src/oscillators: Any PCM with at least 512 samples can be a wavetable.

amy/test.py

@@ -1286,7 +1286,8 @@ class TestWavetable(AmyTest):
   """Simple exercise of the wavetable oscillator, using default wavetable."""
 
   def run(self):
-    amy.send(time=0, osc=0, wave=amy.WAVETABLE, preset=0, duty='0.25,0,0,0,0.5', bp1='0,0,800,1,100,1', bp0='50,1,50,0')
+    amy.send(time=0, osc=0, wave=amy.WAVETABLE, duty='0.25,0,0,0,0.5', bp1='0,0,800,1,100,1', bp0='50,1,50,0')
+    # preset=19,
     amy.send(time=50, note=50, vel=1)
     amy.send(time=850, vel=0)
 

src/oscillators.c

@@ -807,39 +807,52 @@ void wavetable_note_on(uint16_t osc, float freq) {
 }
 
 // Structure of waveeditonlie wavetables.
-const int CYCLES_PER_WAVETABLE = 64;
+//const int CYCLES_PER_WAVETABLE = 64;
 const int WAVETABLE_SAMPLES_PER_CYCLE = 256;
 const int WAVETABLE_LOG2_SAMPLES_PER_CYCLE = 8;
 
+#ifdef GAMMA9001
+#define PCM_WAVETABLE_BASE 19
+#else
+#define PCM_WAVETABLE_BASE 11
+#endif
+
 SAMPLE render_wavetable(SAMPLE* buf, uint16_t osc) {
+    SAMPLE max_value = 0;
     float freq = freq_of_logfreq(msynth[osc]->logfreq);
-    PHASOR step = F2P(freq / (float)AMY_SAMPLE_RATE);  // cycles per sec / samples per sec -> cycles per sample
+    PHASOR step = F2P(freq / (float)AMY_SAMPLE_RATE);
     SAMPLE amp = F2S(msynth[osc]->amp);
     SAMPLE last_amp = F2S(msynth[osc]->last_amp);
     //fprintf(stderr, "render_wavetable: time %f osc %d freq %f last_amp %f amp %f preset %d\n", amy_global.total_blocks*AMY_BLOCK_SIZE / (float)AMY_SAMPLE_RATE, osc, AMY_SAMPLE_RATE * P2F(step), S2F(last_amp), S2F(amp), synth[osc]->preset);
-    SAMPLE max_value;
-    float interp = MAX(0, MIN(CYCLES_PER_WAVETABLE - 1, (CYCLES_PER_WAVETABLE - 1) * msynth[osc]->duty));  // Don't try to interp beyond end of table.  An N-waveform table can be interpolated from 0 to (N-1-eps).
-    int table = MIN((int)floor(interp), CYCLES_PER_WAVETABLE - 2);  // always need both this wavetable and the next one.
-    interp = interp - table;  // fractional part, normally < 1.0, but == 1.0 for very end of table.
-    int wavetable_preset = AMY_IS_SET(synth[osc]->preset)
-        ? (int)synth[osc]->preset
-        : (int)pcm_wavetable_base;
-    int wavetable_samples_per_table = (pcm_wavetable_len > 0) ? (int)pcm_wavetable_len : 16384;
-    uint32_t sample_length = 0;
-    const int16_t *wavetable_sample_ram =
-        pcm_get_sample_ram_for_preset((uint16_t)wavetable_preset, &sample_length);
-    if ((wavetable_sample_ram == NULL || sample_length < (uint32_t)wavetable_samples_per_table) &&
-        wavetable_preset != (int)pcm_wavetable_base) {
-        wavetable_sample_ram = pcm_get_sample_ram_for_preset(pcm_wavetable_base, &sample_length);
-    }
-    if (wavetable_sample_ram == NULL || sample_length < (uint32_t)wavetable_samples_per_table) {
+    int16_t wavetable_preset = synth[osc]->preset;
+    if (AMY_IS_UNSET(wavetable_preset))
+        wavetable_preset = PCM_WAVETABLE_BASE;
+    uint32_t sample_length;
+    const int16_t *wavetable_samples = pcm_get_sample_ram_for_preset(wavetable_preset, &sample_length);
+    if (wavetable_samples == NULL || sample_length < (2 * WAVETABLE_SAMPLES_PER_CYCLE)) {
+        // We need at least two cycles to have something to crossfade.
         return 0;
     }
-    LUT wavetable_lut = {wavetable_sample_ram, WAVETABLE_SAMPLES_PER_CYCLE, WAVETABLE_LOG2_SAMPLES_PER_CYCLE, 0, 1.0f};
-    wavetable_lut.table += table * WAVETABLE_SAMPLES_PER_CYCLE;
+    int cycles_this_table = sample_length >> WAVETABLE_LOG2_SAMPLES_PER_CYCLE;
+    // Don't try to interp beyond end of table.  An N-waveform table can be interpolated from 0 to (N-1-eps).
+    float interp = MAX(0,
+                       MIN(cycles_this_table - 1,
+                           (cycles_this_table - 1) * msynth[osc]->duty));
+    // always need both this wavetable and the next one.
+    int cycle = MIN((int)floor(interp),
+                    cycles_this_table - 2);
+    // fractional part, normally < 1.0, but == 1.0 for very end of table.
+    interp = interp - cycle;
+    LUT wavetable_lut = {
+        wavetable_samples + cycle * WAVETABLE_SAMPLES_PER_CYCLE,
+        WAVETABLE_SAMPLES_PER_CYCLE,
+        WAVETABLE_LOG2_SAMPLES_PER_CYCLE,
+        0,  /* highest harmonic, for choosing tables in set. */
+        1.0f,  /* scale factor, for denormalizing. */
+    };
     // don't update phase in the first call to render_lut, so second call uses the same phase
-    SAMPLE interp_a = F2S(1.0f - interp);
     SAMPLE interp_b = F2S(interp);
+    SAMPLE interp_a = F2S(1.0f) - interp_b;
     // If we used last_duty, we could actually smoothly interpolate the waveshape crossfade too (except across table boundaries).
     render_lut(buf, synth[osc]->phase, step, SMULR7(last_amp, interp_a), SMULR7(amp, interp_a), &wavetable_lut, &max_value);
     // Point to next cycle.