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/*
* 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;
}
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