1 files changed, 39 insertions, 0 deletions
diff --git a/arm7/lib/src/SND_exChannel.c b/arm7/lib/src/SND_exChannel.c
index 54c5a3c4..6081150f 100644
--- a/arm7/lib/src/SND_exChannel.c
+++ b/arm7/lib/src/SND_exChannel.c
@@ -429,3 +429,42 @@ void SND_InvalidateWave(const void *start, const void *end) {
         }
     }
 }
+
+void SND_InitLfoParam(struct SNDLfoParam *lfoParam) {
+    lfoParam->target = SND_LFO_PITCH;
+    lfoParam->depth = 0;
+    lfoParam->range = 1;
+    lfoParam->speed = 16;
+    lfoParam->delay = 0;
+}
+
+void SND_StartLfo(struct SNDLfo *lfo) {
+    lfo->counter = 0;
+    lfo->delayCounter = 0;
+}
+
+void SND_UpdateLfo(struct SNDLfo *lfo) {
+    if (lfo->delayCounter < lfo->param.delay) {
+        lfo->delayCounter++;
+    } else {
+        u32 tmp = lfo->counter;
+        tmp += lfo->param.speed << 6;
+        tmp >>= 8;
+        while (tmp >= 0x80) {
+            tmp -= 0x80;
+        }
+        lfo->counter += lfo->param.speed << 6;
+        lfo->counter &= 0xFF;
+        lfo->counter |= tmp << 8;
+    }
+}
+
+int SND_GetLfoValue(struct SNDLfo *lfo) {
+    if (lfo->param.depth == 0) {
+        return 0;
+    } else if (lfo->delayCounter < lfo->param.delay) {
+        return 0;
+    } else {
+        return SND_SinIdx((s32)((u32)lfo->counter >> 8)) * lfo->param.depth * lfo->param.range;
+    }
+}