apps/codecs/libffmpegFLAC/bitstream.h

   1 /**
   2  * @file bitstream.h
   3  * bitstream api header.
   4  */
   5
   6 #ifndef BITSTREAM_H
   7 #define BITSTREAM_H
   8
   9 #include <inttypes.h>
  10
  11 #ifndef BUILD_STANDALONE
  12   #include <config.h>
  13   #include <system.h>
  14 #else
  15   #include <stdio.h>
  16   #define IBSS_ATTR
  17   #define ICONST_ATTR
  18   #define ICODE_ATTR
  19 #endif
  20
  21 #ifndef ICODE_ATTR_FLAC
  22 #define ICODE_ATTR_FLAC ICODE_ATTR
  23 #endif
  24
  25 #ifndef IBSS_ATTR_FLAC_DECODED0
  26 #define IBSS_ATTR_FLAC_DECODED0 IBSS_ATTR
  27 #endif
  28
  29 /* Endian conversion routines for standalone compilation */
  30 #ifdef BUILD_STANDALONE
  31     #ifdef BUILD_BIGENDIAN
  32         #define betoh32(x) (x)
  33         #define letoh32(x) swap32(x)
  34     #else
  35         #define letoh32(x) (x)
  36         #define betoh32(x) swap32(x)
  37     #endif
  38
  39     /* Taken from rockbox/firmware/export/system.h */
  40
  41     static inline unsigned short swap16(unsigned short value)
  42         /*
  43           result[15..8] = value[ 7..0];
  44           result[ 7..0] = value[15..8];
  45         */
  46     {
  47         return (value >> 8) | (value << 8);
  48     }
  49
  50     static inline unsigned long swap32(unsigned long value)
  51         /*
  52           result[31..24] = value[ 7.. 0];
  53           result[23..16] = value[15.. 8];
  54           result[15.. 8] = value[23..16];
  55           result[ 7.. 0] = value[31..24];
  56         */
  57     {
  58         unsigned long hi = swap16(value >> 16);
  59         unsigned long lo = swap16(value & 0xffff);
  60         return (lo << 16) | hi;
  61     }
  62 #endif
  63
  64 /* FLAC files are big-endian */
  65 #define ALT_BITSTREAM_READER_BE
  66
  67 #define NEG_SSR32(a,s) (((int32_t)(a))>>(32-(s)))
  68 #define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
  69
  70 /* bit input */
  71 /* buffer, buffer_end and size_in_bits must be present and used by every reader */
  72 typedef struct GetBitContext {
  73     const uint8_t *buffer, *buffer_end;
  74     int index;
  75     int size_in_bits;
  76 } GetBitContext;
  77
  78 #define VLC_TYPE int16_t
  79
  80 typedef struct VLC {
  81     int bits;
  82     VLC_TYPE (*table)[2]; ///< code, bits
  83     int table_size, table_allocated;
  84 } VLC;
  85
  86 typedef struct RL_VLC_ELEM {
  87     int16_t level;
  88     int8_t len;
  89     uint8_t run;
  90 } RL_VLC_ELEM;
  91
  92 #if defined(ARCH_SPARC) || defined(ARCH_ARMV4L)
  93 #define UNALIGNED_STORES_ARE_BAD
  94 #endif
  95
  96 /* used to avoid missaligned exceptions on some archs (alpha, ...) */
  97 #if defined(ARCH_X86) || defined(ARCH_X86_64)
  98 #    define unaligned32(a) (*(const uint32_t*)(a))
  99 #else
 100 #    ifdef __GNUC__
 101 static inline uint32_t unaligned32(const void *v) {
 102     struct Unaligned {
 103         uint32_t i;
 104     } __attribute__((packed));
 105
 106     return ((const struct Unaligned *) v)->i;
 107 }
 108 #    elif defined(__DECC)
 109 static inline uint32_t unaligned32(const void *v) {
 110     return *(const __unaligned uint32_t *) v;
 111 }
 112 #    else
 113 static inline uint32_t unaligned32(const void *v) {
 114     return *(const uint32_t *) v;
 115 }
 116 #    endif
 117 #endif //!ARCH_X86
 118
 119
 120 /* Bitstream reader API docs:
 121 name
 122     abritary name which is used as prefix for the internal variables
 123
 124 gb
 125     getbitcontext
 126
 127 OPEN_READER(name, gb)
 128     loads gb into local variables
 129
 130 CLOSE_READER(name, gb)
 131     stores local vars in gb
 132
 133 UPDATE_CACHE(name, gb)
 134     refills the internal cache from the bitstream
 135     after this call at least MIN_CACHE_BITS will be available,
 136
 137 GET_CACHE(name, gb)
 138     will output the contents of the internal cache, next bit is MSB of 32 or 64 bit (FIXME 64bit)
 139
 140 SHOW_UBITS(name, gb, num)
 141     will return the next num bits
 142
 143 SHOW_SBITS(name, gb, num)
 144     will return the next num bits and do sign extension
 145
 146 SKIP_BITS(name, gb, num)
 147     will skip over the next num bits
 148     note, this is equivalent to SKIP_CACHE; SKIP_COUNTER
 149
 150 SKIP_CACHE(name, gb, num)
 151     will remove the next num bits from the cache (note SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER)
 152
 153 SKIP_COUNTER(name, gb, num)
 154     will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS)
 155
 156 LAST_SKIP_CACHE(name, gb, num)
 157     will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing
 158
 159 LAST_SKIP_BITS(name, gb, num)
 160     is equivalent to SKIP_LAST_CACHE; SKIP_COUNTER
 161
 162 for examples see get_bits, show_bits, skip_bits, get_vlc
 163 */
 164
 165 static inline int unaligned32_be(const void *v)
 166 {
 167 #ifdef CONFIG_ALIGN
 168         const uint8_t *p=v;
 169         return (((p[0]<<8) | p[1])<<16) | (p[2]<<8) | (p[3]);
 170 #else
 171         return betoh32( unaligned32(v)); //original
 172 #endif
 173 }
 174
 175 static inline int unaligned32_le(const void *v)
 176 {
 177 #ifdef CONFIG_ALIGN
 178        const uint8_t *p=v;
 179        return (((p[3]<<8) | p[2])<<16) | (p[1]<<8) | (p[0]);
 180 #else
 181        return letoh32( unaligned32(v)); //original
 182 #endif
 183 }
 184
 185 #   define MIN_CACHE_BITS 25
 186
 187 #   define OPEN_READER(name, gb)\
 188         int name##_index= (gb)->index;\
 189         int name##_cache= 0;\
 190
 191 #   define CLOSE_READER(name, gb)\
 192         (gb)->index= name##_index;\
 193
 194 # ifdef ALT_BITSTREAM_READER_LE
 195 #   define UPDATE_CACHE(name, gb)\
 196         name##_cache= unaligned32_le( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
 197
 198 #   define SKIP_CACHE(name, gb, num)\
 199         name##_cache >>= (num);
 200 # else
 201 #   define UPDATE_CACHE(name, gb)\
 202         name##_cache= unaligned32_be( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
 203
 204 #   define SKIP_CACHE(name, gb, num)\
 205         name##_cache <<= (num);
 206 # endif
 207
 208 // FIXME name?
 209 #   define SKIP_COUNTER(name, gb, num)\
 210         name##_index += (num);\
 211
 212 #   define SKIP_BITS(name, gb, num)\
 213         {\
 214             SKIP_CACHE(name, gb, num)\
 215             SKIP_COUNTER(name, gb, num)\
 216         }\
 217
 218 #   define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
 219 #   define LAST_SKIP_CACHE(name, gb, num) ;
 220
 221 # ifdef ALT_BITSTREAM_READER_LE
 222 #   define SHOW_UBITS(name, gb, num)\
 223         ((name##_cache) & (NEG_USR32(0xffffffff,num)))
 224 # else
 225 #   define SHOW_UBITS(name, gb, num)\
 226         NEG_USR32(name##_cache, num)
 227 # endif
 228
 229 #   define SHOW_SBITS(name, gb, num)\
 230         NEG_SSR32(name##_cache, num)
 231
 232 #   define GET_CACHE(name, gb)\
 233         ((uint32_t)name##_cache)
 234
 235 static inline int get_bits_count(GetBitContext *s){
 236     return s->index;
 237 }
 238
 239 static inline int get_sbits(GetBitContext *s, int n){
 240     register int tmp;
 241     OPEN_READER(re, s)
 242     UPDATE_CACHE(re, s)
 243     tmp= SHOW_SBITS(re, s, n);
 244     LAST_SKIP_BITS(re, s, n)
 245     CLOSE_READER(re, s)
 246     return tmp;
 247 }
 248
 249 /**
 250  * reads 0-17 bits.
 251  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 252  */
 253 static inline unsigned int get_bits(GetBitContext *s, int n){
 254     register int tmp;
 255     OPEN_READER(re, s)
 256     UPDATE_CACHE(re, s)
 257     tmp= SHOW_UBITS(re, s, n);
 258     LAST_SKIP_BITS(re, s, n)
 259     CLOSE_READER(re, s)
 260     return tmp;
 261 }
 262
 263 unsigned int get_bits_long(GetBitContext *s, int n) ICODE_ATTR_FLAC;
 264
 265 /**
 266  * shows 0-17 bits.
 267  * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
 268  */
 269 static inline unsigned int show_bits(GetBitContext *s, int n){
 270     register int tmp;
 271     OPEN_READER(re, s)
 272     UPDATE_CACHE(re, s)
 273     tmp= SHOW_UBITS(re, s, n);
 274 //    CLOSE_READER(re, s)
 275     return tmp;
 276 }
 277
 278 unsigned int show_bits_long(GetBitContext *s, int n) ICODE_ATTR_FLAC;
 279
 280 static inline void skip_bits(GetBitContext *s, int n){
 281  //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
 282     OPEN_READER(re, s)
 283     UPDATE_CACHE(re, s)
 284     LAST_SKIP_BITS(re, s, n)
 285     CLOSE_READER(re, s)
 286 }
 287
 288 static inline unsigned int get_bits1(GetBitContext *s){
 289     int index= s->index;
 290     uint8_t result= s->buffer[ index>>3 ];
 291 #ifdef ALT_BITSTREAM_READER_LE
 292     result>>= (index&0x07);
 293     result&= 1;
 294 #else
 295     result<<= (index&0x07);
 296     result>>= 8 - 1;
 297 #endif
 298     index++;
 299     s->index= index;
 300
 301     return result;
 302 }
 303
 304 static inline unsigned int show_bits1(GetBitContext *s){
 305     return show_bits(s, 1);
 306 }
 307
 308 static inline void skip_bits1(GetBitContext *s){
 309     skip_bits(s, 1);
 310 }
 311
 312 /**
 313  * init GetBitContext.
 314  * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
 315  * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
 316  * @param bit_size the size of the buffer in bits
 317  */
 318 static inline void init_get_bits(GetBitContext *s,
 319                    const uint8_t *buffer, int bit_size)
 320 {
 321     int buffer_size= (bit_size+7)>>3;
 322     if(buffer_size < 0 || bit_size < 0) {
 323         buffer_size = bit_size = 0;
 324         buffer = 0;
 325     }
 326
 327     s->buffer= buffer;
 328     s->size_in_bits= bit_size;
 329     s->buffer_end= buffer + buffer_size;
 330     s->index=0;
 331     {
 332         OPEN_READER(re, s)
 333         UPDATE_CACHE(re, s)
 334         UPDATE_CACHE(re, s)
 335         CLOSE_READER(re, s)
 336     }
 337 }
 338
 339 void align_get_bits(GetBitContext *s) ICODE_ATTR_FLAC;
 340
 341 #endif /* BITSTREAM_H */