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AGOS: Proper implementation of the Simon 1 demo aka Accolade MIDI parser.
This is based on the Elvira 1 demo.
This commit is contained in:
Johannes Schickel
parent
7173dbfd35
commit
f705a9b286
@ -31,20 +31,22 @@ namespace AGOS {
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/**
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* Simon 1 Demo version of MidiParser.
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*
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* This parser is the result of eyeballing the one MUS file that's included
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* with simon1demo. So there might be some things missing. I've tried to notate
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* question-mark areas where they occur.
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*/
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class MidiParser_S1D : public MidiParser {
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protected:
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private:
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byte *_data;
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bool _no_delta;
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struct Loop {
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uint16 timer;
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byte *start, *end;
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} _loops[16];
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uint32 readVLQ2(byte *&data);
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void chainEvent(EventInfo &info);
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protected:
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void parseNextEvent(EventInfo &info);
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void resetTracking();
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uint32 readVLQ2(byte * &data);
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public:
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MidiParser_S1D() : _data(0), _no_delta(false) {}
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@ -52,145 +54,128 @@ public:
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bool loadMusic(byte *data, uint32 size);
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};
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uint32 MidiParser_S1D::readVLQ2(byte *&data) {
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uint32 delta = 0;
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// The VLQs for simon1demo seem to be
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// in Little Endian format.
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uint32 MidiParser_S1D::readVLQ2(byte * &data) {
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byte str;
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uint32 value = 0;
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int i;
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for (i = 0; i < 4; ++i) {
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str = data[0];
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++data;
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value |= (str & 0x7F) << (i * 7);
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if (!(str & 0x80))
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break;
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// LE format VLQ, which is 2 bytes long at max.
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delta = *data++;
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if (delta & 0x80) {
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delta &= 0x7F;
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delta |= *data++ << 7;
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}
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return value;
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return delta;
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}
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void MidiParser_S1D::chainEvent(EventInfo &info) {
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// When we chain an event, we add up the old delta.
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uint32 delta = info.delta;
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parseNextEvent(info);
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info.delta += delta;
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}
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void MidiParser_S1D::parseNextEvent(EventInfo &info) {
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info.start = _position._play_pos;
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info.length = 0;
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info.delta = _no_delta ? 0 : readVLQ2(_position._play_pos);
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_no_delta = false;
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info.event = *(_position._play_pos++);
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if (info.command() < 0x8) {
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info.event = *_position._play_pos++;
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if (!(info.event & 0x80)) {
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_no_delta = true;
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info.event += 0x80;
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info.event |= 0x80;
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}
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switch (info.command()) {
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case 0x8:
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info.basic.param1 = *(_position._play_pos++);
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info.basic.param2 = 0;
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info.length = 0;
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break;
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case 0x9:
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info.basic.param1 = *(_position._play_pos++);
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info.basic.param2 = *(_position._play_pos++); // I'm ASSUMING this byte is velocity!
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info.length = 0;
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break;
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case 0xA:
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case 0xB:
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// I'm not sure what these are meant to do, or what the
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// parameter is. Elvira 1 needs them, though, and who am I to
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// argue with her?
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info.basic.param1 = *(_position._play_pos++);
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info.basic.param2 = 0;
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break;
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case 0xC:
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info.basic.param1 = *(_position._play_pos++);
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info.basic.param2 = 0;
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++_position._play_pos; // I have NO IDEA what the second byte is for.
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break;
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case 0xD:
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// Triggered by MOD0/MOD1/MOD2/MOD3/MOD4/MOD6/MOD7/MOD8/MOD9 in Elvira 2
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// Triggered by MOD0/MOD2/MOD3/MOD5/MOD6/MOD7/MOD8/MOD9/MOD10/MOD12/MOD14/MOD15/MOD20 in Waxworks
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break;
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case 0xE:
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// Triggered by MOD9 in Elvira 1
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// Triggered by MOD3/MOD5 in Elvira 2
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// Triggered by MOD3/MOD7/MOD8/MOD13 in Waxworks
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break;
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case 0xF:
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switch (info.event & 0x0F) {
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case 0x0:
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// Trigged by MOD2/MOD6/MOD15 in Waxworks
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// Pure guesswork
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info.ext.type = *(_position._play_pos++);
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info.length = readVLQ(_position._play_pos);
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info.ext.data = _position._play_pos;
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break;
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case 0x3: // Not sure, Song Select?
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// Trigged by MOD1/MOD7/MOD10 in Elvira 1
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info.basic.param1 = *(_position._play_pos++);
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if (info.event == 0xFC) {
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// This means End of Track.
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// Rewrite in SMF (MIDI transmission) form.
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info.event = 0xFF;
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info.ext.type = 0x2F;
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} else {
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switch (info.command()) {
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case 0x8: // note off
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info.basic.param1 = *_position._play_pos++;
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info.basic.param2 = 0;
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break;
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case 0x4:
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// Trigged by MOD8 in Elvira 1
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case 0x9: // note on
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info.basic.param1 = *_position._play_pos++;
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info.basic.param2 = *_position._play_pos++;
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break;
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case 0x7:
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// Trigged by MOD6 in Elvira 2
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// Trigged by MOD5 in Waxworks
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case 0xA: { // loop control
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// In case the stop mode(?) is set to 0x80 this will stop the
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// track over here.
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const int16 loopIterations = int8(*_position._play_pos++);
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if (!loopIterations) {
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_loops[info.channel()].start = _position._play_pos;
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} else {
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if (!_loops[info.channel()].timer) {
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if (_loops[info.channel()].start) {
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_loops[info.channel()].timer = uint16(loopIterations);
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_loops[info.channel()].end = _position._play_pos;
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// Go to the start of the loop
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_position._play_pos = _loops[info.channel()].start;
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}
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} else {
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if (_loops[info.channel()].timer)
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_position._play_pos = _loops[info.channel()].start;
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--_loops[info.channel()].timer;
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}
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}
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// We need to read the next midi event here. Since we can not
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// safely pass this event to the MIDI event processing.
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chainEvent(info);
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} break;
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case 0xB: // auto stop marker(?)
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// In case the stop mode(?) is set to 0x80 this will stop the
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// track.
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// We need to read the next midi event here. Since we can not
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// safely pass this event to the MIDI event processing.
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chainEvent(info);
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break;
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case 0x8: // Not sure, ?
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// Trigged by MOD19 in Waxworks
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info.basic.param1 = info.basic.param2 = 0;
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case 0xC: // program change
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info.basic.param1 = *_position._play_pos++;
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info.basic.param2 = 0;
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break;
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case 0xA:
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// Trigged by MOD5 in Elvira 2
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break;
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case 0xD: // jump to loop end
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if (_loops[info.channel()].end)
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_position._play_pos = _loops[info.channel()].end;
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case 0xC:
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// This means End of Track.
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// Rewrite in SMF (MIDI transmission) form.
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info.event = 0xFF;
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info.ext.type = 0x2F;
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info.length = 0;
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break;
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case 0xF: // Not sure, META event?
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// Trigged by MOD8/MOD9/MOD11/MOD12/MOD13 in Waxworks
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info.ext.type = *(_position._play_pos++);
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info.length = readVLQ(_position._play_pos);
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info.ext.data = _position._play_pos;
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_position._play_pos += info.length;
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// We need to read the next midi event here. Since we can not
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// safely pass this event to the MIDI event processing.
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chainEvent(info);
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break;
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default:
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error("MidiParser_S1D: Unexpected type 0x%02X found", (int) info.event);
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// The original called some other function from here, which seems
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// not to be MIDI related.
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warning("MidiParser_S1D: default case %d", info.channel());
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// We need to read the next midi event here. Since we can not
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// safely pass this event to the MIDI event processing.
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chainEvent(info);
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break;
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}
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break;
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default:
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error("MidiParser_S1D: Unexpected event 0x%02X found", (int) info.command());
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break;
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}
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}
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bool MidiParser_S1D::loadMusic(byte *data, uint32 size) {
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unloadMusic();
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// The original actually just ignores the first two bytes.
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byte *pos = data;
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if (*(pos++) != 0xFC)
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debug(1, "Expected 0xFC header but found 0x%02X instead", (int) *pos);
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// The next 3 bytes MIGHT be tempo, but we skip them and use the default.
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// setTempo (*(pos++) | (*(pos++) << 8) | (*(pos++) << 16));
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pos += 3;
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pos += 1;
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// And now we're at the actual data. Only one track.
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_num_tracks = 1;
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@ -208,7 +193,9 @@ bool MidiParser_S1D::loadMusic(byte *data, uint32 size) {
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void MidiParser_S1D::resetTracking() {
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MidiParser::resetTracking();
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_no_delta = false;
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// The first event never contains any delta.
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_no_delta = true;
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memset(_loops, 0, sizeof(_loops));
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}
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MidiParser *MidiParser_createS1D() { return new MidiParser_S1D; }
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