arm7: decompile SND_channel

2 files changed, 117 insertions, 1 deletions

diff --git a/arm7/lib/src/SND_channel.c b/arm7/lib/src/SND_channel.c
new file mode 100644
index 00000000..66acf606
--- /dev/null
+++ b/arm7/lib/src/SND_channel.c
@@ -0,0 +1,116 @@
+#include "SND_channel.h"
+
+#include "SND_lfo.h"
+
+// TODO remove this extern once we actually know where this table is
+extern u8 sSampleDataShiftTable[4];
+
+u16 CalcDecayCoeff(int vol) {
+    if (vol == 127)
+        return 0xFFFF;
+    else if (vol == 126)
+        return 0x3C00;
+    else if (vol < 50)
+        return (u16)(vol * 2 + 1);
+    else
+        return (u16)(0x1E00 / (126 - vol));
+}
+
+void ExChannelSetup(struct SNDExChannel *chn, SNDExChannelCallback callback, void *callbackUserData, int priority) {
+    chn->channelLLNext = NULL;
+    chn->callback = callback;
+    chn->callbackUserData = callbackUserData;
+    chn->length = 0;
+    chn->priority = (u8)priority;
+    chn->volume = 127;
+    chn->flags.start = FALSE;
+    chn->flags.autoSweep = TRUE;
+    chn->midiKey = 60;
+    chn->rootMidiKey = 60;
+    chn->velocity = 127;
+    chn->initPan = 0;
+    chn->userDecay = 0;
+    chn->userDecay2 = 0;
+    chn->userPitch = 0;
+    chn->userPan = 0;
+    chn->panRange = 127;
+    chn->sweepPitch = 0;
+    chn->sweepLength = 0;
+    chn->sweepCounter = 0;
+
+    SND_SetExChannelAttack(chn, 127);
+    SND_SetExChannelDecay(chn, 127);
+    SND_SetExChannelSustain(chn, 127);
+    SND_SetExChannelRelease(chn, 127);
+    SND_InitLfoParam(&chn->lfo.param);
+}
+
+void ExChannelStart(struct SNDExChannel *chn, int length) {
+    chn->envAttenuation = -92544;
+    chn->envStatus = 0;
+    chn->length = length;
+    SND_StartLfo(&chn->lfo);
+    chn->flags.start = TRUE;
+    chn->flags.active = TRUE;
+}
+
+int ExChannelVolumeCmp(struct SNDExChannel *chn_a, struct SNDExChannel *chn_b) {
+    int vol_a = chn_a->volume & 0xFF;
+    int vol_b = chn_b->volume & 0xFF;
+
+    vol_a <<= 4;
+    vol_b <<= 4;
+
+    vol_a >>= sSampleDataShiftTable[chn_a->volume >> 8];
+    vol_b >>= sSampleDataShiftTable[chn_b->volume >> 8];
+
+    if (vol_a != vol_b) {
+        if (vol_a < vol_b)
+            return 1;
+        else
+            return -1;
+    }
+    return 0;
+}
+
+int ExChannelSweepUpdate(struct SNDExChannel *chn, BOOL step) {
+    s64 result;
+
+    if (chn->sweepPitch == 0) {
+        result = 0;
+    } else if (chn->sweepCounter >= chn->sweepLength) {
+        result = 0;
+    } else {
+        result = (s64)chn->sweepPitch * (chn->sweepLength - chn->sweepCounter) / chn->sweepLength;
+
+        if (step && chn->flags.autoSweep)
+            chn->sweepCounter++;
+    }
+
+    return (int)result;
+}
+
+int ExChannelLfoUpdate(struct SNDExChannel *chn, BOOL step) {
+    s64 result = SND_GetLfoValue(&chn->lfo);
+
+    if (result != 0) {
+        switch (chn->lfo.param.target) {
+        case SND_LFO_VOLUME:
+            result *= 60;
+            break;
+        case SND_LFO_PITCH:
+            result <<= 6;
+            break;
+        case SND_LFO_PAN:
+            result <<= 6;
+            break;
+        }
+        result >>= 14;
+    }
+
+    if (step) {
+        SND_UpdateLfo(&chn->lfo);
+    }
+
+    return (int)result;
+}
diff --git a/arm7/lib/src/SND_lfo.c b/arm7/lib/src/SND_lfo.c
index eca98197..262c6d27 100644
--- a/arm7/lib/src/SND_lfo.c
+++ b/arm7/lib/src/SND_lfo.c
@@ -32,7 +32,7 @@ void SND_UpdateLfo(struct SNDLfo *lfo) {
     }
 }
 
-s32 SND_GetLfoValue(struct SNDLfo *lfo) {
+int SND_GetLfoValue(struct SNDLfo *lfo) {
     if (lfo->param.depth == 0) {
         return 0;
     } else if (lfo->delayCounter < lfo->param.delay) {