--- bitstream.h 2002/11/17 00:57:57 1.14 +++ bitstream.h 2003/07/28 12:39:32 1.16.2.2 @@ -50,13 +50,15 @@ * exception also makes it possible to release a modified version which * carries forward this exception. * - * $Id: bitstream.h,v 1.14 2002/11/17 00:57:57 edgomez Exp $ + * $Id: bitstream.h,v 1.16.2.2 2003/07/28 12:39:32 edgomez Exp $ * ****************************************************************************/ #ifndef _BITSTREAM_H_ #define _BITSTREAM_H_ +#include + #include "../portab.h" #include "../decoder.h" #include "../encoder.h" @@ -66,7 +68,7 @@ * Constants ****************************************************************************/ -// comment any #defs we dont use +/* comment any #defs we dont use */ #define VIDOBJ_START_CODE 0x00000100 /* ..0x0000011f */ #define VIDOBJLAY_START_CODE 0x00000120 /* ..0x0000012f */ @@ -74,30 +76,30 @@ #define VISOBJSEQ_STOP_CODE 0x000001b1 /* ??? */ #define USERDATA_START_CODE 0x000001b2 #define GRPOFVOP_START_CODE 0x000001b3 -//#define VIDSESERR_ERROR_CODE 0x000001b4 +/*#define VIDSESERR_ERROR_CODE 0x000001b4 */ #define VISOBJ_START_CODE 0x000001b5 -//#define SLICE_START_CODE 0x000001b7 -//#define EXT_START_CODE 0x000001b8 +/*#define SLICE_START_CODE 0x000001b7 */ +/*#define EXT_START_CODE 0x000001b8 */ #define VISOBJ_TYPE_VIDEO 1 -//#define VISOBJ_TYPE_STILLTEXTURE 2 -//#define VISOBJ_TYPE_MESH 3 -//#define VISOBJ_TYPE_FBA 4 -//#define VISOBJ_TYPE_3DMESH 5 +/*#define VISOBJ_TYPE_STILLTEXTURE 2 */ +/*#define VISOBJ_TYPE_MESH 3 */ +/*#define VISOBJ_TYPE_FBA 4 */ +/*#define VISOBJ_TYPE_3DMESH 5 */ #define VIDOBJLAY_TYPE_SIMPLE 1 -//#define VIDOBJLAY_TYPE_SIMPLE_SCALABLE 2 +/*#define VIDOBJLAY_TYPE_SIMPLE_SCALABLE 2 */ #define VIDOBJLAY_TYPE_CORE 3 #define VIDOBJLAY_TYPE_MAIN 4 -//#define VIDOBJLAY_AR_SQUARE 1 -//#define VIDOBJLAY_AR_625TYPE_43 2 -//#define VIDOBJLAY_AR_525TYPE_43 3 -//#define VIDOBJLAY_AR_625TYPE_169 8 -//#define VIDOBJLAY_AR_525TYPE_169 9 +/*#define VIDOBJLAY_AR_SQUARE 1 */ +/*#define VIDOBJLAY_AR_625TYPE_43 2 */ +/*#define VIDOBJLAY_AR_525TYPE_43 3 */ +/*#define VIDOBJLAY_AR_625TYPE_169 8 */ +/*#define VIDOBJLAY_AR_525TYPE_169 9 */ #define VIDOBJLAY_AR_EXTPAR 15 @@ -113,15 +115,15 @@ #define READ_MARKER() BitstreamSkip(bs, 1) #define WRITE_MARKER() BitstreamPutBit(bs, 1) -// vop coding types -// intra, prediction, backward, sprite, not_coded +/* vop coding types */ +/* intra, prediction, backward, sprite, not_coded */ #define I_VOP 0 #define P_VOP 1 #define B_VOP 2 #define S_VOP 3 #define N_VOP 4 -// resync-specific +/* resync-specific */ #define NUMBITS_VP_RESYNC_MARKER 17 #define RESYNC_MARKER 1 @@ -134,7 +136,7 @@ read_video_packet_header(Bitstream *bs, const int addbits, int * quant); -// header stuff +/* header stuff */ int BitstreamReadHeaders(Bitstream * bs, DECODER * dec, uint32_t * rounding, @@ -165,23 +167,31 @@ uint32_t length) { uint32_t tmp; + size_t bitpos; + ptr_t adjbitstream = (ptr_t)bitstream; - bs->start = bs->tail = (uint32_t *) bitstream; + /* + * Start the stream on a uint32_t boundary, by rounding down to the + * previous uint32_t and skipping the intervening bytes. + */ + bitpos = ((sizeof(uint32_t)-1) & (size_t)bitstream); + adjbitstream = adjbitstream - bitpos; + bs->start = bs->tail = (uint32_t *) adjbitstream; - tmp = *(uint32_t *) bitstream; + tmp = *bs->start; #ifndef ARCH_IS_BIG_ENDIAN BSWAP(tmp); #endif bs->bufa = tmp; - tmp = *((uint32_t *) bitstream + 1); + tmp = *(bs->start + 1); #ifndef ARCH_IS_BIG_ENDIAN BSWAP(tmp); #endif bs->bufb = tmp; bs->buf = 0; - bs->pos = 0; + bs->pos = bs->initpos = bitpos*8; bs->length = length; } @@ -208,7 +218,7 @@ bs->bufb = tmp; bs->buf = 0; - bs->pos = 0; + bs->pos = bs->initpos; } @@ -253,7 +263,7 @@ } -// number of bits to next byte alignment +/* number of bits to next byte alignment */ static uint32_t __inline BitstreamNumBitsToByteAlign(Bitstream *bs) { @@ -262,7 +272,7 @@ } -// show nbits from next byte alignment +/* show nbits from next byte alignment */ static uint32_t __inline BitstreamShowBitsFromByteAlign(Bitstream *bs, int bits) { @@ -301,7 +311,7 @@ static uint32_t __inline BitstreamPos(const Bitstream * const bs) { - return 8 * ((ptr_t)bs->tail - (ptr_t)bs->start) + bs->pos; + return((uint32_t)(8*((ptr_t)bs->tail - (ptr_t)bs->start) + bs->pos - bs->initpos)); } @@ -312,7 +322,7 @@ static uint32_t __inline BitstreamLength(Bitstream * const bs) { - uint32_t len = (ptr_t) bs->tail - (ptr_t) bs->start; + uint32_t len = (uint32_t)((ptr_t)bs->tail - (ptr_t)bs->start); if (bs->pos) { uint32_t b = bs->buf; @@ -325,6 +335,10 @@ len += (bs->pos + 7) / 8; } + /* initpos is always on a byte boundary */ + if (bs->initpos) + len -= bs->initpos/8; + return len; } @@ -349,20 +363,6 @@ } } - -/* pad bitstream to the next byte boundary */ - -static void __inline -BitstreamPad(Bitstream * const bs) -{ - uint32_t remainder = bs->pos % 8; - - if (remainder) { - BitstreamForward(bs, 8 - remainder); - } -} - - /* read n bits from bitstream */ static uint32_t __inline @@ -425,4 +425,39 @@ } } +static const int stuffing_codes[8] = +{ + /* nbits stuffing code */ + 0, /* 1 0 */ + 1, /* 2 01 */ + 3, /* 3 011 */ + 7, /* 4 0111 */ + 0xf, /* 5 01111 */ + 0x1f, /* 6 011111 */ + 0x3f, /* 7 0111111 */ + 0x7f, /* 8 01111111 */ +}; + +/* pad bitstream to the next byte boundary */ + +static void __inline +BitstreamPad(Bitstream * const bs) +{ + int bits = 8 - (bs->pos % 8); + if (bits < 8) + BitstreamPutBits(bs, stuffing_codes[bits - 1], bits); +} + +/* + * pad bitstream to the next byte boundary + * alway pad: even if currently at the byte boundary + */ + +static void __inline +BitstreamPadAlways(Bitstream * const bs) +{ + int bits = 8 - (bs->pos % 8); + BitstreamPutBits(bs, stuffing_codes[bits - 1], bits); +} + #endif /* _BITSTREAM_H_ */