Audio Effects Cleanup (#1295)

* audio effects cleanup

* more cleanup

* header comments

* more docs

* cleanup

* file name fix

* swap if

* more cleanup

* move comment

* ADSR notes

* fix bss, pr review

1 files changed, 117 insertions, 0 deletions

diff --git a/include/audio/effects.h b/include/audio/effects.h
new file mode 100644
index 000000000..67741200f
--- /dev/null
+++ b/include/audio/effects.h
@@ -0,0 +1,117 @@
+#ifndef AUDIO_EFFECTS_H
+#define AUDIO_EFFECTS_H
+
+#include "PR/ultratypes.h"
+#include "unk.h"
+
+struct Note;
+struct SequencePlayer;
+
+/* Multi-Point ADSR Envelope (Attack, Decay, Sustain, Release) */
+
+typedef enum AdsrStatus {
+    /* 0 */ ADSR_STATUS_DISABLED,
+    /* 1 */ ADSR_STATUS_INITIAL,
+    /* 2 */ ADSR_STATUS_START_LOOP,
+    /* 3 */ ADSR_STATUS_LOOP,
+    /* 4 */ ADSR_STATUS_FADE,
+    /* 5 */ ADSR_STATUS_HANG,
+    /* 6 */ ADSR_STATUS_DECAY,
+    /* 7 */ ADSR_STATUS_RELEASE,
+    /* 8 */ ADSR_STATUS_SUSTAIN
+} AdsrStatus;
+
+typedef struct EnvelopePoint {
+    /* 0x0 */ s16 delay;
+    /* 0x2 */ s16 arg;
+} EnvelopePoint; // size = 0x4
+
+typedef struct AdsrSettings {
+    /* 0x0 */ u8 decayIndex; // index used to obtain adsr decay rate from adsrDecayTable
+    /* 0x1 */ u8 sustain;
+    /* 0x4 */ EnvelopePoint* envelope;
+} AdsrSettings; // size = 0x8
+
+typedef struct AdsrState {
+    union {
+        struct {
+            /* 0x00 */ u8 unused : 1;
+            /* 0x00 */ u8 hang : 1;
+            /* 0x00 */ u8 decay : 1;
+            /* 0x00 */ u8 release : 1;
+            /* 0x00 */ u8 status : 4;
+        } s;
+        /* 0x00 */ u8 asByte;
+    } action;
+    /* 0x01 */ u8 envelopeIndex;
+    /* 0x02 */ s16 delay;
+    /* 0x04 */ f32 sustain;
+    /* 0x08 */ f32 velocity;
+    /* 0x0C */ f32 fadeOutVel;
+    /* 0x10 */ f32 current;
+    /* 0x14 */ f32 target;
+    /* 0x18 */ UNK_TYPE1 pad18[4];
+    /* 0x1C */ EnvelopePoint* envelope;
+} AdsrState; // size = 0x20
+
+
+/* Vibrato */
+
+typedef struct VibratoSubStruct {
+    /* 0x0 */ u16 vibratoRateStart;
+    /* 0x2 */ u16 vibratoDepthStart;
+    /* 0x4 */ u16 vibratoRateTarget;
+    /* 0x6 */ u16 vibratoDepthTarget;
+    /* 0x8 */ u16 vibratoRateChangeDelay;
+    /* 0xA */ u16 vibratoDepthChangeDelay;
+    /* 0xC */ u16 vibratoDelay;
+} VibratoSubStruct; // size = 0xE
+
+typedef struct VibratoState {
+    /* 0x00 */ VibratoSubStruct* vibSubStruct; // Something else?
+    /* 0x04 */ u32 time; // 0x400 is 1 unit of time, 0x10000 is 1 period
+    /* 0x08 */ s16* curve;
+    /* 0x0C */ f32 depth;
+    /* 0x10 */ f32 rate;
+    /* 0x14 */ u8 active;
+    /* 0x16 */ u16 rateChangeTimer;
+    /* 0x18 */ u16 depthChangeTimer;
+    /* 0x1A */ u16 delay;
+} VibratoState; // size = 0x1C
+
+
+/* Portamento */
+
+typedef enum PortamentoMode {
+    /* 0 */ PORTAMENTO_MODE_OFF,
+    /* 1 */ PORTAMENTO_MODE_1,
+    /* 2 */ PORTAMENTO_MODE_2,
+    /* 3 */ PORTAMENTO_MODE_3,
+    /* 4 */ PORTAMENTO_MODE_4,
+    /* 5 */ PORTAMENTO_MODE_5
+} PortamentoMode;
+
+#define PORTAMENTO_IS_SPECIAL(x) ((x).mode & 0x80)
+#define PORTAMENTO_MODE(x) ((x).mode & ~0x80)
+
+// Pitch sliding by up to one octave in the positive direction. Negative
+// direction is "supported" by setting extent to be negative. The code
+// extrapolates exponentially in the wrong direction in that case, but that
+// doesn't prevent seqplayer from doing it, AFAICT.
+typedef struct Portamento {
+    /* 0x0 */ u8 mode; // bit 0x80 denotes something; the rest are an index 0-5
+    /* 0x2 */ u16 cur;
+    /* 0x4 */ u16 speed;
+    /* 0x8 */ f32 extent;
+} Portamento; // size = 0xC
+
+void AudioScript_SequencePlayerProcessSound(struct SequencePlayer* seqPlayer);
+
+void AudioEffects_InitAdsr(AdsrState* adsr, EnvelopePoint* envelope, s16* volOut);
+void AudioEffects_InitVibrato(struct Note* note);
+void AudioEffects_InitPortamento(struct Note* note);
+
+f32 AudioEffects_UpdateAdsr(AdsrState* adsr);
+void AudioEffects_UpdatePortamentoAndVibrato(struct Note* note);
+
+#endif