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+/* Copyright (c) 2001-2011 Timothy B. Terriberry
+ Copyright (c) 2008-2009 Xiph.Org Foundation */
+/*
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions
+ are met:
+
+ - Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+
+ - Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include "opus_types.h"
+#include "opus_defines.h"
+
+#if !defined(_entcode_H)
+# define _entcode_H (1)
+# include <limits.h>
+# include <stddef.h>
+# include "ecintrin.h"
+
+extern const opus_uint32 SMALL_DIV_TABLE[129];
+
+#ifdef OPUS_ARM_ASM
+#define USE_SMALL_DIV_TABLE
+#endif
+
+/*OPT: ec_window must be at least 32 bits, but if you have fast arithmetic on a
+ larger type, you can speed up the decoder by using it here.*/
+typedef opus_uint32 ec_window;
+typedef struct ec_ctx ec_ctx;
+typedef struct ec_ctx ec_enc;
+typedef struct ec_ctx ec_dec;
+
+# define EC_WINDOW_SIZE ((int)sizeof(ec_window)*CHAR_BIT)
+
+/*The number of bits to use for the range-coded part of unsigned integers.*/
+# define EC_UINT_BITS (8)
+
+/*The resolution of fractional-precision bit usage measurements, i.e.,
+ 3 => 1/8th bits.*/
+# define BITRES 3
+
+/*The entropy encoder/decoder context.
+ We use the same structure for both, so that common functions like ec_tell()
+ can be used on either one.*/
+struct ec_ctx{
+ /*Buffered input/output.*/
+ unsigned char *buf;
+ /*The size of the buffer.*/
+ opus_uint32 storage;
+ /*The offset at which the last byte containing raw bits was read/written.*/
+ opus_uint32 end_offs;
+ /*Bits that will be read from/written at the end.*/
+ ec_window end_window;
+ /*Number of valid bits in end_window.*/
+ int nend_bits;
+ /*The total number of whole bits read/written.
+ This does not include partial bits currently in the range coder.*/
+ int nbits_total;
+ /*The offset at which the next range coder byte will be read/written.*/
+ opus_uint32 offs;
+ /*The number of values in the current range.*/
+ opus_uint32 rng;
+ /*In the decoder: the difference between the top of the current range and
+ the input value, minus one.
+ In the encoder: the low end of the current range.*/
+ opus_uint32 val;
+ /*In the decoder: the saved normalization factor from ec_decode().
+ In the encoder: the number of oustanding carry propagating symbols.*/
+ opus_uint32 ext;
+ /*A buffered input/output symbol, awaiting carry propagation.*/
+ int rem;
+ /*Nonzero if an error occurred.*/
+ int error;
+};
+
+static OPUS_INLINE opus_uint32 ec_range_bytes(ec_ctx *_this){
+ return _this->offs;
+}
+
+static OPUS_INLINE unsigned char *ec_get_buffer(ec_ctx *_this){
+ return _this->buf;
+}
+
+static OPUS_INLINE int ec_get_error(ec_ctx *_this){
+ return _this->error;
+}
+
+/*Returns the number of bits "used" by the encoded or decoded symbols so far.
+ This same number can be computed in either the encoder or the decoder, and is
+ suitable for making coding decisions.
+ Return: The number of bits.
+ This will always be slightly larger than the exact value (e.g., all
+ rounding error is in the positive direction).*/
+static OPUS_INLINE int ec_tell(ec_ctx *_this){
+ return _this->nbits_total-EC_ILOG(_this->rng);
+}
+
+/*Returns the number of bits "used" by the encoded or decoded symbols so far.
+ This same number can be computed in either the encoder or the decoder, and is
+ suitable for making coding decisions.
+ Return: The number of bits scaled by 2**BITRES.
+ This will always be slightly larger than the exact value (e.g., all
+ rounding error is in the positive direction).*/
+opus_uint32 ec_tell_frac(ec_ctx *_this);
+
+/* Tested exhaustively for all n and for 1<=d<=256 */
+static OPUS_INLINE opus_uint32 celt_udiv(opus_uint32 n, opus_uint32 d) {
+ celt_assert(d>0);
+#ifdef USE_SMALL_DIV_TABLE
+ if (d>256)
+ return n/d;
+ else {
+ opus_uint32 t, q;
+ t = EC_ILOG(d&-d);
+ q = (opus_uint64)SMALL_DIV_TABLE[d>>t]*(n>>(t-1))>>32;
+ return q+(n-q*d >= d);
+ }
+#else
+ return n/d;
+#endif
+}
+
+static OPUS_INLINE opus_int32 celt_sudiv(opus_int32 n, opus_int32 d) {
+ celt_assert(d>0);
+#ifdef USE_SMALL_DIV_TABLE
+ if (n<0)
+ return -(opus_int32)celt_udiv(-n, d);
+ else
+ return celt_udiv(n, d);
+#else
+ return n/d;
+#endif
+}
+
+#endif