[WIP] Refactor ch3 envelope

4 files changed, 142 insertions, 75 deletions

diff --git a/Makefile b/Makefile
index 9894173..7afaf9d 100644
--- a/Makefile
+++ b/Makefile
@@ -27,7 +27,7 @@ INC_FLAGS   := $(addprefix -I,$(INC_DIRS))
 INC_FLAGS   += -I$(LIBGBA_SRC)
 
 # Output library names and executables.
-TARGET         := STEPPER-v1.8-dev-14
+TARGET         := STEPPER-v1.8-dev-15
 ELF            := $(BUILD_DIR)/$(TARGET).elf
 BIN            := $(BUILD_DIR)/$(TARGET).gba
 
diff --git a/src/globals.c b/src/globals.c
index 5063d69..c040585 100644
--- a/src/globals.c
+++ b/src/globals.c
@@ -1,15 +1,3 @@
-enum WAVES {
-    WAVE_SIN,
-    WAVE_SAW,
-    WAVE_SQUARE,
-    WAVE_MAX,
-};
-
-#define WAVE_SIZE 4
-#define WAVE_VARS 4
-
-typedef u32 Wave[WAVE_SIZE];
-
 //
 // Globals.
 //
@@ -221,9 +209,30 @@ bool redraw_scale = true;
 bool update_bpm = false;
 u8 bar_counter = 0;
 
-static Wave wave_active = {0};
-// static Wave wave_target = {0};
-// TODO: wave env status: OFF, ATTACK, DECAY
+typedef enum WaveEnv {
+    WAV_ENV_START,
+    WAV_ENV_ATTACK,
+    WAV_ENV_DECAY,
+    WAV_ENV_END,
+    WAV_ENV_OFF,
+} WaveEnv;
+
+enum WAVES {
+    WAVE_SIN,
+    WAVE_SAW,
+    WAVE_SQUARE,
+    WAVE_MAX,
+};
+
+#define WAVE_SIZE 4
+#define WAVE_VARS 4
+
+typedef u32 Wave[WAVE_SIZE];
+
+static WaveEnv wave_env = WAV_ENV_OFF;
+static const Wave *wave_target;
+static u32 wave_freq;
 static int wave_env_ticks = 0;
 static int wave_env_attack = 8;
 static int wave_env_decay = 8;
+static int wave_env_prog = 0;
diff --git a/src/main.c b/src/main.c
index a72e5e5..cea35f6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -37,6 +37,7 @@ WITH REGARD TO THIS SOFTWARE.
 //  - Study saving overhauls for bootleg cartridges.
 //  - When putting a new trigger, make sure it uses the global parameters
 //  - Bad performance when selecting patterns
+//  - Add help for attack/decay on ch3
 //
 // Low priority:
 //
diff --git a/src/sequencer.c b/src/sequencer.c
index 8863d14..4b5f34f 100644
--- a/src/sequencer.c
+++ b/src/sequencer.c
@@ -227,20 +227,33 @@ play_step(void) {
         TriggerNote *trig = &pat->ch3.notes[step_counter];
         ChannelWaveParams *params = &pat->ch3.params[step_counter];
         if (trig->active && should_play(params->prob)) {
+            Wave wave_zero = {
+                0x77777777, 0x77777777, 0x77777777, 0x77777777,
+            };
             switch (params->wave_mode) {
                 case 0: {
-                    memcpy32(wave_active, waves[params->shape_a][params->type_a], 16);
+                    wave_target = &waves[params->shape_a][params->type_a];
+                    wave_env_attack = params->wave_attack;
+                    wave_env_decay = params->wave_decay;
+                    wave_env = WAV_ENV_START;
+                    SOUND_WAVE_MODE = SOUND_WAVE_BANK_SELECT(0);
+                    memcpy32(SOUND_WAVE_RAM, wave_zero, 16);
                     SOUND_WAVE_MODE = SOUND_WAVE_BANK_SELECT(1);
-                    memcpy32(SOUND_WAVE_RAM, wave_active, 16);
+                    memcpy32(SOUND_WAVE_RAM, wave_zero, 16);
                     SOUND_WAVE_MODE = SOUND_WAVE_BANK_MODE(0)
                         | SOUND_WAVE_BANK_SELECT(0);
                 } break;
                 case 1: {
-                    memcpy32(wave_active, waves[params->shape_b][params->type_b], 16);
+                    wave_target = &waves[params->shape_b][params->type_b];
+                    wave_env_attack = params->wave_attack;
+                    wave_env_decay = params->wave_decay;
+                    wave_env = WAV_ENV_START;
                     SOUND_WAVE_MODE = SOUND_WAVE_BANK_SELECT(0);
-                    memcpy32(SOUND_WAVE_RAM, wave_active, 16);
+                    memcpy32(SOUND_WAVE_RAM, wave_zero, 16);
+                    SOUND_WAVE_MODE = SOUND_WAVE_BANK_SELECT(1);
+                    memcpy32(SOUND_WAVE_RAM, wave_zero, 16);
                     SOUND_WAVE_MODE = SOUND_WAVE_BANK_MODE(0)
-                        | SOUND_WAVE_BANK_SELECT(1);
+                        | SOUND_WAVE_BANK_SELECT(0);
                 } break;
                 case 2: {
                     SOUND_WAVE_MODE = SOUND_WAVE_BANK_SELECT(0);
@@ -249,15 +262,12 @@ play_step(void) {
                     memcpy32(SOUND_WAVE_RAM, waves[params->shape_a][params->type_a], 16);
                     SOUND_WAVE_MODE = SOUND_WAVE_BANK_MODE(1)
                         | SOUND_WAVE_BANK_SELECT(0);
+                    wave_env = WAV_ENV_OFF;
+                    SOUND_WAVE_MODE |= SOUND_WAVE_ENABLE;
+                    SOUND_WAVE_FREQ = SOUND_FREQ_RESET | sound_rates[trig->note];
                 } break;
             }
-            wave_env_ticks = 0;
-            wave_env_attack = params->wave_attack;
-            wave_env_decay = params->wave_decay;
-            SOUND_WAVE_MODE |= SOUND_WAVE_ENABLE;
-
-            SOUND_WAVE_FREQ = SOUND_FREQ_RESET
-                | sound_rates[trig->note];
+            wave_freq = sound_rates[trig->note];
             switch (params->wave_volume) {
                 case 0: { SOUND_WAVE_CTRL = SOUND_WAVE_MUTE; } break;
                 case 1: { SOUND_WAVE_CTRL = SOUND_WAVE_VOL_25; } break;
@@ -354,65 +364,112 @@ static int nseq_ticks = 0;
 IWRAM_CODE
 void
 wave_ad_tick(void) {
-    // Play a single step for A+B or no envelope.
-    if ((SOUND_WAVE_MODE & SOUND_WAVE_BANK_MODE(1)) || !wave_env_decay) {
-        if (wave_env_ticks++ == 24) {
-            SOUND_WAVE_FREQ = SOUND_FREQ_RESET;
-            SOUND_WAVE_CTRL = SOUND_WAVE_MUTE;
-        }
-        return;
-    }
+    Wave wave_active = {0};
+env_start:
+    switch (wave_env) {
+        case WAV_ENV_START: {
+            wave_env_ticks = 0;
+            wave_env_prog = 0;
+            SOUND_WAVE_MODE |= SOUND_WAVE_ENABLE;
+            SOUND_WAVE_FREQ = SOUND_FREQ_RESET | wave_freq;
 
-    if (wave_env_ticks++ < wave_env_decay) {
-        return;
-    }
-    wave_env_ticks = 0;
-
-    // Decay.
-    for (size_t j = 0; j < 4; j++) {
-        u32 next = 0;
-        for (size_t i = 0; i < 8; i++) {
-            u8 val = (wave_active[j] >> 4 * i) & 0xF;
-            // Operating in 24.8 fixed point:
-            // 0.9 = 230; 0.8 = 205; 0.75 = 192
-            int power = 205;
-            if (val < 0x7) {
-                int tmp = 0x7 - val;
-                tmp *= power;
-                tmp >>= 8;
-                val = (0x7 - tmp) & 0xf;
-            } else if (val > 0x7) {
-                int tmp = (val - 0x7);
-                tmp *= power;
-                tmp >>= 8;
-                val = tmp + 0x7;
-                if (val <= 0x7) {
-                    val = 0x7;
+            if (wave_env_attack == 0) {
+                memcpy32(wave_active, wave_target, 16);
+                memcpy32(SOUND_WAVE_RAM, wave_active, 16);
+                SOUND_WAVE_MODE ^= SOUND_WAVE_BANK_SELECT(1);
+            } else {
+                wave_env = WAV_ENV_ATTACK;
+                goto env_start;
+            }
+
+            if (wave_env_decay == 0) {
+                wave_env = WAV_ENV_OFF;
+                goto env_start;
+            } else {
+                wave_env = WAV_ENV_DECAY;
+            }
+            return;
+        } break;
+        case WAV_ENV_ATTACK: {
+            // TODO: Attack envelope
+        } break;
+        case WAV_ENV_DECAY: {
+            if (wave_env_ticks++ < wave_env_decay) {
+                return;
+            }
+            wave_env_ticks = 0;
+
+            // Decay.
+            int powers[] = {
+                // FP_NUM(1,8), 230, 205, 192, 150, 100, 50, 0
+                // 256, 128, 85, 64, 51, 43, 37, 32, 28, 0
+                // Logarithmic volume range.
+                // 256, 245, 224, 202, 177, 150, 120, 86, 47, 0,
+                 // 0.,  57., 104., 143., 177., 208., 235., 259.
+                256, 235, 208, 177, 143, 104, 57, 0
+            };
+            int power = powers[wave_env_prog];
+            if (++wave_env_prog >= 8) {
+                wave_env = WAV_ENV_END;
+            }
+            for (size_t j = 0; j < 4; j++) {
+                u32 next = 0;
+                u32 prev = (*wave_target)[j];
+                for (size_t i = 0; i < 8; i++) {
+                    u8 val = (prev >> 4 * i) & 0xF;
+                    // Operating in 24.8 fixed point:
+                    if (val < 0x7) {
+                        int tmp = 0x7 - val;
+                        tmp *= power;
+                        tmp >>= 8;
+                        val = (0x7 - tmp) & 0xf;
+                    } else if (val > 0x7) {
+                        int tmp = (val - 0x7);
+                        tmp *= power;
+                        tmp >>= 8;
+                        val = tmp + 0x7;
+                        if (val <= 0x7) {
+                            val = 0x7;
+                        }
+                    }
+                    next |= (val << 4 * i);
                 }
+                wave_active[j] = next;
             }
-            next |= (val << 4 * i);
-        }
-        wave_active[j] = next;
-    }
 
-    // DEBUG:
-    // int x = 50;
-    // int y = 50;
-    // draw_filled_rect(0 + x, 0 + y, 100 + x, 32 + y, COL_BG);
-    // draw_wave_pattern(&wave_active, 0 + x, 0 + y, 1);
+            // DEBUG:
+            // int x = 50;
+            // int y = 50;
+            // draw_filled_rect(0 + x, 0 + y, 100 + x, 32 + y, COL_BG);
+            // draw_wave_pattern(&wave_active, 0 + x, 0 + y, 1);
 
-    memcpy32(SOUND_WAVE_RAM, wave_active, 16);
-    SOUND_WAVE_MODE ^= SOUND_WAVE_BANK_SELECT(1);
+            memcpy32(SOUND_WAVE_RAM, wave_active, 16);
+            SOUND_WAVE_MODE ^= SOUND_WAVE_BANK_SELECT(1);
+        } break;
+        case WAV_ENV_OFF: {
+            if (wave_env_ticks++ == 24) {
+                SOUND_WAVE_FREQ = SOUND_FREQ_RESET;
+                SOUND_WAVE_CTRL = SOUND_WAVE_MUTE;
+                wave_env = WAV_ENV_END;
+            }
+            return;
+        } break;
+        case WAV_ENV_END: {
+            SOUND_WAVE_FREQ = SOUND_FREQ_RESET;
+            SOUND_WAVE_CTRL = SOUND_WAVE_MUTE;
+            return;
+        } break;
+    }
 }
 
 void
 sequencer_tick(void) {
-    wave_ad_tick();
     if (nseq_ticks++ == 0) {
         play_step();
     } else if (nseq_ticks == 24) {
         nseq_ticks = 0;
     }
+    wave_ad_tick();
 }
 
 void
@@ -1291,8 +1348,8 @@ set_param_selection_wave(ChannelWaveParams *params, InputHandler return_handler)
             case 4: { params->prob = CLAMP(params->prob + inc * -1, 0, PROB_NUM - 1); } break;
             case 5: { params->wave_mode = CLAMP(params->wave_mode + inc, 0, 2); } break;
             case 6: { params->wave_volume = CLAMP(params->wave_volume + inc, 0, 4); } break;
-            case 7: { params->wave_attack = CLAMP(params->wave_attack + inc, 0, 24); } break;
-            case 8: { params->wave_decay = CLAMP(params->wave_decay + inc, 0, 24); } break;
+            case 7: { params->wave_attack = CLAMP(params->wave_attack + inc, 0, 16); } break;
+            case 8: { params->wave_decay = CLAMP(params->wave_decay + inc, 0, 16); } break;
             case 9: { params->pan = CLAMP(params->pan + inc, -1, 1); } break;
         }
         redraw_params = true;