cannam@154: /* Copyright (c) 2001-2011 Timothy B. Terriberry
cannam@154:    Copyright (c) 2008-2009 Xiph.Org Foundation */
cannam@154: /*
cannam@154:    Redistribution and use in source and binary forms, with or without
cannam@154:    modification, are permitted provided that the following conditions
cannam@154:    are met:
cannam@154: 
cannam@154:    - Redistributions of source code must retain the above copyright
cannam@154:    notice, this list of conditions and the following disclaimer.
cannam@154: 
cannam@154:    - Redistributions in binary form must reproduce the above copyright
cannam@154:    notice, this list of conditions and the following disclaimer in the
cannam@154:    documentation and/or other materials provided with the distribution.
cannam@154: 
cannam@154:    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
cannam@154:    ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
cannam@154:    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
cannam@154:    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
cannam@154:    OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
cannam@154:    EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
cannam@154:    PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
cannam@154:    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
cannam@154:    LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
cannam@154:    NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
cannam@154:    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
cannam@154: */
cannam@154: 
cannam@154: #include "opus_types.h"
cannam@154: #include "opus_defines.h"
cannam@154: 
cannam@154: #if !defined(_entcode_H)
cannam@154: # define _entcode_H (1)
cannam@154: # include <limits.h>
cannam@154: # include <stddef.h>
cannam@154: # include "ecintrin.h"
cannam@154: 
cannam@154: extern const opus_uint32 SMALL_DIV_TABLE[129];
cannam@154: 
cannam@154: #ifdef OPUS_ARM_ASM
cannam@154: #define USE_SMALL_DIV_TABLE
cannam@154: #endif
cannam@154: 
cannam@154: /*OPT: ec_window must be at least 32 bits, but if you have fast arithmetic on a
cannam@154:    larger type, you can speed up the decoder by using it here.*/
cannam@154: typedef opus_uint32           ec_window;
cannam@154: typedef struct ec_ctx         ec_ctx;
cannam@154: typedef struct ec_ctx         ec_enc;
cannam@154: typedef struct ec_ctx         ec_dec;
cannam@154: 
cannam@154: # define EC_WINDOW_SIZE ((int)sizeof(ec_window)*CHAR_BIT)
cannam@154: 
cannam@154: /*The number of bits to use for the range-coded part of unsigned integers.*/
cannam@154: # define EC_UINT_BITS   (8)
cannam@154: 
cannam@154: /*The resolution of fractional-precision bit usage measurements, i.e.,
cannam@154:    3 => 1/8th bits.*/
cannam@154: # define BITRES 3
cannam@154: 
cannam@154: /*The entropy encoder/decoder context.
cannam@154:   We use the same structure for both, so that common functions like ec_tell()
cannam@154:    can be used on either one.*/
cannam@154: struct ec_ctx{
cannam@154:    /*Buffered input/output.*/
cannam@154:    unsigned char *buf;
cannam@154:    /*The size of the buffer.*/
cannam@154:    opus_uint32    storage;
cannam@154:    /*The offset at which the last byte containing raw bits was read/written.*/
cannam@154:    opus_uint32    end_offs;
cannam@154:    /*Bits that will be read from/written at the end.*/
cannam@154:    ec_window      end_window;
cannam@154:    /*Number of valid bits in end_window.*/
cannam@154:    int            nend_bits;
cannam@154:    /*The total number of whole bits read/written.
cannam@154:      This does not include partial bits currently in the range coder.*/
cannam@154:    int            nbits_total;
cannam@154:    /*The offset at which the next range coder byte will be read/written.*/
cannam@154:    opus_uint32    offs;
cannam@154:    /*The number of values in the current range.*/
cannam@154:    opus_uint32    rng;
cannam@154:    /*In the decoder: the difference between the top of the current range and
cannam@154:       the input value, minus one.
cannam@154:      In the encoder: the low end of the current range.*/
cannam@154:    opus_uint32    val;
cannam@154:    /*In the decoder: the saved normalization factor from ec_decode().
cannam@154:      In the encoder: the number of oustanding carry propagating symbols.*/
cannam@154:    opus_uint32    ext;
cannam@154:    /*A buffered input/output symbol, awaiting carry propagation.*/
cannam@154:    int            rem;
cannam@154:    /*Nonzero if an error occurred.*/
cannam@154:    int            error;
cannam@154: };
cannam@154: 
cannam@154: static OPUS_INLINE opus_uint32 ec_range_bytes(ec_ctx *_this){
cannam@154:   return _this->offs;
cannam@154: }
cannam@154: 
cannam@154: static OPUS_INLINE unsigned char *ec_get_buffer(ec_ctx *_this){
cannam@154:   return _this->buf;
cannam@154: }
cannam@154: 
cannam@154: static OPUS_INLINE int ec_get_error(ec_ctx *_this){
cannam@154:   return _this->error;
cannam@154: }
cannam@154: 
cannam@154: /*Returns the number of bits "used" by the encoded or decoded symbols so far.
cannam@154:   This same number can be computed in either the encoder or the decoder, and is
cannam@154:    suitable for making coding decisions.
cannam@154:   Return: The number of bits.
cannam@154:           This will always be slightly larger than the exact value (e.g., all
cannam@154:            rounding error is in the positive direction).*/
cannam@154: static OPUS_INLINE int ec_tell(ec_ctx *_this){
cannam@154:   return _this->nbits_total-EC_ILOG(_this->rng);
cannam@154: }
cannam@154: 
cannam@154: /*Returns the number of bits "used" by the encoded or decoded symbols so far.
cannam@154:   This same number can be computed in either the encoder or the decoder, and is
cannam@154:    suitable for making coding decisions.
cannam@154:   Return: The number of bits scaled by 2**BITRES.
cannam@154:           This will always be slightly larger than the exact value (e.g., all
cannam@154:            rounding error is in the positive direction).*/
cannam@154: opus_uint32 ec_tell_frac(ec_ctx *_this);
cannam@154: 
cannam@154: /* Tested exhaustively for all n and for 1<=d<=256 */
cannam@154: static OPUS_INLINE opus_uint32 celt_udiv(opus_uint32 n, opus_uint32 d) {
cannam@154:    celt_sig_assert(d>0);
cannam@154: #ifdef USE_SMALL_DIV_TABLE
cannam@154:    if (d>256)
cannam@154:       return n/d;
cannam@154:    else {
cannam@154:       opus_uint32 t, q;
cannam@154:       t = EC_ILOG(d&-d);
cannam@154:       q = (opus_uint64)SMALL_DIV_TABLE[d>>t]*(n>>(t-1))>>32;
cannam@154:       return q+(n-q*d >= d);
cannam@154:    }
cannam@154: #else
cannam@154:    return n/d;
cannam@154: #endif
cannam@154: }
cannam@154: 
cannam@154: static OPUS_INLINE opus_int32 celt_sudiv(opus_int32 n, opus_int32 d) {
cannam@154:    celt_sig_assert(d>0);
cannam@154: #ifdef USE_SMALL_DIV_TABLE
cannam@154:    if (n<0)
cannam@154:       return -(opus_int32)celt_udiv(-n, d);
cannam@154:    else
cannam@154:       return celt_udiv(n, d);
cannam@154: #else
cannam@154:    return n/d;
cannam@154: #endif
cannam@154: }
cannam@154: 
cannam@154: #endif