mirror of
https://github.com/sehugg/8bitworkshop.git
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113 lines
2.7 KiB
C
113 lines
2.7 KiB
C
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#include <string.h>
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typedef unsigned char byte;
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typedef unsigned short word;
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typedef signed char sbyte;
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const __sfr __at (0x0) command;
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__sfr __at (0x0) dac;
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#define HALT __asm halt __endasm;
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// press "2" or higher to activate...
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typedef struct {
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word duration;
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word offset;
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word delta;
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int deltainc;
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byte* wavetable;
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byte wavemask;
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signed char lfo;
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} SoundEffect;
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const char SQUARE_LOFREQ[32] = {
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-64,-64,-64,-64,-64,-64,-64,
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-64,-64,-64,-64,-64,-64,-64,
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64,64,64,64,64,64,64,64,
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64,64,64,64,64,64,64,64
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};
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const char SQUARE_HIFREQ[32] = {
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-64,64,-64,64,-64,64,-64,64,
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-64,64,-64,64,-64,64,-64,64,
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-64,64,-64,64,-64,64,-64,64,
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-64,64,-64,64,-64,64,-64,64,
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};
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const char SINTBL[128] = {
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0, 3, 6, 9, 12, 16, 19, 22, 25, 28, 31, 34, 37, 40, 43, 46,
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49, 51, 54, 57, 60, 63, 65, 68, 71, 73, 76, 78, 81, 83, 85, 88,
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90, 92, 94, 96, 98, 100, 102, 104, 106, 107, 109, 111, 112, 113, 115, 116,
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117, 118, 120, 121, 122, 122, 123, 124, 125, 125, 126, 126, 126, 127, 127, 127,
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127, 127, 127, 127, 126, 126, 126, 125, 125, 124, 123, 122, 122, 121, 120, 118,
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117, 116, 115, 113, 112, 111, 109, 107, 106, 104, 102, 100, 98, 96, 94, 92,
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90, 88, 85, 83, 81, 78, 76, 73, 71, 68, 65, 63, 60, 57, 54, 51,
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49, 46, 43, 40, 37, 34, 31, 28, 25, 22, 19, 16, 12, 9, 6, 3,
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};
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const char TRIANGLE[32] = {
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-0x80,-0x78,-0x70,-0x68, -0x60,-0x58,-0x50,-0x48,
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-0x40,-0x38,-0x30,-0x28, -0x20,-0x18,-0x10,-0x08,
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0x00,0x08,0x10,0x18, 0x20,0x28,0x30,0x38,
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0x40,0x48,0x50,0x58, 0x60,0x68,0x70,0x78,
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};
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const char NOISE[32] = {
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0x60,0x37,0x3f,0x5c,0x16,0xca,0xc2,0xa5,0xfe,0xba,0x77,0x89,0xaa,0x77,0x13,0xd8,
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0xae,0x82,0xfd,0x22,0x9c,0x46,0xde,0x14,0x50,0xb4,0x97,0x46,0x54,0x9d,0x60,0x2b,
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};
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SoundEffect e;
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byte volume;
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const SoundEffect SOUNDS[] = {
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{ 1200, 0, 0, 1, NOISE, 0xff, 0 },
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{ 250, 0, 1000, -4, SINTBL, 0x7f, 0 },
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{ 500, 0, 1000, 2, TRIANGLE, 0x1f, 0 },
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{ 600, 0, 3000, -1, SQUARE_LOFREQ, 0x1f, 0 },
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{ 600, 0, 3000, -1, SQUARE_HIFREQ, 0x1f, 0 },
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{ 600, 0, 3000, 1, SQUARE_LOFREQ, 0x3f, 0 },
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{ 1200, 0, 0, 1, SINTBL, 0x7f, 1 },
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};
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void play();
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void main() {
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// halt on command = 0
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if (command == 0) HALT;
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// load stack pointer
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__asm
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ld sp,#0x8000
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di
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__endasm;
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// copy sound to RAM
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memcpy(&e, &SOUNDS[command-1], sizeof(e));
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// play sound
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play();
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// turn off speaker and halt
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dac = 0;
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HALT;
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}
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void sample() {
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byte val = e.wavetable[(byte)(e.offset >> 8) & e.wavemask];
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if (val <= volume) dac = val;
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e.offset += e.delta;
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}
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void play() {
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volume = 0xff;
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while (e.duration--) {
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sample();
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sample();
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sample();
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sample();
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sample();
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sample();
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sample();
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sample();
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e.delta += e.deltainc;
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e.deltainc += e.lfo;
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// taper off volume
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if (e.duration <= 0xff) volume = e.duration;
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}
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}
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