removed aliasing in rect and saw oscilators

examples/curlywas/tim_ges.cwa

@@ -1,3 +1,5 @@
+import "env.memory" memory(4);
+
 fn melody(ch: i32, t: i32, T: i32) {
     let lazy riff_pos = abs(((T&31) - 16) as f32) as i32;
     let lazy shift = ((1-((T>>5)&3))%2-1) * 2;
@@ -7,7 +9,7 @@ fn melody(ch: i32, t: i32, T: i32) {
     let inline riff_note = 5514 >> (riff_pos % note_count * 4) & 15;
     let inline melody_note = shift + octave - riff_note;
 
-    ch?1 = riff_pos * 10 + 4;
+    ch?1 = riff_pos * 10 + 63;
     ch?3 = melody_note + 64;
 
     let inline arp_note = shift + ((0x85>>((t/2)%3*4)) & 15) - 1;
@@ -36,12 +38,12 @@ export fn upd() {
 
 data 80 {
     i8(
-        0, 64, 0, 128, 0, 0x90,
+        0, 80, 0, 128, 0, 0x90,
-        0, 64, 0, 128, 0, 0x4c,
+        0, 80, 0, 128, 0, 0x4c,
         5, 128, 0, 128, 0, 0x4c,
         5, 128, 0, 128, 0, 0x4c,
         0xf8, 0x85,
-        0x81, 0x81, 0, 105, 0, 80
+        0x81, 0x81, 0, 110, 0, 80
     )
 }
 

platform/src/ges.cwa

@@ -34,8 +34,9 @@ export fn gesSnd(t: i32) -> f32 {
             channelState?GesChannelState.Trigger = ctrl;
 
             if envState {
-                envVol = envVol + 8 * pow(1.5625, (15 - channelReg?4 & 15) as f32) as i32;
+                let lazy attack = channelReg?4 & 15;
-                if envVol >= 65535 {
+                envVol = envVol + 12 * pow(1.5625, (15 - attack) as f32) as i32;
+                if envVol >= 65535 | !attack {
                     envVol = 65535;
                     envState = 0;
                 }
@@ -61,25 +62,33 @@ export fn gesSnd(t: i32) -> f32 {
 
             let inline pulseWidth = channelReg?1;
             let phaseShift = (pulseWidth - 128) * 255;
+            let invPhaseInc = 1 as f32 / phaseInc as f32;
 
             i = 0;
             let wave = ctrl >> 6;
             if wave < 2 {
                 if wave {
+                    let pulsePhase1 = pulseWidth << 23;
+                    let pulsePhase2 = (511 - pulseWidth) << 23;
                     loop sawLoop {
                         let p = (phase ^ 32768) << 16;
-                        p = ((p ^ (p >> 31)) >> 15) + phaseShift;
+                        let saw = (p >> 16) - polyBlep(phase, invPhaseInc, -32767);
-                        p = (p < 0 | p > 65535) * 65535;
+                        let saw2 = select(p #>= pulsePhase1 & p #< pulsePhase2, -saw, saw);
-                        i!(GesBufferOffset + 128*4) = (phase ^ p & 65535) - 32768;
+                        let saw2 = saw2 -
+                            polyBlep((p - pulsePhase1) >> 16, invPhaseInc, -saw) -
+                            polyBlep((p - pulsePhase2) >> 16, invPhaseInc, saw);
+                        i!(GesBufferOffset + 128*4) = saw2;
                         phase = phase + phaseInc;
                         branch_if (i := i + 4) < 64*4: sawLoop;
                     }
                 }
                 else
                 {
+                    let pulsePhase = 32768 + pulseWidth * 128;
                     loop rectLoop {
-                        let p = (phase & 65535) + phaseShift;
+                        i!(GesBufferOffset + 128*4) = select((phase & 65535) < pulsePhase, -32768, 32767) -
-                        i!(GesBufferOffset + 128*4) = select(p >= 32768, -32768, 32767);
+                            polyBlep(phase, invPhaseInc, -32767) -
+                            polyBlep(phase - pulsePhase, invPhaseInc, 32767);
                         phase = phase + phaseInc;
                         branch_if (i := i + 4) < 64*4: rectLoop;
                     }
@@ -163,3 +172,9 @@ export fn gesSnd(t: i32) -> f32 {
     }
     (((t & 127) * 4)!GesBufferOffset) as f32 / 32768 as f32
 }
+
+fn polyBlep(transientPhase: i32, invPhaseInc: f32, magnitude: i32) -> i32 {
+    let lazy t = ((transientPhase << 16) >> 16) as f32 * invPhaseInc;
+    let lazy x = max(0 as f32, 1 as f32 - abs(t));
+    (f32.copysign(x * x, t) * magnitude as f32) as i32
+}

test/ges_test.cwa

@@ -0,0 +1,30 @@
+import "env.memory" memory(4);
+import "env.pow" fn pow(f32, f32) -> f32;
+import "env.sin" fn sin(f32) -> f32;
+import "env.cls" fn cls(i32);
+import "env.rectangle" fn rectangle(f32, f32, f32, f32, i32);
+
+include "../platform/src/ges.cwa"
+
+export fn snd(t: i32) -> f32 {
+    gesSnd(t)
+}
+
+export fn upd() {
+    80?0 = 32!32 / 200 & 2 | 0x41;
+    80?3 = (32!32 / 400)%7*12/7 + 40;
+    let pulse = (32!32 * 256 / 2000) & 511;
+    if pulse >= 256 {
+        pulse = 511 - pulse;
+    }
+    80?1 = pulse;
+
+    cls(0);
+    rectangle(0.0, 100.0, (pulse * 320 / 256) as f32, 16.0, 15);
+}
+
+data 80 {
+    i8(
+        0x41, 0, 0, 80, 0x70, 0
+    )
+}