159 lines
4.2 KiB
C
159 lines
4.2 KiB
C
/*
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* SpanDSP - a series of DSP components for telephony
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*
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* bitstream.c - Bitstream composition and decomposition routines.
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*
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* Written by Steve Underwood <steveu@coppice.org>
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*
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* Copyright (C) 2006 Steve Underwood
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License version 2.1,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/*! \file */
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#if defined(HAVE_CONFIG_H)
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#include "config.h"
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#endif
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#include <inttypes.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include "spandsp/telephony.h"
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#include "spandsp/bitstream.h"
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#include "spandsp/private/bitstream.h"
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SPAN_DECLARE(void) bitstream_put(bitstream_state_t *s, uint8_t **c, uint32_t value, int bits)
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{
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value &= ((1 << bits) - 1);
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if (s->lsb_first)
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{
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if (s->residue + bits <= 32)
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{
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s->bitstream |= (value << s->residue);
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s->residue += bits;
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}
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while (s->residue >= 8)
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{
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s->residue -= 8;
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*(*c)++ = (uint8_t) (s->bitstream & 0xFF);
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s->bitstream >>= 8;
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}
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}
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else
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{
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if (s->residue + bits <= 32)
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{
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s->bitstream = (s->bitstream << bits) | value;
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s->residue += bits;
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}
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while (s->residue >= 8)
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{
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s->residue -= 8;
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*(*c)++ = (uint8_t) ((s->bitstream >> s->residue) & 0xFF);
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}
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}
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(void) bitstream_emit(bitstream_state_t *s, uint8_t **c)
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{
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uint32_t bitstream;
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if (s->residue > 0)
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{
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bitstream = s->bitstream & ((1 << s->residue) - 1);
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if (s->lsb_first)
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*(*c) = (uint8_t) bitstream;
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else
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*(*c) = (uint8_t) (bitstream << (8 - s->residue));
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}
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(void) bitstream_flush(bitstream_state_t *s, uint8_t **c)
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{
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if (s->residue > 0)
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{
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bitstream_emit(s, c);
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(*c)++;
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s->residue = 0;
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}
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s->bitstream = 0;
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(uint32_t) bitstream_get(bitstream_state_t *s, const uint8_t **c, int bits)
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{
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uint32_t x;
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if (s->lsb_first)
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{
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while (s->residue < bits)
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{
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s->bitstream |= (((uint32_t) *(*c)++) << s->residue);
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s->residue += 8;
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}
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s->residue -= bits;
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x = s->bitstream & ((1 << bits) - 1);
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s->bitstream >>= bits;
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}
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else
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{
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while (s->residue < bits)
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{
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s->bitstream = (s->bitstream << 8) | ((uint32_t) *(*c)++);
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s->residue += 8;
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}
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s->residue -= bits;
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x = (s->bitstream >> s->residue) & ((1 << bits) - 1);
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}
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return x;
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(bitstream_state_t *) bitstream_init(bitstream_state_t *s, int lsb_first)
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{
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if (s == NULL)
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{
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if ((s = (bitstream_state_t *) malloc(sizeof(*s))) == NULL)
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return NULL;
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}
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s->bitstream = 0;
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s->residue = 0;
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s->lsb_first = lsb_first;
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return s;
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(int) bitstream_release(bitstream_state_t *s)
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{
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return 0;
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(int) bitstream_free(bitstream_state_t *s)
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{
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if (s)
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free(s);
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return 0;
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}
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/*- End of function --------------------------------------------------------*/
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/*- End of file ------------------------------------------------------------*/
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