[WIP] Full implementation of attack/decay for ch3 (bugs?)

3 files changed, 65 insertions, 25 deletions

diff --git a/Makefile b/Makefile
index 7afaf9d..d7c0b05 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-15
+TARGET         := STEPPER-v1.8-dev-16
 ELF            := $(BUILD_DIR)/$(TARGET).elf
 BIN            := $(BUILD_DIR)/$(TARGET).gba
 
diff --git a/src/main.c b/src/main.c
index cea35f6..a068bc8 100644
--- a/src/main.c
+++ b/src/main.c
@@ -28,9 +28,8 @@ WITH REGARD TO THIS SOFTWARE.
 //  + Hold L/R retriggers at short intervals?
 //    to key release to enable trigs.
 //  + Fix bug with not being able to stop the sound when synced
+//  + Add attack and decay envelope for ch3 (synced to tempo)
 //  - Fix any bugs we currently have
-//  - Add an envelope to ch3, would need to work with a timer in order to make
-//    it work I think (Can reuse the 96bpq sequencer timer for this).
 //  - Add clipboard sharing between banks.
 //  - Make sure transposing a sequence past the keyboard limit doesn't affect
 //    the sequence and can be reversed.
@@ -38,6 +37,7 @@ WITH REGARD TO THIS SOFTWARE.
 //  - When putting a new trigger, make sure it uses the global parameters
 //  - Bad performance when selecting patterns
 //  - Add help for attack/decay on ch3
+//  - Fix A+B on ch3
 //
 // Low priority:
 //
diff --git a/src/sequencer.c b/src/sequencer.c
index 4b5f34f..66f1d24 100644
--- a/src/sequencer.c
+++ b/src/sequencer.c
@@ -227,33 +227,18 @@ 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: {
                     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_zero, 16);
-                    SOUND_WAVE_MODE = SOUND_WAVE_BANK_MODE(0)
-                        | SOUND_WAVE_BANK_SELECT(0);
                 } break;
                 case 1: {
                     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_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(0);
                 } break;
                 case 2: {
                     SOUND_WAVE_MODE = SOUND_WAVE_BANK_SELECT(0);
@@ -361,21 +346,30 @@ play_step(void) {
 
 static int nseq_ticks = 0;
 
+UNROLL_LOOPS
 IWRAM_CODE
 void
 wave_ad_tick(void) {
     Wave wave_active = {0};
+    Wave wave_zero = {
+        0x77777777, 0x77777777, 0x77777777, 0x77777777,
+    };
 env_start:
     switch (wave_env) {
         case WAV_ENV_START: {
             wave_env_ticks = 0;
             wave_env_prog = 0;
+            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_zero, 16);
+            SOUND_WAVE_MODE = SOUND_WAVE_BANK_MODE(0)
+                | SOUND_WAVE_BANK_SELECT(0);
             SOUND_WAVE_MODE |= SOUND_WAVE_ENABLE;
             SOUND_WAVE_FREQ = SOUND_FREQ_RESET | wave_freq;
 
             if (wave_env_attack == 0) {
-                memcpy32(wave_active, wave_target, 16);
-                memcpy32(SOUND_WAVE_RAM, wave_active, 16);
+                memcpy32(SOUND_WAVE_RAM, wave_target, 16);
                 SOUND_WAVE_MODE ^= SOUND_WAVE_BANK_SELECT(1);
             } else {
                 wave_env = WAV_ENV_ATTACK;
@@ -391,7 +385,57 @@ env_start:
             return;
         } break;
         case WAV_ENV_ATTACK: {
-            // TODO: Attack envelope
+            if (wave_env_ticks++ < wave_env_attack) {
+                return;
+            }
+            wave_env_ticks = 0;
+
+            // Attack.
+            int powers[] = {
+                20,  57, 104, 143, 177, 208, 235, 256,
+            };
+            int power = powers[wave_env_prog];
+            if (++wave_env_prog >= 8) {
+                if (wave_env_decay == 0) {
+                    wave_env = WAV_ENV_OFF;
+                } else {
+                    wave_env_prog = 0;
+                    wave_env = WAV_ENV_DECAY;
+                }
+            }
+            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;
+            }
+
+            // 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);
         } break;
         case WAV_ENV_DECAY: {
             if (wave_env_ticks++ < wave_env_decay) {
@@ -401,11 +445,7 @@ env_start:
 
             // 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];