summaryrefslogtreecommitdiffstats
path: root/media/libwebp/utils/bit_reader_utils.c
diff options
context:
space:
mode:
Diffstat (limited to 'media/libwebp/utils/bit_reader_utils.c')
-rw-r--r--media/libwebp/utils/bit_reader_utils.c222
1 files changed, 222 insertions, 0 deletions
diff --git a/media/libwebp/utils/bit_reader_utils.c b/media/libwebp/utils/bit_reader_utils.c
new file mode 100644
index 000000000..c3157e8fe
--- /dev/null
+++ b/media/libwebp/utils/bit_reader_utils.c
@@ -0,0 +1,222 @@
+// Copyright 2010 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Boolean decoder non-inlined methods
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#ifdef HAVE_CONFIG_H
+#include "../webp/config.h"
+#endif
+
+#include "./bit_reader_inl_utils.h"
+#include "../utils/utils.h"
+
+//------------------------------------------------------------------------------
+// VP8BitReader
+
+void VP8BitReaderSetBuffer(VP8BitReader* const br,
+ const uint8_t* const start,
+ size_t size) {
+ br->buf_ = start;
+ br->buf_end_ = start + size;
+ br->buf_max_ =
+ (size >= sizeof(lbit_t)) ? start + size - sizeof(lbit_t) + 1
+ : start;
+}
+
+void VP8InitBitReader(VP8BitReader* const br,
+ const uint8_t* const start, size_t size) {
+ assert(br != NULL);
+ assert(start != NULL);
+ assert(size < (1u << 31)); // limit ensured by format and upstream checks
+ br->range_ = 255 - 1;
+ br->value_ = 0;
+ br->bits_ = -8; // to load the very first 8bits
+ br->eof_ = 0;
+ VP8BitReaderSetBuffer(br, start, size);
+ VP8LoadNewBytes(br);
+}
+
+void VP8RemapBitReader(VP8BitReader* const br, ptrdiff_t offset) {
+ if (br->buf_ != NULL) {
+ br->buf_ += offset;
+ br->buf_end_ += offset;
+ br->buf_max_ += offset;
+ }
+}
+
+const uint8_t kVP8Log2Range[128] = {
+ 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
+ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+ 0
+};
+
+// range = ((range - 1) << kVP8Log2Range[range]) + 1
+const uint8_t kVP8NewRange[128] = {
+ 127, 127, 191, 127, 159, 191, 223, 127,
+ 143, 159, 175, 191, 207, 223, 239, 127,
+ 135, 143, 151, 159, 167, 175, 183, 191,
+ 199, 207, 215, 223, 231, 239, 247, 127,
+ 131, 135, 139, 143, 147, 151, 155, 159,
+ 163, 167, 171, 175, 179, 183, 187, 191,
+ 195, 199, 203, 207, 211, 215, 219, 223,
+ 227, 231, 235, 239, 243, 247, 251, 127,
+ 129, 131, 133, 135, 137, 139, 141, 143,
+ 145, 147, 149, 151, 153, 155, 157, 159,
+ 161, 163, 165, 167, 169, 171, 173, 175,
+ 177, 179, 181, 183, 185, 187, 189, 191,
+ 193, 195, 197, 199, 201, 203, 205, 207,
+ 209, 211, 213, 215, 217, 219, 221, 223,
+ 225, 227, 229, 231, 233, 235, 237, 239,
+ 241, 243, 245, 247, 249, 251, 253, 127
+};
+
+void VP8LoadFinalBytes(VP8BitReader* const br) {
+ assert(br != NULL && br->buf_ != NULL);
+ // Only read 8bits at a time
+ if (br->buf_ < br->buf_end_) {
+ br->bits_ += 8;
+ br->value_ = (bit_t)(*br->buf_++) | (br->value_ << 8);
+ } else if (!br->eof_) {
+ br->value_ <<= 8;
+ br->bits_ += 8;
+ br->eof_ = 1;
+ } else {
+ br->bits_ = 0; // This is to avoid undefined behaviour with shifts.
+ }
+}
+
+//------------------------------------------------------------------------------
+// Higher-level calls
+
+uint32_t VP8GetValue(VP8BitReader* const br, int bits) {
+ uint32_t v = 0;
+ while (bits-- > 0) {
+ v |= VP8GetBit(br, 0x80) << bits;
+ }
+ return v;
+}
+
+int32_t VP8GetSignedValue(VP8BitReader* const br, int bits) {
+ const int value = VP8GetValue(br, bits);
+ return VP8Get(br) ? -value : value;
+}
+
+//------------------------------------------------------------------------------
+// VP8LBitReader
+
+#define VP8L_LOG8_WBITS 4 // Number of bytes needed to store VP8L_WBITS bits.
+
+#if defined(__arm__) || defined(_M_ARM) || defined(__aarch64__) || \
+ defined(__i386__) || defined(_M_IX86) || \
+ defined(__x86_64__) || defined(_M_X64)
+#define VP8L_USE_FAST_LOAD
+#endif
+
+static const uint32_t kBitMask[VP8L_MAX_NUM_BIT_READ + 1] = {
+ 0,
+ 0x000001, 0x000003, 0x000007, 0x00000f,
+ 0x00001f, 0x00003f, 0x00007f, 0x0000ff,
+ 0x0001ff, 0x0003ff, 0x0007ff, 0x000fff,
+ 0x001fff, 0x003fff, 0x007fff, 0x00ffff,
+ 0x01ffff, 0x03ffff, 0x07ffff, 0x0fffff,
+ 0x1fffff, 0x3fffff, 0x7fffff, 0xffffff
+};
+
+void VP8LInitBitReader(VP8LBitReader* const br, const uint8_t* const start,
+ size_t length) {
+ size_t i;
+ vp8l_val_t value = 0;
+ assert(br != NULL);
+ assert(start != NULL);
+ assert(length < 0xfffffff8u); // can't happen with a RIFF chunk.
+
+ br->len_ = length;
+ br->val_ = 0;
+ br->bit_pos_ = 0;
+ br->eos_ = 0;
+
+ if (length > sizeof(br->val_)) {
+ length = sizeof(br->val_);
+ }
+ for (i = 0; i < length; ++i) {
+ value |= (vp8l_val_t)start[i] << (8 * i);
+ }
+ br->val_ = value;
+ br->pos_ = length;
+ br->buf_ = start;
+}
+
+void VP8LBitReaderSetBuffer(VP8LBitReader* const br,
+ const uint8_t* const buf, size_t len) {
+ assert(br != NULL);
+ assert(buf != NULL);
+ assert(len < 0xfffffff8u); // can't happen with a RIFF chunk.
+ br->buf_ = buf;
+ br->len_ = len;
+ // pos_ > len_ should be considered a param error.
+ br->eos_ = (br->pos_ > br->len_) || VP8LIsEndOfStream(br);
+}
+
+static void VP8LSetEndOfStream(VP8LBitReader* const br) {
+ br->eos_ = 1;
+ br->bit_pos_ = 0; // To avoid undefined behaviour with shifts.
+}
+
+// If not at EOS, reload up to VP8L_LBITS byte-by-byte
+static void ShiftBytes(VP8LBitReader* const br) {
+ while (br->bit_pos_ >= 8 && br->pos_ < br->len_) {
+ br->val_ >>= 8;
+ br->val_ |= ((vp8l_val_t)br->buf_[br->pos_]) << (VP8L_LBITS - 8);
+ ++br->pos_;
+ br->bit_pos_ -= 8;
+ }
+ if (VP8LIsEndOfStream(br)) {
+ VP8LSetEndOfStream(br);
+ }
+}
+
+void VP8LDoFillBitWindow(VP8LBitReader* const br) {
+ assert(br->bit_pos_ >= VP8L_WBITS);
+#if defined(VP8L_USE_FAST_LOAD)
+ if (br->pos_ + sizeof(br->val_) < br->len_) {
+ br->val_ >>= VP8L_WBITS;
+ br->bit_pos_ -= VP8L_WBITS;
+ br->val_ |= (vp8l_val_t)HToLE32(WebPMemToUint32(br->buf_ + br->pos_)) <<
+ (VP8L_LBITS - VP8L_WBITS);
+ br->pos_ += VP8L_LOG8_WBITS;
+ return;
+ }
+#endif
+ ShiftBytes(br); // Slow path.
+}
+
+uint32_t VP8LReadBits(VP8LBitReader* const br, int n_bits) {
+ assert(n_bits >= 0);
+ // Flag an error if end_of_stream or n_bits is more than allowed limit.
+ if (!br->eos_ && n_bits <= VP8L_MAX_NUM_BIT_READ) {
+ const uint32_t val = VP8LPrefetchBits(br) & kBitMask[n_bits];
+ const int new_bits = br->bit_pos_ + n_bits;
+ br->bit_pos_ = new_bits;
+ ShiftBytes(br);
+ return val;
+ } else {
+ VP8LSetEndOfStream(br);
+ return 0;
+ }
+}
+
+//------------------------------------------------------------------------------
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-15 01:55:24 +0000