pitch computation
This commit is contained in:
Gordon JC Pearce
parent
88ca7a5037
commit
af49dcf7b6
@ -38,6 +38,10 @@ void Chassis::initAudioPort(bool input, uint32_t index, AudioPort &port) {
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void Chassis::activate() {
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// calculate filter coefficients and stuff
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printf("called activate()\n");
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for (uint8_t i=0; i<104; i++) {
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s.pitchCV[i] = (261.63 * powf(2, (i-24) / 12.0f)) / sampleRate;
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}
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}
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void Chassis::deactivate() {
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@ -126,6 +130,15 @@ void Chassis::run(const float **, float **outputs, uint32_t frames, const MidiEv
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s.runLFO();
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for (uint32_t i = 0; i < NUM_VOICES; i++) {
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s.voice[i].calcPitch(s);
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switch(s.patchRam.switch1 & 0x03) {
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case 1: s.voice[i].omega /= 4; break;
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case 2: s.voice[i].omega /= 2;
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default: break;
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}
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//printf("voice %d note = %02x ff71 = %04x\n",i, s.voice[i].note, s.voice[i].ff71 );
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s.voice[i].gate(s);
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}
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}
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@ -28,6 +28,119 @@ bool Voice::isFree() {
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return ff10 == false;
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}
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void Voice::calcPitch(Synth &s) {
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uint32_t bc, de, ea, a;
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// 03ad
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ea = 0x1818;
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// add in tuning value from ff61, not implemented
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// 03ba
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bc = s.ff51; // computed pitch LFO
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if (s.ff4a & 0x02) {
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ea -= bc;
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} else {
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ea += bc;
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}
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// 03c6
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// add in bender from ff68
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// 03d2
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s.ff6f = ea;
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ea = ff71;
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a = note;
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// 03e3
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bc = a << 8;
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// 03e6
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a = 0; // set from porta coefficient ff7d
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if (a != 0) goto h03f5;
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// 3eb
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ea = bc;
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h03ec:
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ff71 = ea; // STEAX (DE++)
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// we're not looping so we can ignore until
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// 03ee inrw ff0f voice counter
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// 03f0 eqiw ff0f, 06
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// 03f3 jr 03e0
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goto h0407;
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h03f5:
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if (ea == bc) goto h03ec; // DNE EA, BC; JR 03EC store value
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if (!(ea > bc)) goto h0401; // DGT EA, BC; JR 0401
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ea -= a;
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if (!(ea > bc)) ea = bc;
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goto h03ec;
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h0401:
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ea += a;
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if (!(ea < bc)) ea = bc;
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goto h03ec;
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h0407:
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// this outputs the Sub Osc CV
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// ignore until
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// 0413 mviw ff0f, 0 reset voice counter
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s.ff34 = 1; // unsure what this is used for
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// 0419
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ea = ff71; // pitch + fraction per voice
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bc = s.ff6f; // tune + lfo + bend
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ea += bc;
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// 0424
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s.ff6e = ea & 0xff; // MOV A, EAL; STAW 006e
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a = ea >> 8; // mov a, EAH
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// 0428
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if (a <= 0x2f) goto h04a5; // GTI A,$2F; JRE $04A5
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if (a >= 0x97) goto h04ac; // LTI A,$97; JRE $04AC
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a -= 0x30;
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h0432:
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// printf("setting omega for note %d \n", a);
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omega = ((s.pitchCV[a + 1] - s.pitchCV[a]) * (s.ff6e / 256.0)) + s.pitchCV[a];
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// 0432 onwards calculates the address for the CV
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// table at E60 and stacks it
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// 043a onwards fetches the value from the divider
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// table and computes a linear interpolation with the next one up
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// using the fractional value stored in ff6e
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// 045a onwards decides which divider to program
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// 0471 unstacks the CV table address and calculates a linear
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// interpolation of this and the next CV value using ff6e
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// 048b onwards sends it to the correct DAC
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// 0496 onwards works out which vocie to do next and loops
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// 04a3
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goto h04d5;
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h04a5: // pitch too low
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s.ff6e = 0;
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a = 0;
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goto h0432;
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h04ac: // pitch too high
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s.ff6e = 0;
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a = 0x66;
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goto h0432;
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// 04b3 programs the dividers somehow
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// ignore until 04d5
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h04d5:
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return;
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}
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void Voice::on(uint32_t key, bool reset = 0) {
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// what's with the crazy private variables and all the gotos with crazy labels?
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// this code emulates the 78C11 code directly (probably inefficiently)
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@ -37,6 +150,8 @@ void Voice::on(uint32_t key, bool reset = 0) {
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// this current implementation doesn't reset the voice
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(void)reset;
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// printf("called with key=%d\n", note);
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ff10 = true; // note held from keyboard
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ff07 = true; // attack phase
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if (note == key) goto h0144;
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@ -57,7 +172,9 @@ h0144:
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h0149:
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// this is in the wrong place really but is the equivalent of programming the counter
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// and VCO ramp DAC
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omega = (261.63 * powf(2, (note - 60) / 12.0f)) / 48000.0f;
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// omega = (261.63 * powf(2, (note - 60) / 12.0f)) / 48000.0f;
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// printf("note, key = %d, %d\n", note, key);
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return;
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}
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void Voice::off() {
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@ -152,7 +269,7 @@ h0323:
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// 032b
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bc |= 0xff00; // initial scaling value?
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//printf("0323 ");
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// printf("0323 ");
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h032d:
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tos = bc; // push bc
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@ -178,7 +295,8 @@ h032d:
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ea = (bc & 0xff) * a; // MUL C
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d = a; // MOV D,A
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a = (ea >> 8); // MOV A,EAH
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bc &= 0xff00; bc |= a; // MOV C,A
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bc &= 0xff00;
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bc |= a; // MOV C,A
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a = d; // MOV A,D
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// 0345
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@ -203,7 +321,8 @@ h032d:
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ea = (bc & 0xff) * a; // MUL C
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d = a; // MOV D,A
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a = ea >> 8; // MOV A, EAH
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bc &= 0xff00; bc |= a; // MOV C,A
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bc &= 0xff00;
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bc |= a; // MOV C,A
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a = d; // MOV A,D
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ea = (bc >> 8) * a; // MUL B
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ea += (bc & 0xff); // EADD EA,C
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@ -216,7 +335,7 @@ h036b:
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goto h0323;
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h0370: // calculate holdoff time
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//printf("0370 ");
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// printf("0370 ");
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ea = ff56; // holdoff time
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bc = attackTable[patchRam.lfoDelay]; // stored at ff58
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// 0379
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@ -231,13 +350,13 @@ h0385:
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ff1e |= 0x02; // stop predelay flag
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h0388:
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//printf("0388 ");
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// printf("0388 ");
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ea = ff5a; // envelope speed
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// 038d
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bc = lfoDelayTable[patchRam.lfoDelay >> 4]; // delay setting divided by 8 and saved at ff6c
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//printf("---------------------------------------- %04x %04x\n", ea, bc);
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// printf("---------------------------------------- %04x %04x\n", ea, bc);
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// 0391 DADDNC EA, BC
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if ((ea + bc) > 0xffff) goto h039a;
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@ -255,7 +374,7 @@ h039a:
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goto h032d;
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h03a1:
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//printf("LFO=%04x VCF=%04x flags=%02x holdoff=%04x envelope=%04x\n", ff51, ff53, ff1e, ff56, ff5a);
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// printf("LFO=%04x VCF=%04x flags=%02x holdoff=%04x envelope=%04x\n", ff51, ff53, ff1e, ff56, ff5a);
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return;
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}
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@ -19,10 +19,11 @@
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// contains the actual sound generation code
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#include "voice.hpp"
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#include <cstdio>
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#include <math.h>
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#include <cstdio>
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static inline float poly3blep0(float t) {
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float t2 = t * t;
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return 2 * (t * t2 - 0.5f * t2 * t2);
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@ -40,7 +41,6 @@ void Voice::run(Synth &s, float *buffer, uint32_t samples) {
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// there's a resistor on the panel board to sprag the range
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float pw = s.ff4f / 32768.0f;
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float sqr = 0.175;
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float saw = (s.patchRam.switch1 & 0x10) ? 0.220 : 0;
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float sub = (s.patchRam.sub / 127.0f) * 0.275;
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@ -29,14 +29,14 @@ class Voice {
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uint8_t note = 60; // per-voice note, set to middle C at 02b1h
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void on(uint32_t key, bool reset);
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void off();
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bool isFree();
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void run(Synth &s, float *buffer, uint32_t samples);
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void gate(Synth &s);
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void calcPitch(Synth &s);
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uint16_t ff71 = 0; // stores pitch + fraction
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float omega;
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private:
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enum { ATTACK,
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@ -57,7 +57,7 @@ class Voice {
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uint16_t env;
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float phase = 0, omega = 260 / 48000.0, subosc = 1;
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float phase = 0, subosc = 1;
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// float env, target;
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float delay;
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uint8_t pulseStage = 0;
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@ -111,6 +111,7 @@ class Synth {
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// RAM from ff00h to ffffh is cleared to zero
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// this is in the startup routine at 0280h
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uint8_t ff1e = 0;
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uint8_t ff34 = 0;
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uint8_t ff4a = 0; // LFO flags
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uint16_t ff4d = 0; // LFO output value
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uint16_t ff4f = 0; // computed PWM LFO
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@ -119,6 +120,9 @@ class Synth {
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uint16_t ff56 = 0; // LFO Delay envelope
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uint16_t ff5a = 0; // LFO Delay holdoff
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uint8_t ff64 = 0; // LFO mod sens amount
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uint8_t ff6e = 0; // fractional pitch temp
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uint16_t ff6f = 0; // computed pitch amount
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//uint16_t ff71 = 0; // unsure, to do with pitch
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// okay, not the greatest, this right here
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// this struct contains the bytes that make up a Juno 106 patch in
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@ -200,6 +204,8 @@ class Synth {
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uint16_t lfoDelayTable[8] = {
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0xffff, 0x0419, 0x020c, 0x015e, 0x0100, 0x0100, 0x0100, 0x0100};
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float pitchCV[104];
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void runLFO();
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void lfoDelay();
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};
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