Chris@69: /* Copyright (c) 2001-2011 Timothy B. Terriberry
Chris@69:    Copyright (c) 2008-2009 Xiph.Org Foundation */
Chris@69: /*
Chris@69:    Redistribution and use in source and binary forms, with or without
Chris@69:    modification, are permitted provided that the following conditions
Chris@69:    are met:
Chris@69: 
Chris@69:    - Redistributions of source code must retain the above copyright
Chris@69:    notice, this list of conditions and the following disclaimer.
Chris@69: 
Chris@69:    - Redistributions in binary form must reproduce the above copyright
Chris@69:    notice, this list of conditions and the following disclaimer in the
Chris@69:    documentation and/or other materials provided with the distribution.
Chris@69: 
Chris@69:    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
Chris@69:    ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
Chris@69:    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
Chris@69:    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
Chris@69:    OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
Chris@69:    EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
Chris@69:    PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
Chris@69:    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
Chris@69:    LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
Chris@69:    NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
Chris@69:    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Chris@69: */
Chris@69: 
Chris@69: #include "opus_types.h"
Chris@69: #include "opus_defines.h"
Chris@69: 
Chris@69: #if !defined(_entcode_H)
Chris@69: # define _entcode_H (1)
Chris@69: # include <limits.h>
Chris@69: # include <stddef.h>
Chris@69: # include "ecintrin.h"
Chris@69: 
Chris@69: extern const opus_uint32 SMALL_DIV_TABLE[129];
Chris@69: 
Chris@69: #ifdef OPUS_ARM_ASM
Chris@69: #define USE_SMALL_DIV_TABLE
Chris@69: #endif
Chris@69: 
Chris@69: /*OPT: ec_window must be at least 32 bits, but if you have fast arithmetic on a
Chris@69:    larger type, you can speed up the decoder by using it here.*/
Chris@69: typedef opus_uint32           ec_window;
Chris@69: typedef struct ec_ctx         ec_ctx;
Chris@69: typedef struct ec_ctx         ec_enc;
Chris@69: typedef struct ec_ctx         ec_dec;
Chris@69: 
Chris@69: # define EC_WINDOW_SIZE ((int)sizeof(ec_window)*CHAR_BIT)
Chris@69: 
Chris@69: /*The number of bits to use for the range-coded part of unsigned integers.*/
Chris@69: # define EC_UINT_BITS   (8)
Chris@69: 
Chris@69: /*The resolution of fractional-precision bit usage measurements, i.e.,
Chris@69:    3 => 1/8th bits.*/
Chris@69: # define BITRES 3
Chris@69: 
Chris@69: /*The entropy encoder/decoder context.
Chris@69:   We use the same structure for both, so that common functions like ec_tell()
Chris@69:    can be used on either one.*/
Chris@69: struct ec_ctx{
Chris@69:    /*Buffered input/output.*/
Chris@69:    unsigned char *buf;
Chris@69:    /*The size of the buffer.*/
Chris@69:    opus_uint32    storage;
Chris@69:    /*The offset at which the last byte containing raw bits was read/written.*/
Chris@69:    opus_uint32    end_offs;
Chris@69:    /*Bits that will be read from/written at the end.*/
Chris@69:    ec_window      end_window;
Chris@69:    /*Number of valid bits in end_window.*/
Chris@69:    int            nend_bits;
Chris@69:    /*The total number of whole bits read/written.
Chris@69:      This does not include partial bits currently in the range coder.*/
Chris@69:    int            nbits_total;
Chris@69:    /*The offset at which the next range coder byte will be read/written.*/
Chris@69:    opus_uint32    offs;
Chris@69:    /*The number of values in the current range.*/
Chris@69:    opus_uint32    rng;
Chris@69:    /*In the decoder: the difference between the top of the current range and
Chris@69:       the input value, minus one.
Chris@69:      In the encoder: the low end of the current range.*/
Chris@69:    opus_uint32    val;
Chris@69:    /*In the decoder: the saved normalization factor from ec_decode().
Chris@69:      In the encoder: the number of oustanding carry propagating symbols.*/
Chris@69:    opus_uint32    ext;
Chris@69:    /*A buffered input/output symbol, awaiting carry propagation.*/
Chris@69:    int            rem;
Chris@69:    /*Nonzero if an error occurred.*/
Chris@69:    int            error;
Chris@69: };
Chris@69: 
Chris@69: static OPUS_INLINE opus_uint32 ec_range_bytes(ec_ctx *_this){
Chris@69:   return _this->offs;
Chris@69: }
Chris@69: 
Chris@69: static OPUS_INLINE unsigned char *ec_get_buffer(ec_ctx *_this){
Chris@69:   return _this->buf;
Chris@69: }
Chris@69: 
Chris@69: static OPUS_INLINE int ec_get_error(ec_ctx *_this){
Chris@69:   return _this->error;
Chris@69: }
Chris@69: 
Chris@69: /*Returns the number of bits "used" by the encoded or decoded symbols so far.
Chris@69:   This same number can be computed in either the encoder or the decoder, and is
Chris@69:    suitable for making coding decisions.
Chris@69:   Return: The number of bits.
Chris@69:           This will always be slightly larger than the exact value (e.g., all
Chris@69:            rounding error is in the positive direction).*/
Chris@69: static OPUS_INLINE int ec_tell(ec_ctx *_this){
Chris@69:   return _this->nbits_total-EC_ILOG(_this->rng);
Chris@69: }
Chris@69: 
Chris@69: /*Returns the number of bits "used" by the encoded or decoded symbols so far.
Chris@69:   This same number can be computed in either the encoder or the decoder, and is
Chris@69:    suitable for making coding decisions.
Chris@69:   Return: The number of bits scaled by 2**BITRES.
Chris@69:           This will always be slightly larger than the exact value (e.g., all
Chris@69:            rounding error is in the positive direction).*/
Chris@69: opus_uint32 ec_tell_frac(ec_ctx *_this);
Chris@69: 
Chris@69: /* Tested exhaustively for all n and for 1<=d<=256 */
Chris@69: static OPUS_INLINE opus_uint32 celt_udiv(opus_uint32 n, opus_uint32 d) {
Chris@69:    celt_sig_assert(d>0);
Chris@69: #ifdef USE_SMALL_DIV_TABLE
Chris@69:    if (d>256)
Chris@69:       return n/d;
Chris@69:    else {
Chris@69:       opus_uint32 t, q;
Chris@69:       t = EC_ILOG(d&-d);
Chris@69:       q = (opus_uint64)SMALL_DIV_TABLE[d>>t]*(n>>(t-1))>>32;
Chris@69:       return q+(n-q*d >= d);
Chris@69:    }
Chris@69: #else
Chris@69:    return n/d;
Chris@69: #endif
Chris@69: }
Chris@69: 
Chris@69: static OPUS_INLINE opus_int32 celt_sudiv(opus_int32 n, opus_int32 d) {
Chris@69:    celt_sig_assert(d>0);
Chris@69: #ifdef USE_SMALL_DIV_TABLE
Chris@69:    if (n<0)
Chris@69:       return -(opus_int32)celt_udiv(-n, d);
Chris@69:    else
Chris@69:       return celt_udiv(n, d);
Chris@69: #else
Chris@69:    return n/d;
Chris@69: #endif
Chris@69: }
Chris@69: 
Chris@69: #endif