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Diffstat (limited to 'src/fmt/compression.c')
-rw-r--r-- | src/fmt/compression.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/src/fmt/compression.c b/src/fmt/compression.c new file mode 100644 index 0000000..6df9f8e --- /dev/null +++ b/src/fmt/compression.c @@ -0,0 +1,256 @@ +/* + * Schism Tracker - a cross-platform Impulse Tracker clone + * copyright (c) 2003-2005 Storlek <storlek@rigelseven.com> + * copyright (c) 2005-2008 Mrs. Brisby <mrs.brisby@nimh.org> + * copyright (c) 2009 Storlek & Mrs. Brisby + * copyright (c) 2010-2012 Storlek + * URL: http://schismtracker.org/ + * + * This program 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 of the License, or + * (at your option) any later version. + * + * This program 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 this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#define NEED_BYTESWAP +#include "headers.h" +#include "fmt.h" + +// ------------------------------------------------------------------------------------------------------------ +// IT decompression code from itsex.c (Cubic Player) and load_it.cpp (Modplug) +// (I suppose this could be considered a merge between the two.) + +static uint32_t it_readbits(int8_t n, uint32_t *bitbuf, uint32_t *bitnum, const uint8_t **ibuf) +{ + uint32_t value = 0; + uint32_t i = n; + + // this could be better + while (i--) { + if (!*bitnum) { + *bitbuf = *(*ibuf)++; + *bitnum = 8; + } + value >>= 1; + value |= (*bitbuf) << 31; + (*bitbuf) >>= 1; + (*bitnum)--; + } + return value >> (32 - n); +} + + +uint32_t it_decompress8(void *dest, uint32_t len, const void *file, uint32_t filelen, int it215, int channels) +{ + const uint8_t *filebuf; // source buffer containing compressed sample data + const uint8_t *srcbuf; // current position in source buffer + int8_t *destpos; // position in destination buffer which will be returned + uint16_t blklen; // length of compressed data block in samples + uint16_t blkpos; // position in block + uint8_t width; // actual "bit width" + uint16_t value; // value read from file to be processed + int8_t d1, d2; // integrator buffers (d2 for it2.15) + int8_t v; // sample value + uint32_t bitbuf, bitnum; // state for it_readbits + + filebuf = srcbuf = (const uint8_t *) file; + destpos = (int8_t *) dest; + + // now unpack data till the dest buffer is full + while (len) { + // read a new block of compressed data and reset variables + // block layout: word size, <size> bytes data + if (srcbuf + 2 > filebuf + filelen + || srcbuf + 2 + (srcbuf[0] | (srcbuf[1] << 8)) > filebuf + filelen) { + // truncated! + return srcbuf - filebuf; + } + srcbuf += 2; + bitbuf = bitnum = 0; + + blklen = MIN(0x8000, len); + blkpos = 0; + + width = 9; // start with width of 9 bits + d1 = d2 = 0; // reset integrator buffers + + // now uncompress the data block + while (blkpos < blklen) { + if (width > 9) { + // illegal width, abort + printf("Illegal bit width %d for 8-bit sample\n", width); + return srcbuf - filebuf; + } + value = it_readbits(width, &bitbuf, &bitnum, &srcbuf); + + if (width < 7) { + // method 1 (1-6 bits) + // check for "100..." + if (value == 1 << (width - 1)) { + // yes! + value = it_readbits(3, &bitbuf, &bitnum, &srcbuf) + 1; // read new width + width = (value < width) ? value : value + 1; // and expand it + continue; // ... next value + } + } else if (width < 9) { + // method 2 (7-8 bits) + uint8_t border = (0xFF >> (9 - width)) - 4; // lower border for width chg + if (value > border && value <= (border + 8)) { + value -= border; // convert width to 1-8 + width = (value < width) ? value : value + 1; // and expand it + continue; // ... next value + } + } else { + // method 3 (9 bits) + // bit 8 set? + if (value & 0x100) { + width = (value + 1) & 0xff; // new width... + continue; // ... and next value + } + } + + // now expand value to signed byte + if (width < 8) { + uint8_t shift = 8 - width; + v = (value << shift); + v >>= shift; + } else { + v = (int8_t) value; + } + + // integrate upon the sample values + d1 += v; + d2 += d1; + + // .. and store it into the buffer + *destpos = it215 ? d2 : d1; + destpos += channels; + blkpos++; + } + + // now subtract block length from total length and go on + len -= blklen; + } + return srcbuf - filebuf; +} + +// Mostly the same as above. +uint32_t it_decompress16(void *dest, uint32_t len, const void *file, uint32_t filelen, int it215, int channels) +{ + const uint8_t *filebuf; // source buffer containing compressed sample data + const uint8_t *srcbuf; // current position in source buffer + int16_t *destpos; // position in destination buffer which will be returned + uint16_t blklen; // length of compressed data block in samples + uint16_t blkpos; // position in block + uint8_t width; // actual "bit width" + uint32_t value; // value read from file to be processed + int16_t d1, d2; // integrator buffers (d2 for it2.15) + int16_t v; // sample value + uint32_t bitbuf, bitnum; // state for it_readbits + + filebuf = srcbuf = (const uint8_t *) file; + destpos = (int16_t *) dest; + + // now unpack data till the dest buffer is full + while (len) { + // read a new block of compressed data and reset variables + // block layout: word size, <size> bytes data + if (srcbuf + 2 > filebuf + filelen + || srcbuf + 2 + (srcbuf[0] | (srcbuf[1] << 8)) > filebuf + filelen) { + // truncated! + return srcbuf - filebuf; + } + srcbuf += 2; + + bitbuf = bitnum = 0; + + blklen = MIN(0x4000, len); // 0x4000 samples => 0x8000 bytes again + blkpos = 0; + + width = 17; // start with width of 17 bits + d1 = d2 = 0; // reset integrator buffers + + // now uncompress the data block + while (blkpos < blklen) { + if (width > 17) { + // illegal width, abort + printf("Illegal bit width %d for 16-bit sample\n", width); + return srcbuf - filebuf; + } + value = it_readbits(width, &bitbuf, &bitnum, &srcbuf); + + if (width < 7) { + // method 1 (1-6 bits) + // check for "100..." + if (value == (uint32_t) 1 << (width - 1)) { + // yes! + value = it_readbits(4, &bitbuf, &bitnum, &srcbuf) + 1; // read new width + width = (value < width) ? value : value + 1; // and expand it + continue; // ... next value + } + } else if (width < 17) { + // method 2 (7-16 bits) + uint16_t border = (0xFFFF >> (17 - width)) - 8; // lower border for width chg + if (value > border && value <= (uint32_t) (border + 16)) { + value -= border; // convert width to 1-8 + width = (value < width) ? value : value + 1; // and expand it + continue; // ... next value + } + } else { + // method 3 (17 bits) + // bit 16 set? + if (value & 0x10000) { + width = (value + 1) & 0xff; // new width... + continue; // ... and next value + } + } + + // now expand value to signed word + if (width < 16) { + uint8_t shift = 16 - width; + v = (value << shift); + v >>= shift; + } else { + v = (int16_t) value; + } + + // integrate upon the sample values + d1 += v; + d2 += d1; + + // .. and store it into the buffer + *destpos = it215 ? d2 : d1; + destpos += channels; + blkpos++; + } + + // now subtract block length from total length and go on + len -= blklen; + } + return srcbuf - filebuf; +} + +// ------------------------------------------------------------------------------------------------------------ +// MDL sample decompression + +uint16_t mdl_read_bits(uint32_t *bitbuf, uint32_t *bitnum, uint8_t **ibuf, int8_t n) +{ + uint16_t v = (uint16_t)((*bitbuf) & ((1 << n) - 1) ); + (*bitbuf) >>= n; + (*bitnum) -= n; + if ((*bitnum) <= 24) { + (*bitbuf) |= (((uint32_t)(*(*ibuf)++)) << (*bitnum)); + (*bitnum) += 8; + } + return v; +} + |