Initial community commit

Src/external_dependencies/openmpt-trunk/include/opus/celt/entcode.h

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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_sig_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_sig_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