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