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AGI: reverse stereo for Apple IIgs + cleanup

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According to Apple IIgs emulator and recorded music on Apple IIgs,
it seems that stereo was reversed. Melody in games seems to be
playing on left channel and not on the right one.
This commit is contained in:
Martin Kiewitz 2016-01-19 03:19:13 +01:00
parent d7420c9128
commit 05fb12eb63
2 changed files with 20 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
engines/agi/sound_2gs.cpp
View File

@ -206,16 +206,16 @@ uint SoundGen2GS::generateOutput() {
// Take envelope and MIDI volume information into account.
// Also amplify.
s0 *= vol * g->vel / 127 * 80 / 256;
s1 *= vol * g->vel / 127 * 80 / 256;
s0 *= vol * g->velocity / 127 * 80 / 256;
s1 *= vol * g->velocity / 127 * 80 / 256;
// Select output channel.
if (g->osc[0].chn)
if (g->osc[0].rightChannel)
outl += s0;
else
outr += s0;
if (g->osc[1].chn)
if (g->osc[1].rightChannel)
outl += s1;
else
outr += s1;
@ -361,7 +361,7 @@ void SoundGen2GS::advanceMidiPlayer() {
void SoundGen2GS::midiNoteOff(int channel, int note, int velocity) {
// Release keys within the given MIDI channel
for (int i = 0; i < MAX_GENERATORS; i++) {
if (_generators[i].chn == channel && _generators[i].key == note)
if (_generators[i].channel == channel && _generators[i].key == note)
_generators[i].seg = _generators[i].ins->seg;
}
}
@ -384,8 +384,8 @@ void SoundGen2GS::midiNoteOn(int channel, int note, int velocity) {
velocity = 127;
g->key = note;
g->vel = velocity * _channels[channel].getVolume() / 127;
g->chn = channel;
g->velocity = velocity * _channels[channel].getVolume() / 127;
g->channel = channel;
// Instruments can define different samples to be used based on
// what the key is. Find the correct samples for our key.
@ -404,7 +404,7 @@ void SoundGen2GS::midiNoteOn(int channel, int note, int velocity) {
g->osc[0].halt = i->wave[0][wa].halt;
g->osc[0].loop = i->wave[0][wa].loop;
g->osc[0].swap = i->wave[0][wa].swap;
g->osc[0].chn = i->wave[0][wa].chn;
g->osc[0].rightChannel = i->wave[0][wa].rightChannel;
g->osc[1].base = i->base + i->wave[1][wb].offset;
g->osc[1].size = i->wave[1][wb].size;
@ -413,7 +413,7 @@ void SoundGen2GS::midiNoteOn(int channel, int note, int velocity) {
g->osc[1].halt = i->wave[1][wb].halt;
g->osc[1].loop = i->wave[1][wb].loop;
g->osc[1].swap = i->wave[1][wb].swap;
g->osc[1].chn = i->wave[1][wb].chn;
g->osc[1].rightChannel = i->wave[1][wb].rightChannel;
g->seg = 0;
g->a = 0;
@ -551,7 +551,12 @@ bool IIgsInstrumentHeader::read(Common::SeekableReadStream &stream, bool ignoreA
wave[i][k].halt = b & 0x1; // Bit 0 = HALT
wave[i][k].loop = !(b & 0x2); // Bit 1 =!LOOP
wave[i][k].swap = (b & 0x6) == 0x6; // Bit 1&2 = SWAP
wave[i][k].chn = (b >> 4) > 0; // Output channel (left or right)
// channels seem to be reversed, verified with emulator + captured apple IIgs music
if (b >> 4) {
wave[i][k].rightChannel = false; // Bit 4 set = left channel
} else {
wave[i][k].rightChannel = true; // Bit 4 not set = right channel
}
}
}

10
engines/agi/sound_2gs.h
View File

@ -85,7 +85,7 @@ struct IIgsInstrumentHeader {
bool halt; ///< Oscillator halted?
bool loop; ///< Loop mode?
bool swap; ///< Swap mode?
bool chn; ///< Output channel (left / right)
bool rightChannel; ///< Output channel (left / right)
int16 tune; ///< Fine tune in semitones (8.8 fixed point)
} wave[2][MAX_OSCILLATOR_WAVES];
@ -122,7 +122,7 @@ struct IIgsSampleHeader {
class IIgsGenerator {
public:
IIgsGenerator() : ins(NULL), key(-1), chn(-1) {
IIgsGenerator() : ins(NULL), key(-1), channel(-1) {
memset(&osc, 0, sizeof(osc));
seg = 0;
a = 0;
@ -130,8 +130,8 @@ public:
const IIgsInstrumentHeader *ins; ///< Currently used instrument
int key; ///< MIDI key
int vel; ///< MIDI velocity (& channel volume)
int chn; ///< MIDI channel
int velocity; ///< MIDI velocity (& channel volume)
int channel; ///< MIDI channel
struct {
int8 *base; ///< Sample base pointer
uint size; ///< Sample size
@ -140,7 +140,7 @@ public:
bool halt; ///< Is oscillator halted?
bool loop; ///< Is looping enabled?
bool swap; ///< Is swapping enabled?
bool chn; ///< Output channel (left / right)
bool rightChannel; ///< Output channel (left / right)
} osc[2];
int seg; ///< Current envelope segment
frac_t a; ///< Current envelope amplitude