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/*
* Adplug - Replayer for many OPL2/OPL3 audio file formats.
* Copyright (C) 1999 - 2003 Simon Peter, <dn.tlp@gmx.net>, et al.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* bam.cpp - Bob's Adlib Music Player, by Simon Peter <dn.tlp@gmx.net>
*
* NOTES:
* In my player, the loop counter is stored with the label. This can be
* dangerous for some situations (see below), but there shouldn't be any BAM
* files triggering this situation.
*
* From SourceForge Bug #476088:
* -----------------------------
* Using just one loop counter for each label, my player can't
* handle files that loop twice to the same label (if that's at
* all possible with BAM). Imagine the following situation:
*
* ... [*] ---- [<- *] ---- [<- *] ...
* ^ ^ ^ ^ ^ ^ ^
* | | | | | | |
* +---|----+-----|-----+-----|----+--- normal song data
* +----------|-----------|-------- label 1
* +-----------+-------- loop points to label 1
*
* both loop points loop to the same label. Storing the loop
* count with the label would cause chaos with the counter,
* when the player executes the inner jump.
* ------------------
* Not to worry. my reference implementation of BAM does not
* support the multiple loop situation you describe, and
* neither do any BAM-creation programs. Then both loops point
* to the same label, the inner loop's counter is just allowed
* to clobber the outer loop's counter. No stack is neccisary.
*/
#include <string.h>
#include "bam.h"
const unsigned short CbamPlayer::freq[] = {172,182,193,205,217,230,243,258,274,
290,307,326,345,365,387,410,435,460,489,517,547,580,614,651,1369,1389,1411,
1434,1459,1484,1513,1541,1571,1604,1638,1675,2393,2413,2435,2458,2483,2508,
2537,2565,2595,2628,2662,2699,3417,3437,3459,3482,3507,3532,3561,3589,3619,
3652,3686,3723,4441,4461,4483,4506,4531,4556,4585,4613,4643,4676,4710,4747,
5465,5485,5507,5530,5555,5580,5609,5637,5667,5700,5734,5771,6489,6509,6531,
6554,6579,6604,6633,6661,6691,6724,6758,6795,7513,7533,7555,7578,7603,7628,
7657,7685,7715,7748,7782,7819,7858,7898,7942,7988,8037,8089,8143,8191,8191,
8191,8191,8191,8191,8191,8191,8191,8191,8191,8191};
CPlayer *CbamPlayer::factory(Copl *newopl)
{
return new CbamPlayer(newopl);
}
bool CbamPlayer::load(const char *filename, const CFileProvider &fp)
{
binistream *f = fp.open(filename); if(!f) return false;
char id[4];
unsigned int i;
size = fp.filesize(f) - 4; // filesize minus header
f->readString(id, 4);
if(strncmp(id,"CBMF",4)) { fp.close(f); return false; }
song = new unsigned char [size];
for(i = 0; i < size; i++) song[i] = f->readInt(1);
fp.close(f);
rewind(0);
return true;
}
bool CbamPlayer::update()
{
unsigned char cmd,c;
if(del) {
del--;
return !songend;
}
if(pos >= size) { // EOF detection
pos = 0;
songend = true;
}
while(song[pos] < 128) {
cmd = song[pos] & 240;
c = song[pos] & 15;
switch(cmd) {
case 0: // stop song
pos = 0;
songend = true;
break;
case 16: // start note
if(c < 9) {
opl->write(0xa0 + c, freq[song[++pos]] & 255);
opl->write(0xb0 + c, (freq[song[pos]] >> 8) + 32);
} else
pos++;
pos++;
break;
case 32: // stop note
if(c < 9)
opl->write(0xb0 + c, 0);
pos++;
break;
case 48: // define instrument
if(c < 9) {
opl->write(0x20 + op_table[c],song[pos+1]);
opl->write(0x23 + op_table[c],song[pos+2]);
opl->write(0x40 + op_table[c],song[pos+3]);
opl->write(0x43 + op_table[c],song[pos+4]);
opl->write(0x60 + op_table[c],song[pos+5]);
opl->write(0x63 + op_table[c],song[pos+6]);
opl->write(0x80 + op_table[c],song[pos+7]);
opl->write(0x83 + op_table[c],song[pos+8]);
opl->write(0xe0 + op_table[c],song[pos+9]);
opl->write(0xe3 + op_table[c],song[pos+10]);
opl->write(0xc0 + c,song[pos+11]);
}
pos += 12;
break;
case 80: // set label
label[c].target = ++pos;
label[c].defined = true;
break;
case 96: // jump
if(label[c].defined)
switch(song[pos+1]) {
case 254: // infinite loop
if(label[c].defined) {
pos = label[c].target;
songend = true;
break;
}
// fall through...
case 255: // chorus
if(!chorus && label[c].defined) {
chorus = true;
gosub = pos + 2;
pos = label[c].target;
break;
}
// fall through...
case 0: // end of loop
pos += 2;
break;
default: // finite loop
if(!label[c].count) { // loop elapsed
label[c].count = 255;
pos += 2;
break;
}
if(label[c].count < 255) // loop defined
label[c].count--;
else // loop undefined
label[c].count = song[pos+1] - 1;
pos = label[c].target;
break;
}
break;
case 112: // end of chorus
if(chorus) {
pos = gosub;
chorus = false;
} else
pos++;
break;
default: // reserved command (skip)
pos++;
break;
}
}
if(song[pos] >= 128) { // wait
del = song[pos] - 127;
pos++;
}
return !songend;
}
void CbamPlayer::rewind(int subsong)
{
int i;
pos = 0; songend = false; del = 0; gosub = 0; chorus = false;
memset(label, 0, sizeof(label)); label[0].defined = true;
for(i = 0; i < 16; i++) label[i].count = 255; // 255 = undefined
opl->init(); opl->write(1,32);
}
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