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Diffstat (limited to 'ac3dec/bitstream.h')
-rw-r--r-- | ac3dec/bitstream.h | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/ac3dec/bitstream.h b/ac3dec/bitstream.h new file mode 100644 index 0000000..3351930 --- /dev/null +++ b/ac3dec/bitstream.h @@ -0,0 +1,76 @@ +/* + * bitstream.h + * + * Copyright (C) Aaron Holtzman - Dec 1999 + * + * This file is part of ac3dec, a free AC-3 audio decoder + * + * ac3dec is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * ac3dec is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GNU Make; see the file COPYING. If not, write to + * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + * + */ + +//My new and improved vego-matic endian swapping routine +//(stolen from the kernel) +#ifdef WORDS_BIGENDIAN + +# define swab32(x) (x) + +#else + +# if defined (__i386__) + +# define swab32(x) __i386_swab32(x) + static inline const uint_32 __i386_swab32(uint_32 x) + { + __asm__("bswap %0" : "=r" (x) : "0" (x)); + return x; + } + +# else + +# define swab32(x)\ +((((uint_8*)&x)[0] << 24) | (((uint_8*)&x)[1] << 16) | \ + (((uint_8*)&x)[2] << 8) | (((uint_8*)&x)[3])) + +# endif +#endif + +extern uint_32 bits_left; +extern uint_32 current_word; + +void bitstream_init(uint_8 *start); + +uint_8 bitstream_get_byte(void); + +uint_8 *bitstream_get_buffer_start(void); +void bitstream_buffer_frame(uint_32 frame_size); + +uint_32 bitstream_get_bh(uint_32 num_bits); + +static inline uint_32 +bitstream_get(uint_32 num_bits) +{ + uint_32 result; + + if(num_bits < bits_left) + { + result = (current_word << (32 - bits_left)) >> (32 - num_bits); + bits_left -= num_bits; + return result; + } + + return bitstream_get_bh(num_bits); +} + |