gstreamer/libs/putbits/gstputbits.c

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/* putbits.c, bit-level output */
/* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */
/*
* Disclaimer of Warranty
*
* These software programs are available to the user without any license fee or
* royalty on an "as is" basis. The MPEG Software Simulation Group disclaims
* any and all warranties, whether express, implied, or statuary, including any
* implied warranties or merchantability or of fitness for a particular
* purpose. In no event shall the copyright-holder be liable for any
* incidental, punitive, or consequential damages of any kind whatsoever
* arising from the use of these programs.
*
* This disclaimer of warranty extends to the user of these programs and user's
* customers, employees, agents, transferees, successors, and assigns.
*
* The MPEG Software Simulation Group does not represent or warrant that the
* programs furnished hereunder are free of infringement of any third-party
* patents.
*
* Commercial implementations of MPEG-1 and MPEG-2 video, including shareware,
* are subject to royalty fees to patent holders. Many of these patents are
* general enough such that they are unavoidable regardless of implementation
* design.
*
*/
#include <stdlib.h>
#include <stdio.h>
#include "gstputbits.h"
/* initialize buffer, call once before first putbits or alignbits */
void gst_putbits_init(gst_putbits_t *pb)
{
pb->outcnt = 8;
pb->bytecnt = 0;
pb->outbase = 0;
}
void gst_putbits_new_empty_buffer(gst_putbits_t *pb, int len)
{
pb->outbfr = pb->outbase = malloc(len);
pb->temp = 0;
pb->len = len;
pb->newlen = 0;
pb->outcnt = 8;
}
void gst_putbits_new_buffer(gst_putbits_t *pb, unsigned char *buffer, int len)
{
pb->outbfr = buffer;
pb->temp = 0;
pb->outcnt = 8;
pb->bytecnt = 0;
pb->len = len;
}
/* write rightmost n (0<=n<=32) bits of val to outfile */
void gst_putbits(gst_putbits_t *pb, int val, int n)
{
int i;
unsigned int mask;
//printf("putbits: %p %08x %d %d %d\n", pb, val, n, pb->outcnt, pb->newlen);
mask = 1 << (n-1); /* selects first (leftmost) bit */
for (i=0; i<n; i++)
{
pb->temp <<= 1;
if (val & mask)
pb->temp|= 1;
mask >>= 1; /* select next bit */
pb->outcnt--;
if (pb->outcnt==0) /* 8 bit buffer full */
{
pb->len--;
pb->newlen++;
*(pb->outbfr++) = pb->temp;
pb->outcnt = 8;
pb->bytecnt++;
}
}
}
/* zero bit stuffing to next byte boundary (5.2.3, 6.2.1) */
void gst_putbits_align(gst_putbits_t *pb)
{
if (pb->outcnt!=8)
gst_putbits(pb, 0, pb->outcnt);
}
/* return total number of generated bits */
int gst_putbits_bitcount(gst_putbits_t *pb)
{
return 8*pb->bytecnt + (8-pb->outcnt);
}