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