diff options
Diffstat (limited to 'src/libmad/bit.c')
| -rwxr-xr-x | src/libmad/bit.c | 41 |
1 files changed, 29 insertions, 12 deletions
diff --git a/src/libmad/bit.c b/src/libmad/bit.c index e7004ef2f..200e3ab77 100755 --- a/src/libmad/bit.c +++ b/src/libmad/bit.c @@ -1,5 +1,5 @@ /* - * mad - MPEG audio decoder + * libmad - MPEG audio decoder library * Copyright (C) 2000-2001 Robert Leslie * * This program is free software; you can redistribute it and/or modify @@ -16,7 +16,7 @@ * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * - * $Id: bit.c,v 1.1 2001/08/12 02:57:55 guenter Exp $ + * $Id: bit.c,v 1.2 2002/04/30 18:46:58 miguelfreitas Exp $ */ # ifdef HAVE_CONFIG_H @@ -197,22 +197,39 @@ void mad_bit_write(struct mad_bitptr *bitptr, unsigned int len, unsigned short mad_bit_crc(struct mad_bitptr bitptr, unsigned int len, unsigned short init) { - register unsigned int crc, data; + register unsigned int crc; -# if CHAR_BIT == 8 - for (crc = init; len >= 8; len -= 8) { - crc = (crc << 8) ^ - crc_table[((crc >> 8) ^ mad_bit_read(&bitptr, 8)) & 0xff]; + for (crc = init; len >= 32; len -= 32) { + register unsigned long data; + + data = mad_bit_read(&bitptr, 32); + + crc = (crc << 8) ^ crc_table[((crc >> 8) ^ (data >> 24)) & 0xff]; + crc = (crc << 8) ^ crc_table[((crc >> 8) ^ (data >> 16)) & 0xff]; + crc = (crc << 8) ^ crc_table[((crc >> 8) ^ (data >> 8)) & 0xff]; + crc = (crc << 8) ^ crc_table[((crc >> 8) ^ (data >> 0)) & 0xff]; + } + + switch (len / 8) { + case 3: crc = (crc << 8) ^ + crc_table[((crc >> 8) ^ mad_bit_read(&bitptr, 8)) & 0xff]; + case 2: crc = (crc << 8) ^ + crc_table[((crc >> 8) ^ mad_bit_read(&bitptr, 8)) & 0xff]; + case 1: crc = (crc << 8) ^ + crc_table[((crc >> 8) ^ mad_bit_read(&bitptr, 8)) & 0xff]; + + len %= 8; + + case 0: break; } -# else - crc = init; -# endif while (len--) { - data = mad_bit_read(&bitptr, 1) ^ (crc >> 15); + register unsigned int msb; + + msb = mad_bit_read(&bitptr, 1) ^ (crc >> 15); crc <<= 1; - if (data & 1) + if (msb & 1) crc ^= CRC_POLY; } |