE int ReadDistanceInternal(int safe,
+ BrotliState* s, BrotliBitReader* br) {
+ int distval;
+ BrotliBitReaderState memento;
+ HuffmanCode* distance_tree = s->distance_hgroup.htrees[s->dist_htree_index];
+ if (!safe) {
+ s->distance_code = (int)ReadSymbol(distance_tree, br);
+ } else {
+ uint32_t code;
+ BrotliBitReaderSaveState(br, &memento);
+ if (!SafeReadSymbol(distance_tree, br, &code)) {
+ return 0;
+ }
+ s->distance_code = (int)code;
+ }
+ /* Convert the distance code to the actual distance by possibly */
+ /* looking up past distances from the s->ringbuffer. */
+ if ((s->distance_code & ~0xf) == 0) {
+ TakeDistanceFromRingBuffer(s);
+ --s->block_length[2];
+ return 1;
+ }
+ distval = s->distance_code - (int)s->num_direct_distance_codes;
+ if (distval >= 0) {
+ uint32_t nbits;
+ int postfix;
+ int offset;
+ if (!safe && (s->distance_postfix_bits == 0)) {
+ nbits = ((uint32_t)distval >> 1) + 1;
+ offset = ((2 + (distval & 1)) << nbits) - 4;
+ s->distance_code = (int)s->num_direct_distance_codes + offset +
+ (int)BrotliReadBits(br, nbits);
+ } else {
+ /* This branch also works well when s->distance_postfix_bits == 0 */
+ uint32_t bits;
+ postfix = distval & s->distance_postfix_mask;
+ distval >>= s->distance_postfix_bits;
+ nbits = ((uint32_t)distval >> 1) + 1;
+ if (safe) {
+ if (!SafeReadBits(br, nbits, &bits)) {
+ s->distance_code = -1; /* Restore precondition. */
+ BrotliBitReaderRestoreState(br, &memento);
+ return 0;
+ }
+ } else {
+ bits = BrotliReadBits(br, nbits);
+ }
+ offset = ((2 + (distval & 1)) << nbits) - 4;
+ s->distance_code = (int)s->num_direct_distance_codes +
+ ((offset + (int)bits) << s->distance_postfix_bits) + postfix;
+ }
+ }
+ s->distance_code = s->distance_code - NUM_DISTANCE_SHORT_CODES + 1;
+ --s->block_length[2];
+ return 1;
+}
+
+static BROTLI_INLINE void ReadDistance(BrotliState* s, BrotliBitReader* br) {
+ ReadDistanceInternal(0, s, br);
+}
+
+static BROTLI_INLINE int SafeReadDistance(BrotliState* s, BrotliBitReader* br) {
+ return ReadDistanceInternal(1, s, br);
+}
+
+static BROTLI_INLINE int ReadCommandInternal(int safe,
+ BrotliState* s, BrotliBitReader* br, int* insert_length) {
+ uint32_t cmd_code;
+ uint32_t insert_len_extra = 0;
+ uint32_t copy_length;
+ CmdLutElement v;
+ BrotliBitReaderState memento;
+ if (!safe) {
+ cmd_code = ReadSymbol(s->htree_command, br);
+ } else {
+ BrotliBitReaderSaveState(br, &memento);
+ if (!SafeReadSymbol(s->htree_command, br, &cmd_code)) {
+ return 0;
+ }
+ }
+ v = kCmdLut[cmd_code];
+ s->distance_code = v.distance_code;
+ s->distance_context = v.context;
+ s->dist_htree_index = s->dist_context_map_slice[s->distance_context];
+ *insert_length = v.insert_len_offset;
+ if (!safe) {
+ if (PREDICT_FALSE(v.insert_len_extra_bits != 0)) {
+ insert_len_extra = BrotliReadBits(br, v.insert_len_extra_bits);
+ }
+ copy_length = BrotliReadBits(br, v.copy_len_extra_bits);
+ } else {
+ if (!SafeReadBits(br, v.insert_len_extra_bits, &insert_len_extra) ||
+ !SafeReadBits(br, v.copy_len_extra_bits, &copy_length)) {
+ BrotliBitReaderRestoreState(br, &memento);
+ return 0;
+ }
+ }
+ s->copy_length = (int)copy_length + v.copy_len_offset;
+ --s->block_length[1];
+ *insert_length += (int)insert_len_extra;
+ return 1;
+}
+
+static BROTLI_INLINE void ReadCommand(BrotliState* s, BrotliBitReader* br,
+ int* insert_length) {
+ ReadCommandInternal(0, s, br, insert_length);
+}
+
+static BROTLI_INLINE int SafeReadCommand(BrotliState* s, BrotliBitReader* br,
+ int* insert_length) {
+ return ReadCommandInternal(1, s, br, insert_length);
+}
+
+static BROTLI_INLINE int CheckInputAmount(int safe,
+ BrotliBitReader* const br, size_t num) {
+ if (safe) {
+ return 1;
+ }
+ return BrotliCheckInputAmount(br, num);
+}
+
+#define BROTLI_SAFE(METHOD) \
+ { \
+ if (safe) { \
+ if (!Safe##METHOD) { \
+ result = BROTLI_NEEDS_MORE_INPUT; \
+ goto saveStateAndReturn; \
+ } \
+ } else { \
+ METHOD; \
+ } \
+ }
+
+static BROTLI_INLINE BrotliErrorCode ProcessCommandsInternal(int safe,
+ BrotliState* s) {
+ int pos = s->pos;
+ int i = s->loop_counter;
+ BrotliErrorCode result = BROTLI_SUCCESS;
+ BrotliBitReader* br = &s->br;
+
+ if (!CheckInputAmount(safe, br, 28)) {
+ result = BROTLI_NEEDS_MORE_INPUT;
+ goto saveStateAndReturn;
+ }
+ if (!safe) {
+ BROTLI_UNUSED(BrotliWarmupBitReader(br));
+ }
+
+ /* Jump into state machine. */
+ if (s->state == BROTLI_STATE_COMMAND_BEGIN) {
+ goto CommandBegin;
+ } else if (s->state == BROTLI_STATE_COMMAND_INNER) {
+ goto CommandInner;
+ } else if (s->state == BROTLI_STATE_COMMAND_POST_DECODE_LITERALS) {
+ goto CommandPostDecodeLiterals;
+ } else if (s->state == BROTLI_STATE_COMMAND_POST_WRAP_COPY) {
+ goto CommandPostWrapCopy;
+ } else {
+ return BROTLI_FAILURE(BROTLI_ERROR_UNREACHABLE);
+ }
+
+CommandBegin:
+ if (safe) {
+ s->state = BROTLI_STATE_COMMAND_BEGIN;
+ }
+ if (!CheckInputAmount(safe, br, 28)) { /* 156 bits + 7 bytes */
+ s->state = BROTLI_STATE_COMMAND_BEGIN;
+ result = BROTLI_NEEDS_MORE_INPUT;
+ goto saveStateAndReturn;
+ }
+ if (PREDICT_FALSE(s->block_length[1] == 0)) {
+ BROTLI_SAFE(DecodeCommandBlockSwitch(s));
+ goto CommandBegin;
+ }
+ /* Read the insert/copy length in the command */
+ BROTLI_SAFE(ReadCommand(s, br, &i));
+ BROTLI_LOG(("[ProcessCommandsInternal] pos = %d insert = %d copy = %d\n",
+ pos, i, s->copy_length));
+ if (i == 0) {
+ goto CommandPostDecodeLiterals;
+ }
+ s->meta_block_remaining_len -= i;
+
+CommandInner:
+ if (safe) {
+ s->state = BROTLI_STATE_COMMAND_INNER;
+ }
+ /* Read the literals in the command */
+ if (s->trivial_literal_context) {
+ uint32_t bits;
+ uint32_t value;
+ PreloadSymbol(safe, s->literal_htree, br, &bits, &value);
+ do {
+ if (!CheckInputAmount(safe, br, 28)) { /* 162 bits + 7 bytes */
+ s->state = BROTLI_STATE_COMMAND_INNER;
+ result = BROTLI_NEEDS_MORE_INPUT;
+ goto saveStateAndReturn;
+ }
+ if (PREDICT_FALSE(s->block_length[0] == 0)) {
+ BROTLI_SAFE(DecodeLiteralBlockSwitch(s));
+ PreloadSymbol(safe, s->literal_htree, br, &bits, &value);
+ if (!s->trivial_literal_context) goto CommandInner;
+ }
+ if (!safe) {
+ s->ringbuffer[pos] =
+ (uint8_t)ReadPreloadedSymbol(s->literal_htree, br, &bits, &value);
+ } else {
+ uint32_t literal;
+ if (!SafeReadSymbol(s->literal_htree, br, &literal)) {
+ result = BROTLI_NEEDS_MORE_INPUT;
+ goto saveStateAndReturn;
+ }
+ s->ringbuffer[pos] = (uint8_t)literal;
+ }
+ --s->block_length[0];
+ BROTLI_LOG_ARRAY_INDEX(s->ringbuffer, pos);
+ ++pos;
+ if (PREDICT_FALSE(pos == s->ringbuffer_size)) {
+ s->state = BROTLI_STATE_COMMAND_INNER_WRITE;
+ --i;
+ goto saveStateAndReturn;
+ }
+ } while (--i != 0);
+ } else {
+ uint8_t p1 = s->ringbuffer[(pos - 1) & s->ringbuffer_mask];
+ uint8_t p2 = s->ringbuffer[(pos - 2) & s->ringbuffer_mask];
+ do {
+ const HuffmanCode* hc;
+ uint8_t context;
+ if (!CheckInputAmount(safe, br, 28)) { /* 162 bits + 7 bytes */
+ s->state = BROTLI_STATE_COMMAND_INNER;
+ result = BROTLI_NEEDS_MORE_INPUT;
+ goto saveStateAndReturn;
+ }
+ if (PREDICT_FALSE(s->block_length[0] == 0)) {
+ BROTLI_SAFE(DecodeLiteralBlockSwitch(s));
+ if (s->trivial_literal_context) goto CommandInner;
+ }
+ context = s->context_lookup1[p1] | s->context_lookup2[p2];
+ BROTLI_LOG_UINT(context);
+ hc = s->literal_hgroup.htrees[s->context_map_slice[context]];
+ p2 = p1;
+ if (!safe) {
+ p1 = (uint8_t)ReadSymbol(hc, br);
+ } else {
+ uint32_t literal;
+ if (!SafeReadSymbol(hc, br, &literal)) {
+ result = BROTLI_NEEDS_MORE_INPUT;
+ goto saveStateAndReturn;
+ }
+ p1 = (uint8_t)literal;
+ }
+ s->ringbuffer[pos] = p1;
+ --s->block_length[0];
+ BROTLI_LOG_UINT(s->context_map_slice[context]);
+ BROTLI_LOG_ARRAY_INDEX(s->ringbuffer, pos & s->ringbuffer_mask);
+ ++pos;
+ if (PREDICT_FALSE(pos == s->ringbuffer_size)) {
+ s->state = BROTLI_STATE_COMMAND_INNER_WRITE;
+ --i;
+ goto saveStateAndReturn;
+ }
+ } while (--i != 0);
+ }
+ BROTLI_LOG_UINT(s->meta_block_remaining_len);
+ if (PREDICT_FALSE(s->meta_block_remaining_len <= 0)) {
+ s->state = BROTLI_STATE_METABLOCK_DONE;
+ goto saveStateAndReturn;
+ }
+
+CommandPostDecodeLiterals:
+ if (safe) {
+ s->state = BROTLI_STATE_COMMAND_POST_DECODE_LITERALS;
+ }
+ if (s->distance_code >= 0) {
+ --s->dist_rb_idx;
+ s->distance_code = s->dist_rb[s->dist_rb_idx & 3];
+ goto postReadDistance; /* We already have the implicit distance */
+ }
+ /* Read distance code in the command, unless it was implicitly zero. */
+ if (PREDICT_FALSE(s->block_length[2] == 0)) {
+ BROTLI_SAFE(DecodeDistanceBlockSwitch(s));
+ }
+ BROTLI_SAFE(ReadDistance(s, br));
+postReadDistance:
+ BROTLI_LOG(("[ProcessCommandsInternal] pos = %d distance = %d\n",
+ pos, s->distance_code));
+ if (s->max_distance != s->max_backward_distance) {
+ if (pos < s->max_backward_distance_minus_custom_dict_size) {
+ s->max_distance = pos + s->custom_dict_size;
+ } else {
+ s->max_distance = s->max_backward_distance;
+ }
+ }
+ i = s->copy_length;
+ /* Apply copy of LZ77 back-reference, or static dictionary reference if
+ the distance is larger than the max LZ77 distance */
+ if (s->distance_code > s->max_distance) {
+ if (i >= kBrotliMinDictionaryWordLength &&
+ i <= kBrotliMaxDictionaryWordLength) {
+ int offset = (int)kBrotliDictionaryOffsetsByLength[i];
+ int word_id = s->distance_code - s->max_distance - 1;
+ uint32_t shift = kBrotliDictionarySizeBitsByLength[i];
+ int mask = (int)BitMask(shift);
+ int word_idx = word_id & mask;
+ int transform_idx = word_id >> shift;
+ offset += word_idx * i;
+ if (transform_idx < kNumTransforms) {
+ const uint8_t* word = &kBrotliDictionary[offset];
+ int len = i;
+ if (transform_idx == 0) {
+ memcpy(&s->ringbuffer[pos], word, (size_t)len);
+ } else {
+ len = TransformDictionaryWord(
+ &s->ringbuffer[pos], word, len, transform_idx);
+ }
+ pos += len;
+ s->meta_block_remaining_len -= len;
+ if (pos >= s->ringbuffer_size) {
+ /*s->partial_pos_rb += (size_t)s->ringbuffer_size;*/
+ s->state = BROTLI_STATE_COMMAND_POST_WRITE_1;
+ goto saveStateAndReturn;
+ }
+ } else {
+ BROTLI_LOG(("Invalid backward reference. pos: %d distance: %d "
+ "len: %d bytes left: %d\n",
+ pos, s->distance_code, i, s->meta_block_remaining_len));
+ return BROTLI_FAILURE(BROTLI_ERROR_FORMAT_TRANSFORM);
+ }
+ } else {
+ BROTLI_LOG(("Invalid backward reference. pos: %d distance: %d "
+ "len: %d bytes left: %d\n",
+ pos, s->distance_code, i, s->meta_block_remaining_len));
+ return BROTLI_FAILURE(BROTLI_ERROR_FORMAT_DICTIONARY);
+ }
+ } else {
+ int src_start = (pos - s->distance_code) & s->ringbuffer_mask;
+ uint8_t* copy_dst = &s->ringbuffer[pos];
+ uint8_t* copy_src = &s->ringbuffer[src_start];
+ int dst_end = pos + i;
+ int src_end = src_start + i;
+ /* update the recent distances cache */
+ s->dist_rb[s->dist_rb_idx & 3] = s->distance_code;
+ ++s->dist_rb_idx;
+ s->meta_block_remaining_len -= i;
+ /* There are 32+ bytes of slack in the ringbuffer allocation.
+ Also, we have 16 short codes, that make these 16 bytes irrelevant
+ in the ringbuffer. Let's copy over them as a first guess.
+ */
+ memmove16(copy_dst, copy_src);
+ if (src_end > pos && dst_end > src_start) {
+ /* Regions intersect. */
+ goto CommandPostWrapCopy;
+ }
+ if (dst_end >= s->ringbuffer_size || src_end >= s->ringbuffer_size) {
+ /* At least one region wraps. */
+ goto CommandPostWrapCopy;
+ }
+ pos += i;
+ if (i > 16) {
+ if (i > 32) {
+ memcpy(copy_dst + 16, copy_src + 16, (size_t)(i - 16));
+ } else {
+ /* This branch covers about 45% cases.
+ Fixed size short copy allows more compiler optimizations. */
+ memmove16(copy_dst + 16, copy_src + 16);
+ }
+ }
+ }
+ BROTLI_LOG_UINT(s->meta_block_remaining_len);
+ if (s->meta_block_remaining_len <= 0) {
+ /* Next metablock, if any */
+ s->state = BROTLI_STATE_METABLOCK_DONE;
+ goto saveStateAndReturn;
+ } else {
+ goto CommandBegin;
+ }
+CommandPostWrapCopy:
+ {
+ int wrap_guard = s->ringbuffer_size - pos;
+ while (--i >= 0) {
+ s->ringbuffer[pos] =
+ s->ringbuffer[(pos - s->distance_code) & s->ringbuffer_mask];
+ ++pos;
+ if (PREDICT_FALSE(--wrap_guard == 0)) {
+ s->state = BROTLI_STATE_COMMAND_POST_WRITE_2;
+ goto saveStateAndReturn;
+ }
+ }
+ }
+ if (s->meta_block_remaining_len <= 0) {
+ /* Next metablock, if any */
+ s->state = BROTLI_STATE_METABLOCK_DONE;
+ goto saveStateAndReturn;
+ } else {
+ goto CommandBegin;
+ }
+
+saveStateAndReturn:
+ s->pos = pos;
+ s->loop_counter = i;
+ return result;
+}
+
+#undef BROTLI_SAFE
+
+static BROTLI_NOINLINE BrotliErrorCode ProcessCommands(BrotliState* s) {
+ return ProcessCommandsInternal(0, s);
+}
+
+static BROTLI_NOINLINE BrotliErrorCode SafeProcessCommands(BrotliState* s) {
+ return ProcessCommandsInternal(1, s);
+}
+
+BrotliResult BrotliDecompressBuffer(size_t encoded_size,
+ const uint8_t* encoded_buffer,
+ size_t* decoded_size,
+ uint8_t* decoded_buffer) {
+ BrotliState s;
+ BrotliResult result;
+ size_t total_out = 0;
+ size_t available_in = encoded_size;
+ const uint8_t* next_in = encoded_buffer;
+ size_t available_out = *decoded_size;
+ uint8_t* next_out = decoded_buffer;
+ BrotliStateInit(&s);
+ result = BrotliDecompressStream(&available_in, &next_in, &available_out,
+ &next_out, &total_out, &s);
+ *decoded_size = total_out;
+ BrotliStateCleanup(&s);
+ if (result != BROTLI_RESULT_SUCCESS) {
+ result = BROTLI_RESULT_ERROR;
+ }
+ return result;
+}
+
+/* Invariant: input stream is never overconsumed:
+ * invalid input implies that the whole stream is invalid -> any amount of
+ input could be read and discarded
+ * when result is "needs more input", then at leat one more byte is REQUIRED
+ to complete decoding; all input data MUST be consumed by decoder, so
+ client could swap the input buffer
+ * when result is "needs more output" decoder MUST ensure that it doesn't
+ hold more than 7 bits in bit reader; this saves client from swapping input
+ buffer ahead of time
+ * when result is "success" decoder MUST return all unused data back to input
+ buffer; this is possible because the invariant is hold on enter
+*/
+BrotliResult BrotliDecompressStream(size_t* available_in,
+ const uint8_t** next_in, size_t* available_out, uint8_t** next_out,
+ size_t* total_out, BrotliState* s) {
+ BrotliErrorCode result = BROTLI_SUCCESS;
+ BrotliBitReader* br = &s->br;
+ if (s->buffer_length == 0) { /* Just connect bit reader to input stream. */
+ br->avail_in = *available_in;
+ br->next_in = *next_in;
+ } else {
+ /* At least one byte of input is required. More than one byte of input may
+ be required to complete the transaction -> reading more data must be
+ done in a loop -> do it in a main loop. */
+ result = BROTLI_NEEDS_MORE_INPUT;
+ br->next_in = &s->buffer.u8[0];
+ }
+ /* State machine */
+ for (;;) {
+ if (result != BROTLI_SUCCESS) { /* Error | needs more input/output */
+ if (result == BROTLI_NEEDS_MORE_INPUT) {
+ if (s->ringbuffer != 0) { /* Proactively push output. */
+ WriteRingBuffer(available_out, next_out, total_out, s);
+ }
+ if (s->buffer_length != 0) { /* Used with internal buffer. */
+ if (br->avail_in == 0) { /* Successfully finished read transaction. */
+ /* Accamulator contains less than 8 bits, because internal buffer
+ is expanded byte-by-byte until it is enough to complete read. */
+ s->buffer_length = 0;
+ /* Switch to input stream and restart. */
+ result = BROTLI_SUCCESS;
+ br->avail_in = *available_in;
+ br->next_in = *next_in;
+ continue;
+ } else if (*available_in != 0) {
+ /* Not enough data in buffer, but can take one more byte from
+ input stream. */
+ result = BROTLI_SUCCESS;
+ s->buffer.u8[s->buffer_length] = **next_in;
+ s->buffer_length++;
+ br->avail_in = s->buffer_length;
+ (*next_in)++;
+ (*available_in)--;
+ /* Retry with more data in buffer. */
+ continue;
+ }
+ /* Can't finish reading and no more input.*/
+ break;
+ } else { /* Input stream doesn't contain enough input. */
+ /* Copy tail to internal buffer and return. */
+ *next_in = br->next_in;
+ *available_in = br->avail_in;
+ while (*available_in) {
+ s->buffer.u8[s->buffer_length] = **next_in;
+ s->buffer_length++;
+ (*next_in)++;
+ (*available_in)--;
+ }
+ break;
+ }
+ /* Unreachable. */
+ }
+
+ /* Fail or needs more output. */
+
+ if (s->buffer_length != 0) {
+ /* Just consumed the buffered input and produced some output. Otherwise
+ it would result in "needs more input". Reset internal buffer.*/
+ s->buffer_length = 0;
+ } else {
+ /* Using input stream in last iteration. When decoder switches to input
+ stream it has less than 8 bits in accamulator, so it is safe to
+ return unused accamulator bits there. */
+ BrotliBitReaderUnload(br);
+ *available_in = br->avail_in;
+ *next_in = br->next_in;
+ }
+ break;
+ }
+ switch (s->state) {
+ case BROTLI_STATE_UNINITED:
+ /* Prepare to the first read. */
+ if (!BrotliWarmupBitReader(br)) {
+ result = BROTLI_NEEDS_MORE_INPUT;
+ break;
+ }
+ /* Decode window size. */
+ s->window_bits = DecodeWindowBits(br); /* Reads 1..7 bits. */
+ BROTLI_LOG_UINT(s->window_bits);
+ if (s->window_bits == 9) {
+ /* Value 9 is reserved for future use. */
+ result = BROTLI_FAILURE(BROTLI_ERROR_FORMAT_WINDOW_BITS);
+ break;
+ }
+ /* Maximum distance, see section 9.1. of the spec. */
+ s->max_backward_distance = (1 << s->window_bits) - 16;
+ /* Limit custom dictionary size. */
+ if (s->custom_dict_size >= s->max_backward_distance) {
+ s->custom_dict += s->custom_dict_size - s->max_backward_distance;
+ s->custom_dict_size = s->max_backward_distance;
+ }
+ s->max_backward_distance_minus_custom_dict_size =
+ s->max_backward_distance - s->custom_dict_size;
+
+ /* Allocate memory for both block_type_trees and block_len_trees. */
+ s->block_type_trees = (HuffmanCode*)BROTLI_ALLOC(s,
+ sizeof(HuffmanCode) * 3 *
+ (BROTLI_HUFFMAN_MAX_SIZE_258 + BROTLI_HUFFMAN_MAX_SIZE_26));
+ if (s->block_type_trees == 0) {
+ result = BROTLI_FAILURE(BROTLI_ERROR_ALLOC_BLOCK_TYPE_TREES);
+ break;
+ }
+ s->block_len_trees =
+ s->block_type_trees + 3 * BROTLI_HUFFMAN_MAX_SIZE_258;
+
+ s->state = BROTLI_STATE_METABLOCK_BEGIN;
+ /* No break, continue to next state */
+ case BROTLI_STATE_METABLOCK_BEGIN:
+ BrotliStateMetablockBegin(s);
+ BROTLI_LOG_UINT(s->pos);
+ s->state = BROTLI_STATE_METABLOCK_HEADER;
+ /* No break, continue to next state */
+ case BROTLI_STATE_METABLOCK_HEADER:
+ result = DecodeMetaBlockLength(s, br); /* Reads 2 - 31 bits. */
+ if (result != BROTLI_SUCCESS) {
+ break;
+ }
+ BROTLI_LOG_UINT(s->is_last_metablock);
+ BROTLI_LOG_UINT(s->meta_block_remaining_len);
+ BROTLI_LOG_UINT(s->is_metadata);
+ BROTLI_LOG_UINT(s->is_uncompressed);
+ if (s->is_metadata || s->is_uncompressed) {
+ if (!BrotliJumpToByteBoundary(br)) {
+ result = BROTLI_FAILURE(BROTLI_ERROR_FORMAT_PADDING_1);
+ break;
+ }
+ }
+ if (s->is_metadata) {
+ s->state = BROTLI_STATE_METADATA;
+ break;
+ }
+ if (s->meta_block_remaining_len == 0) {
+ s->state = BROTLI_STATE_METABLOCK_DONE;
+ break;
+ }
+ if (!s->ringbuffer) {
+ BrotliCalculateRingBufferSize(s, br);
+ }
+ if (s->is_uncompressed) {
+ s->state = BROTLI_STATE_UNCOMPRESSED;
+ break;
+ }
+ s->loop_counter = 0;
+ s->state = BROTLI_STATE_HUFFMAN_CODE_0;
+ break;
+ case BROTLI_STATE_UNCOMPRESSED: {
+ int bytes_copied = s->meta_block_remaining_len;
+ result = CopyUncompressedBlockToOutput(
+ available_out, next_out, total_out, s);
+ bytes_copied -= s->meta_block_remaining_len;
+ if (result != BROTLI_SUCCESS) {
+ break;
+ }
+ s->state = BROTLI_STATE_METABLOCK_DONE;
+ break;
+ }
+ case BROTLI_STATE_METADATA:
+ for (; s->meta_block_remaining_len > 0; --s->meta_block_remaining_len) {
+ uint32_t bits;
+ /* Read one byte and ignore it. */
+ if (!BrotliSafeReadBits(br, 8, &bits)) {
+ result = BROTLI_NEEDS_MORE_INPUT;
+ break;
+ }
+ }
+ if (result == BROTLI_SUCCESS) {
+ s->state = BROTLI_STATE_METABLOCK_DONE;
+ }
+ break;
+ case BROTLI_STATE_HUFFMAN_CODE_0:
+ if (s->loop_counter >= 3) {
+ s->state = BROTLI_STATE_METABLOCK_HEADER_2;
+ break;
+ }
+ /* Reads 1..11 bits. */
+ result = DecodeVarLenUint8(s, br, &s->num_block_types[s->loop_counter]);
+ if (result != BROTLI_SUCCESS) {
+ break;
+ }
+ s->num_block_types[s->loop_counter]++;
+ BROTLI_LOG_UINT(s->num_block_types[s->loop_counter]);
+ if (s->num_block_types[s->loop_counter] < 2) {
+ s->loop_counter++;
+ break;
+ }
+ s->state = BROTLI_STATE_HUFFMAN_CODE_1;
+ /* No break, continue to next state */
+ case BROTLI_STATE_HUFFMAN_CODE_1: {
+ int tree_offset = s->loop_counter * BROTLI_HUFFMAN_MAX_SIZE_258;
+ result = ReadHuffmanCode(s->num_block_types[s->loop_counter] + 2,
+ &s->block_type_trees[tree_offset], NULL, s);
+ if (result != BROTLI_SUCCESS) break;
+ s->state = BROTLI_STATE_HUFFMAN_CODE_2;
+ /* No break, continue to next state */
+ }
+ case BROTLI_STATE_HUFFMAN_CODE_2: {
+ int tree_offset = s->loop_counter * BROTLI_HUFFMAN_MAX_SIZE_26;
+ result = ReadHuffmanCode(kNumBlockLengthCodes,
+ &s->block_len_trees[tree_offset], NULL, s);
+ if (result != BROTLI_SUCCESS) break;
+ s->state = BROTLI_STATE_HUFFMAN_CODE_3;
+ /* No break, continue to next state */
+ }
+ case BROTLI_STATE_HUFFMAN_CODE_3: {
+ int tree_offset = s->loop_counter * BROTLI_HUFFMAN_MAX_SIZE_26;
+ if (!SafeReadBlockLength(s, &s->block_length[s->loop_counter],
+ &s->block_len_trees[tree_offset], br)) {
+ result = BROTLI_NEEDS_MORE_INPUT;
+ break;
+ }
+ BROTLI_LOG_UINT(s->block_length[s->loop_counter]);
+ s->loop_counter++;
+ s->state = BROTLI_STATE_HUFFMAN_CODE_0;
+ break;
+ }
+ case BROTLI_STATE_METABLOCK_HEADER_2: {
+ uint32_t bits;
+ if (!BrotliSafeReadBits(br, 6, &bits)) {
+ result = BROTLI_NEEDS_MORE_INPUT;
+ break;
+ }
+ s->distance_postfix_bits = bits & BitMask(2);
+ bits >>= 2;
+ s->num_direct_distance_codes =
+ NUM_DISTANCE_SHORT_CODES + (bits << s->distance_postfix_bits);
+ BROTLI_LOG_UINT(s->num_direct_distance_codes);
+ BROTLI_LOG_UINT(s->distance_postfix_bits);
+ s->distance_postfix_mask = (int)BitMask(s->distance_postfix_bits);
+ s->context_modes =
+ (uint8_t*)BROTLI_ALLOC(s, (size_t)s->num_block_types[0]);
+ if (s->context_modes == 0) {
+ result = BROTLI_FAILURE(BROTLI_ERROR_ALLOC_CONTEXT_MODES);
+ break;
+ }
+ s->loop_counter = 0;
+ s->state = BROTLI_STATE_CONTEXT_MODES;
+ /* No break, continue to next state */
+ }
+ case BROTLI_STATE_CONTEXT_MODES:
+ result = ReadContextModes(s);
+ if (result != BROTLI_SUCCESS) {
+ break;
+ }
+ s->state = BROTLI_STATE_CONTEXT_MAP_1;
+ /* No break, continue to next state */
+ case BROTLI_STATE_CONTEXT_MAP_1:
+ result = DecodeContextMap(
+ s->num_block_types[0] << kLiteralContextBits,
+ &s->num_literal_htrees, &s->context_map, s);
+ if (result != BROTLI_SUCCESS) {
+ break;
+ }
+ DetectTrivialLiteralBlockTypes(s);
+ s->state = BROTLI_STATE_CONTEXT_MAP_2;
+ /* No break, continue to next state */
+ case BROTLI_STATE_CONTEXT_MAP_2:
+ {
+ uint32_t num_distance_codes =
+ s->num_direct_distance_codes + (48U << s->distance_postfix_bits);
+ result = DecodeContextMap(
+ s->num_block_types[2] << kDistanceContextBits,
+ &s->num_dist_htrees, &s->dist_context_map, s);
+ if (result != BROTLI_SUCCESS) {
+ break;
+ }
+ BrotliHuffmanTreeGroupInit(s, &s->literal_hgroup, kNumLiteralCodes,
+ s->num_literal_htrees);
+ BrotliHuffmanTreeGroupInit(s, &s->insert_copy_hgroup,
+ kNumInsertAndCopyCodes,
+ s->num_block_types[1]);
+ BrotliHuffmanTreeGroupInit(s, &s->distance_hgroup, num_distance_codes,
+ s->num_dist_htrees);
+ if (s->literal_hgroup.codes == 0 ||
+ s->insert_copy_hgroup.codes == 0 ||
+ s->distance_hgroup.codes == 0) {
+ return SaveErrorCode(s,
+ BROTLI_FAILURE(BROTLI_ERROR_ALLOC_TREE_GROUPS));
+ }
+ }
+ s->loop_counter = 0;
+ s->state = BROTLI_STATE_TREE_GROUP;
+ /* No break, continue to next state */
+ case BROTLI_STATE_TREE_GROUP:
+ {
+ HuffmanTreeGroup* hgroup = NULL;
+ switch (s->loop_counter) {
+ case 0:
+ hgroup = &s->literal_hgroup;
+ break;
+ case 1:
+ hgroup = &s->insert_copy_hgroup;
+ break;
+ case 2:
+ hgroup = &s->distance_hgroup;
+ break;
+ default:
+ return SaveErrorCode(s,
+ BROTLI_FAILURE(BROTLI_ERROR_UNREACHABLE));
+ }
+ result = HuffmanTreeGroupDecode(hgroup, s);
+ }
+ if (result != BROTLI_SUCCESS) break;
+ s->loop_counter++;
+ if (s->loop_counter >= 3) {
+ PrepareLiteralDecoding(s);
+ s->dist_context_map_slice = s->dist_context_map;
+ s->htree_command = s->insert_copy_hgroup.htrees[0];
+ if (!s->ringbuffer && !BrotliAllocateRingBuffer(s)) {
+ result = BROTLI_FAILURE(BROTLI_ERROR_ALLOC_RING_BUFFER_2);
+ break;
+ }
+ s->state = BROTLI_STATE_COMMAND_BEGIN;
+ }
+ break;
+ case BROTLI_STATE_COMMAND_BEGIN:
+ case BROTLI_STATE_COMMAND_INNER:
+ case BROTLI_STATE_COMMAND_POST_DECODE_LITERALS:
+ case BROTLI_STATE_COMMAND_POST_WRAP_COPY:
+ result = ProcessCommands(s);
+ if (result == BROTLI_NEEDS_MORE_INPUT) {
+ result = SafeProcessCommands(s);
+ }
+ break;
+ case BROTLI_STATE_COMMAND_INNER_WRITE:
+ case BROTLI_STATE_COMMAND_POST_WRITE_1:
+ case BROTLI_STATE_COMMAND_POST_WRITE_2:
+ result = WriteRingBuffer(available_out, next_out, total_out, s);
+ if (result != BROTLI_SUCCESS) {
+ break;
+ }
+ s->max_distance = s->max_backward_distance;
+ if (s->state == BROTLI_STATE_COMMAND_POST_WRITE_1) {
+ memcpy(s->ringbuffer, s->ringbuffer_end, (size_t)s->pos);
+ if (s->meta_block_remaining_len == 0) {
+ /* Next metablock, if any */
+ s->state = BROTLI_STATE_METABLOCK_DONE;
+ } else {
+ s->state = BROTLI_STATE_COMMAND_BEGIN;
+ }
+ break;
+ } else if (s->state == BROTLI_STATE_COMMAND_POST_WRITE_2) {
+ s->state = BROTLI_STATE_COMMAND_POST_WRAP_COPY;
+ } else { /* BROTLI_STATE_COMMAND_INNER_WRITE */
+ if (s->loop_counter == 0) {
+ if (s->meta_block_remaining_len == 0) {
+ s->state = BROTLI_STATE_METABLOCK_DONE;
+ } else {
+ s->state = BROTLI_STATE_COMMAND_POST_DECODE_LITERALS;
+ }
+ break;
+ }
+ s->state = BROTLI_STATE_COMMAND_INNER;
+ }
+ break;
+ case BROTLI_STATE_METABLOCK_DONE:
+ if (s->meta_block_remaining_len < 0) {
+ result = BROTLI_FAILURE(BROTLI_ERROR_FORMAT_BLOCK_LENGTH_2);
+ break;
+ }
+ BrotliStateCleanupAfterMetablock(s);
+ if (!s->is_last_metablock) {
+ s->state = BROTLI_STATE_METABLOCK_BEGIN;
+ break;
+ }
+ if (!BrotliJumpToByteBoundary(br)) {
+ result = BROTLI_FAILURE(BROTLI_ERROR_FORMAT_PADDING_2);
+ break;
+ }
+ if (s->buffer_length == 0) {
+ BrotliBitReaderUnload(br);
+ *available_in = br->avail_in;
+ *next_in = br->next_in;
+ }
+ s->state = BROTLI_STATE_DONE;
+ /* No break, continue to next state */
+ case BROTLI_STATE_DONE:
+ if (s->ringbuffer != 0) {
+ result = WriteRingBuffer(available_out, next_out, total_out, s);
+ if (result != BROTLI_SUCCESS) {
+ break;
+ }
+ }
+ return SaveErrorCode(s, result);
+ }
+ }
+ return SaveErrorCode(s, result);
+}
+
+void BrotliSetCustomDictionary(
+ size_t size, const uint8_t* dict, BrotliState* s) {
+ if (size > (1u << 24)) {
+ return;
+ }
+ s->custom_dict = dict;
+ s->custom_dict_size = (int)size;
+}
+
+BrotliErrorCode BrotliGetErrorCode(const BrotliState* s) {
+ return (BrotliErrorCode)s->error_code;
+}
+
+const char* BrotliErrorString(BrotliErrorCode c) {
+ switch (c) {
+#define _BROTLI_ERROR_CODE_CASE(PREFIX, NAME, CODE) \
+ case BROTLI ## PREFIX ## NAME: return #NAME;
+#define _BROTLI_NOTHING
+ BROTLI_ERROR_CODES_LIST(_BROTLI_ERROR_CODE_CASE, _BROTLI_NOTHING)
+#undef _BROTLI_ERROR_CODE_CASE
+#undef _BROTLI_NOTHING
+ default: return "INVALID";
+ }
+}
+
+#if defined(__cplusplus) || defined(c_plusplus)
+} /* extern "C" */
+#endif