mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-11-22 14:33:51 +00:00
111 lines
2.2 KiB
C
111 lines
2.2 KiB
C
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#pragma opt_code_speed
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typedef unsigned char byte;
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typedef signed char sbyte;
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typedef unsigned short word;
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typedef signed short sword;
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extern byte* MUZPC; // music PC
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extern byte* MUZSP; // music SP
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extern byte PVOLAB; // channels A and B volume
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extern byte PVOLMC; // channel C volume and noise mask
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extern byte VOICES; // voices mmask
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extern byte DURAT; // note duration
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__sfr __at(0x10) hw_tonmo;
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__sfr __at(0x11) hw_tonea;
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__sfr __at(0x12) hw_toneb;
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__sfr __at(0x13) hw_tonec;
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__sfr __at(0x14) hw_vibra;
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__sfr __at(0x15) hw_volc;
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__sfr __at(0x16) hw_volab;
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__sfr __at(0x17) hw_voln;
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__sfr __at(0x18) hw_sndbx;
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extern void portOut(word portVal) __z88dk_fastcall;
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static byte NEXT(void) {
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return *MUZPC++;
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}
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static void PUSH(byte b) {
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*++MUZSP = b;
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}
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static byte POP() {
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return *MUZSP--;
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}
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static byte DECTOP() {
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return --(*MUZSP);
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}
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void music_update(void) {
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byte op = NEXT();
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if (op < 0x80) {
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DURAT = op;
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op = VOICES;
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if (op & 0x01) hw_voln = NEXT();
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if (op & 0x02) hw_vibra = NEXT();
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if (op & 0x04 && (hw_tonec = *MUZPC)) {
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hw_volc = PVOLMC;
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}
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if (op & 0x08) MUZPC++;
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if (op & 0x10) {
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if (!(hw_toneb = *MUZPC))
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op ^= 0x10;
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}
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if (op & 0x20) MUZPC++;
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if (op & 0x40) {
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if (!(hw_tonea = *MUZPC))
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op ^= 0x40;
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}
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if (op & 0x80) MUZPC++;
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hw_volab =
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((op & 0x40) ? (PVOLAB & 0x0f) : 0) |
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((op & 0x10) ? (PVOLAB & 0xf0) : 0);
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} else if (op < 0x88) {
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portOut( NEXT() | ((op-0x70)<<8) );
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} else if (op == 0x88) {
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for (byte i=0; i<8; i++)
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portOut( NEXT() | (0x17-i) );
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} else switch (op & 0xf0) {
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case 0x90:
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VOICES = NEXT();
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break;
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case 0xa0:
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PUSH(op - 0x9f);
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break;
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case 0xb0:
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PVOLAB = NEXT();
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PVOLMC = NEXT();
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break;
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case 0xc0:
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if (DECTOP()) {
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MUZPC = (byte*)*(word*)MUZPC;
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} else {
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MUZPC += 2;
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POP();
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}
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break;
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case 0xd0:
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MUZPC += op & 0xf;
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break;
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case 0xe0:
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// REST
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if (op == 0xe1) {
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hw_volab = hw_volc = 0;
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DURAT = *MUZPC++;
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} else {
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// TODO: legatto/stacatto
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}
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break;
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case 0xf0:
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hw_volab = hw_volc = 0;
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VOICES = 0;
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break;
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}
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}
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