245 lines
7.6 KiB
C
245 lines
7.6 KiB
C
/*
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* Schism Tracker - a cross-platform Impulse Tracker clone
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* copyright (c) 2003-2005 Storlek <storlek@rigelseven.com>
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* copyright (c) 2005-2008 Mrs. Brisby <mrs.brisby@nimh.org>
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* copyright (c) 2009 Storlek & Mrs. Brisby
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* copyright (c) 2010-2012 Storlek
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* URL: http://schismtracker.org/
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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// slightly modified for Furnace by tildearrow
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#include "compression.h"
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#define MIN(a,b) (((a)<(b))?(a):(b))
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#define MAX(a,b) (((a)>(b))?(a):(b))
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#define CLAMP(x,xMin,xMax) (MIN(MAX((x),(xMin)),(xMax)))
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// ------------------------------------------------------------------------------------------------------------
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// IT decompression code from itsex.c (Cubic Player) and load_it.cpp (Modplug)
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// (I suppose this could be considered a merge between the two.)
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static uint32_t it_readbits(int8_t n, uint32_t *bitbuf, uint32_t *bitnum, const uint8_t **ibuf)
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{
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uint32_t value = 0;
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uint32_t i = n;
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// this could be better
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while (i--) {
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if (!*bitnum) {
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*bitbuf = *(*ibuf)++;
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*bitnum = 8;
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}
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value >>= 1;
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value |= (*bitbuf) << 31;
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(*bitbuf) >>= 1;
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(*bitnum)--;
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}
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return value >> (32 - n);
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}
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uint32_t it_decompress8(void *dest, uint32_t len, const void *file, uint32_t filelen, int it215, int channels)
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{
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const uint8_t *filebuf; // source buffer containing compressed sample data
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const uint8_t *srcbuf; // current position in source buffer
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int8_t *destpos; // position in destination buffer which will be returned
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uint16_t blklen; // length of compressed data block in samples
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uint16_t blkpos; // position in block
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uint8_t width; // actual "bit width"
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uint16_t value; // value read from file to be processed
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int8_t d1, d2; // integrator buffers (d2 for it2.15)
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int8_t v; // sample value
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uint32_t bitbuf, bitnum; // state for it_readbits
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filebuf = srcbuf = (const uint8_t *) file;
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destpos = (int8_t *) dest;
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// now unpack data till the dest buffer is full
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while (len) {
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// read a new block of compressed data and reset variables
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// block layout: word size, <size> bytes data
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if (srcbuf + 2 > filebuf + filelen
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|| srcbuf + 2 + (srcbuf[0] | (srcbuf[1] << 8)) > filebuf + filelen) {
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// truncated!
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return srcbuf - filebuf;
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}
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srcbuf += 2;
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bitbuf = bitnum = 0;
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blklen = MIN(0x8000, len);
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blkpos = 0;
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width = 9; // start with width of 9 bits
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d1 = d2 = 0; // reset integrator buffers
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// now uncompress the data block
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while (blkpos < blklen) {
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if (width > 9) {
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// illegal width, abort
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printf("Illegal bit width %d for 8-bit sample\n", width);
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return srcbuf - filebuf;
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}
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value = it_readbits(width, &bitbuf, &bitnum, &srcbuf);
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if (width < 7) {
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// method 1 (1-6 bits)
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// check for "100..."
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if (value == 1 << (width - 1)) {
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// yes!
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value = it_readbits(3, &bitbuf, &bitnum, &srcbuf) + 1; // read new width
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width = (value < width) ? value : value + 1; // and expand it
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continue; // ... next value
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}
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} else if (width < 9) {
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// method 2 (7-8 bits)
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uint8_t border = (0xFF >> (9 - width)) - 4; // lower border for width chg
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if (value > border && value <= (border + 8)) {
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value -= border; // convert width to 1-8
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width = (value < width) ? value : value + 1; // and expand it
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continue; // ... next value
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}
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} else {
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// method 3 (9 bits)
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// bit 8 set?
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if (value & 0x100) {
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width = (value + 1) & 0xff; // new width...
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continue; // ... and next value
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}
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}
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// now expand value to signed byte
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if (width < 8) {
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uint8_t shift = 8 - width;
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v = (value << shift);
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v >>= shift;
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} else {
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v = (int8_t) value;
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}
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// integrate upon the sample values
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d1 += v;
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d2 += d1;
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// .. and store it into the buffer
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*destpos = it215 ? d2 : d1;
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destpos += channels;
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blkpos++;
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}
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// now subtract block length from total length and go on
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len -= blklen;
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}
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return srcbuf - filebuf;
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}
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// Mostly the same as above.
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uint32_t it_decompress16(void *dest, uint32_t len, const void *file, uint32_t filelen, int it215, int channels)
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{
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const uint8_t *filebuf; // source buffer containing compressed sample data
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const uint8_t *srcbuf; // current position in source buffer
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int16_t *destpos; // position in destination buffer which will be returned
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uint16_t blklen; // length of compressed data block in samples
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uint16_t blkpos; // position in block
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uint8_t width; // actual "bit width"
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uint32_t value; // value read from file to be processed
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int16_t d1, d2; // integrator buffers (d2 for it2.15)
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int16_t v; // sample value
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uint32_t bitbuf, bitnum; // state for it_readbits
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filebuf = srcbuf = (const uint8_t *) file;
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destpos = (int16_t *) dest;
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// now unpack data till the dest buffer is full
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while (len) {
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// read a new block of compressed data and reset variables
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// block layout: word size, <size> bytes data
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if (srcbuf + 2 > filebuf + filelen
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|| srcbuf + 2 + (srcbuf[0] | (srcbuf[1] << 8)) > filebuf + filelen) {
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// truncated!
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return srcbuf - filebuf;
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}
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srcbuf += 2;
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bitbuf = bitnum = 0;
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blklen = MIN(0x4000, len); // 0x4000 samples => 0x8000 bytes again
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blkpos = 0;
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width = 17; // start with width of 17 bits
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d1 = d2 = 0; // reset integrator buffers
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// now uncompress the data block
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while (blkpos < blklen) {
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if (width > 17) {
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// illegal width, abort
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printf("Illegal bit width %d for 16-bit sample\n", width);
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return srcbuf - filebuf;
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}
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value = it_readbits(width, &bitbuf, &bitnum, &srcbuf);
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if (width < 7) {
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// method 1 (1-6 bits)
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// check for "100..."
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if (value == (uint32_t) 1 << (width - 1)) {
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// yes!
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value = it_readbits(4, &bitbuf, &bitnum, &srcbuf) + 1; // read new width
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width = (value < width) ? value : value + 1; // and expand it
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continue; // ... next value
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}
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} else if (width < 17) {
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// method 2 (7-16 bits)
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uint16_t border = (0xFFFF >> (17 - width)) - 8; // lower border for width chg
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if (value > border && value <= (uint32_t) (border + 16)) {
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value -= border; // convert width to 1-8
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width = (value < width) ? value : value + 1; // and expand it
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continue; // ... next value
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}
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} else {
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// method 3 (17 bits)
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// bit 16 set?
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if (value & 0x10000) {
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width = (value + 1) & 0xff; // new width...
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continue; // ... and next value
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}
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}
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// now expand value to signed word
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if (width < 16) {
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uint8_t shift = 16 - width;
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v = (value << shift);
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v >>= shift;
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} else {
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v = (int16_t) value;
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}
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// integrate upon the sample values
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d1 += v;
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d2 += d1;
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// .. and store it into the buffer
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*destpos = it215 ? d2 : d1;
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destpos += channels;
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blkpos++;
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}
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// now subtract block length from total length and go on
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len -= blklen;
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}
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return srcbuf - filebuf;
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}
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