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001bbb7002
Original commit message from CVS: Added general IDCT library. Added IEEE testbed. Update to the windows codec loader. fixes in the riff parser/encoder. cleanup in the getbits/putbits API.
248 lines
7.8 KiB
C
248 lines
7.8 KiB
C
#include <byteswap.h>
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#include "gstgetbits.h"
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unsigned long gst_getbits_nBitMask[] = {
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0x00000000, 0x80000000, 0xc0000000, 0xe0000000,
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0xf0000000, 0xf8000000, 0xfc000000, 0xfe000000,
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0xff000000, 0xff800000, 0xffc00000, 0xffe00000,
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0xfff00000, 0xfff80000, 0xfffc0000, 0xfffe0000,
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0xffff0000, 0xffff8000, 0xffffc000, 0xffffe000,
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0xfffff000, 0xfffff800, 0xfffffc00, 0xfffffe00,
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0xffffff00, 0xffffff80, 0xffffffc0, 0xffffffe0,
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0xfffffff0, 0xfffffff8, 0xfffffffc, 0xfffffffe};
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unsigned long _getbits_masks[] = {
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0x00000000,
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0x00000001, 0x00000003, 0x00000007, 0x0000000f,
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0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff,
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0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff,
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0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff,
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0x0001ffff, 0x0003ffff, 0x0007ffff, 0x000fffff,
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0x001fffff, 0x003fffff, 0x007fffff, 0x00ffffff,
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0x01ffffff, 0x03ffffff, 0x07ffffff, 0x0fffffff,
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0x1fffffff, 0x3fffffff, 0x7fffffff, 0xffffffff,
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};
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#ifdef HAVE_LIBMMX
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unsigned long _getbits_64_minus_index[] = {
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64,63,62,61,60,59,58,57,56,55,54,53,52,51,50,49,48,47,46,45,44,43,42,41,
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40,39,38,37,36,35,34,33,32,31,30,29,28,27,26,25,24,23,22,21,20,19,18,17,
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16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1 };
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/* this routine taken from Intel AppNote AP-527:
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"Using MMX[tm] Instructions to Get Bits From a Data Stream"
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written in C with libmmx to *closely* mimic Intel's ASM implementation
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this isn't as cycle-efficient, due to the simple fact that I must call
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emms() at the end. all state must be kept in *gb, not in registers */
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unsigned long getbits_mmx(gst_getbits_t *gb,unsigned long bits) {
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signed long remaining;
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unsigned long result;
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/* NOTE: this is a code-size optimization Intel seems to have missed!
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according to the MMX Programmer's Reference Manual, Chapter 5,
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neither movd nor movq have any effect on the flags. that means you
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can put them before the sub and jl in their code, which I've done
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symbolically in this C code. gcc is probably going to lose horribly,
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I'll do an inline asm version later. I've a point to prove ;-) */
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/* find the right shift value, put it in mm3 */
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movd_m2r(_getbits_64_minus_index[bits],mm3);
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/* load the current quadword into mm0 */
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movq_m2r(gb->qword,mm0);
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/* copy it to mm2 */
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movq_r2r(mm0,mm2);
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remaining = gb->bits - bits;
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if (remaining <= 0) {
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unsigned long dword1,dword2;
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/* shift the pointer by 64 bits (8 bytes) */
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gb->ptr += 8;
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/* add 64 to bits remaining, to bring it positive */
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remaining += 64;
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/* grab the first 32 bits from the buffer and swap them around */
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dword1 = bswap_32(*(gb->ptr-8));
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/* grab the second 32 bits, swap */
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dword2 = bswap_32(*(gb->ptr-4));
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/* put second dword in mm4 */
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movd_m2r(dword2,mm4);
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/* shift mm2 over to make room for new bits */
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psrlq_r2r(mm3,mm2);
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/* put first dword in mm1 */
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movd_m2r(dword1,mm1);
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/* shift second dword up 32 bits */
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psrlq_i2r(32,mm4);
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/* put the shift counter in mm3 */
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movd_m2r(remaining,mm3);
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/* combine the swapped data in mm4 */
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por_r2r(mm1,mm4);
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/* save off the bits in mm4 to mm0 */
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movq_r2r(mm4,mm0);
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/* get the new low-order bits in mm4, shifted by 'mm3' */
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psrlq_r2r(mm3,mm4);
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/* save off new remaining bits */
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gb->bits = remaining;
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/* combine bits into mm2 */
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por_r2r(mm2,mm4);
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/* save off the result */
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movd_r2m(mm2,result);
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/* get rid of the bits we just read */
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psllq_r2r(mm1,mm0);
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/* save off mm0 */
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movq_r2m(mm0,gb->qword);
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/* finished with MMX */
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emms();
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/* we have what we came for */
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return(result);
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} else {
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/* load the number of bits requested into mm1 */
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movd_m2r(bits,mm1);
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/* shift the quadword in mm2 by 'mm3' bits */
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psrlq_r2r(mm3,mm2);
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/* update the number of valid bits */
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gb->bits = remaining;
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/* save off the remaining bits */
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movd_r2m(mm2,result);
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/* discard those bits in mm0 */
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psllq_r2r(mm1,mm0);
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/* save off mm0 */
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movq_r2m(mm0,gb->qword);
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/* finished with MMX */
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emms();
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/* we have what we came for */
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return(result);
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}
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}
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#endif /* HAVE_LIBMMX */
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unsigned long getbits_int(gst_getbits_t *gb,unsigned long bits) {
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int remaining;
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int result = 0;
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if (bits == 0) {
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// fprintf(stderr,"getbits(0) = 0\n");
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return 0;
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}
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remaining = gb->bits - bits;
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if (remaining < 0) {
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/* how many bits are left to get? */
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remaining = -remaining;
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// printf("have to get %d more bits from next dword\n",remaining);
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/* move what's left over to accomodate the new stuff */
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result = gb->dword >> (32 - bits);
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// printf("have \t\t%s from previous dword\n",print_bits(result));
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/* get the new word into the buffer */
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// fprintf(stderr,"getbits: incrementing %p by 4\n",gb->ptr);
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gb->ptr += 4;
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gb->dword = bswap_32(*((unsigned long *)(gb->ptr)));
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// gb->dword = *((unsigned char *)(gb->ptr)) << 24 |
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// *((unsigned char *)(gb->ptr)+1) << 16 |
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// *((unsigned char *)(gb->ptr)+2) << 8 |
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// *((unsigned char *)(gb->ptr)+3);
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// gb->dword = *((unsigned long *)(gb->ptr));
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gb->bits = 32;
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// fprintf(stderr,"got new dword %08x\n",gb->dword);
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/* & in the right number of bits */
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result |= (gb->dword >> (32 - remaining));
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/* shift the buffer over */
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gb->dword <<= remaining;
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/* record how many bits are left */
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gb->bits -= remaining;
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} else {
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result = gb->dword >> (32 - bits);
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gb->dword <<= bits;
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gb->bits -= bits;
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// printf("have %d bits left\n",gb->bits);
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}
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// printf("have \t\t%s left\n",print_bits(gb->dword));
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// fprintf(stderr,"getbits.c:getbits(%ld) = %d\n",bits,result);
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return result;
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}
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void getbits_back_int(gst_getbits_t *gb,unsigned long bits) {
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fprintf(stderr,"getbits.c:getbits_back(%lu)\n",bits);
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// moving within the same dword...
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if ((bits + gb->bits) <= 32) {
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fprintf(stderr,"moving back %lu bits in the same dword\n",bits);
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gb->bits += bits;
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// otherwise we're going to have move the pointer (ick)
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} else {
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// rare case where we're moving a multiple of 32 bits...
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if ((bits % 32) == 0) {
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fprintf(stderr,"moving back exactly %lu dwords\n",bits/32);
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gb->ptr -= (bits / 8);
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// we have to both shift bits and the pointer (NOOOOOOO!)
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} else {
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// strip off the first dword
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bits -= (32 - gb->bits);
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gb->ptr -= 4;
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// now strip off as many others as necessary
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gb->ptr -= 4 * (bits/32);
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// and set the bits to what's left
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gb->bits = bits % 32;
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fprintf(stderr,"moved back %lu bytes to %p\n",4 * ((bits/32)+1),gb->ptr);
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}
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}
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gb->dword = bswap_32(*((unsigned long *)(gb->ptr)));
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fprintf(stderr,"orignal new loaded word is %08lx\n",gb->dword);
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gb->dword <<= (32 - gb->bits);
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fprintf(stderr,"shifted (by %lu) word is %08lx\n",gb->bits,gb->dword);
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}
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void getbits_byteback_int(gst_getbits_t *gb,unsigned long bytes) {
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fprintf(stderr,"getbits.c:getbits_byteback(%lu)\n",bytes);
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getbits_back_int(gb,bytes*8);
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gb->bits = gb->bits & ~0x07;
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}
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int getbits_offset(gst_getbits_t *gb) {
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fprintf(stderr,"getbits.c:getbits_offset() = %lu\n",gb->bits % 8);
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return gb->bits % 8;
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}
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/* initialize the getbits structure with the proper getbits func */
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void getbits_init(gst_getbits_t *gb) {
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gb->ptr = NULL;
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gb->bits = 0;
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#ifdef HAVE_LIBMMX
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if (1) {
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gb->getbits = getbits_mmx;
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// gb->backbits = getbits_back_mmx;
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// gb->backbytes = getbits_byteback_mmx;
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} else
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#endif /* HAVE_LIBMMX */
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{
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gb->getbits = getbits_int;
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gb->backbits = getbits_back_int;
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gb->backbytes = getbits_byteback_int;
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}
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}
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/* set up the getbits structure with a new buffer */
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void getbits_newbuf(gst_getbits_t *gb,unsigned char *buffer) {
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gb->ptr = buffer - 4;
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// fprintf(stderr,"setting ptr to %p\n",gb->ptr);
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gb->bits = 0;
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gb->dword = 0;
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#ifdef HAVE_LIBMMX
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// gb->qword = 0;
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#endif /* HAVE_LIBMMX */
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}
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