gstreamer/libs/getbits/gstgetbits_generic.c

#include <glib.h>

#include "gstgetbits.h"

unsigned long _gst_getbits_int_cb(gst_getbits_t *gb, unsigned long bits);
unsigned long _gst_get1bit_int(gst_getbits_t *gb, unsigned long bits);
unsigned long _gst_getbits_int(gst_getbits_t *gb, unsigned long bits);
unsigned long _gst_getbits_fast_int(gst_getbits_t *gb, unsigned long bits);
unsigned long _gst_showbits_int(gst_getbits_t *gb, unsigned long bits);
void _gst_flushbits_int(gst_getbits_t *gb, unsigned long bits);
void _gst_getbits_back_int(gst_getbits_t *gb, unsigned long bits);


unsigned long _gst_getbits_int_cb(gst_getbits_t *gb, unsigned long bits) {
  int result;
  int bitsleft;

  //printf("gst_getbits%lu %ld %p %08x\n", bits, gb->bits, gb->ptr, gb->dword);

  if (!bits) return 0;

  gb->bits -= bits;
  result = gb->dword >> (32-bits);

  if (gb->bits < 0) {
    
    gb->ptr += 4;

    bitsleft = (gb->endptr - gb->ptr)*8;
    bits = -gb->bits;
    gb->bits += (bitsleft>32? 32 : bitsleft); 
    
    if (gb->endptr <= gb->ptr) {
      (gb->callback)(gb, gb->data);
      gb->bits -= bits;
    }
    gb->dword = swab32(*((unsigned long *)(gb->ptr)));

    result |= (gb->dword >> (32-bits));
  }
  gb->dword <<= bits;

  return result;
}

unsigned long _gst_get1bit_int(gst_getbits_t *gb, unsigned long bits) {
  unsigned char rval;

  rval = *gb->ptr << gb->bits;

  gb->bits++;
  gb->ptr += (gb->bits>>3);
  gb->bits &= 0x7;

  DEBUG("getbits%d, %08x\n", bits, rval);
  return rval>>7;
}

unsigned long _gst_getbits_int(gst_getbits_t *gb, unsigned long bits) {
  unsigned long rval;

  if (bits == 0) return 0;

  rval = swab32(*((unsigned long *)(gb->ptr)));
  rval <<= gb->bits;

  gb->bits += bits;

  rval >>= (32-bits);
  gb->ptr += (gb->bits>>3);
  gb->bits &= 0x7;

  DEBUG("getbits%d, %08x\n", bits, rval);
  return rval;
}

unsigned long _gst_getbits_fast_int(gst_getbits_t *gb, unsigned long bits) {
  unsigned long rval;

  rval = (unsigned char) (gb->ptr[0] << gb->bits);
  rval |= ((unsigned int) gb->ptr[1] << gb->bits)>>8;
  rval <<= bits;
  rval >>= 8;

  gb->bits += bits;
  gb->ptr += (gb->bits>>3);
  gb->bits &= 0x7;

  DEBUG("getbits%d, %08x\n", bits, rval);
  return rval;
}

unsigned long _gst_showbits_int(gst_getbits_t *gb, unsigned long bits) {
  unsigned long rval;

  if (bits == 0) return 0;

  rval = swab32(*((unsigned long *)(gb->ptr)));
  rval <<= gb->bits;
  rval >>= (32-bits);

  DEBUG("showbits%d, %08x\n", bits, rval);
  return rval;
}

void _gst_flushbits_int(gst_getbits_t *gb, unsigned long bits) {
  gb->bits += bits;
  gb->ptr += (gb->bits>>3);
  gb->bits &= 0x7;
  DEBUG("flushbits%d\n", bits);
}

void _gst_getbits_back_int(gst_getbits_t *gb, unsigned long bits) {
  gb->bits -= bits;
  gb->ptr += (gb->bits>>3);
  gb->bits &= 0x7;
}