From d4c386f61c360192af0c0298d018bd2cce85d036 Mon Sep 17 00:00:00 2001
From: grm <grm@eyesin.space>
Date: Sat, 16 Aug 2025 12:12:33 +0300
Subject: Some initial docu and small ui updates

---
 src/osc.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

(limited to 'src/osc.c')

diff --git a/src/osc.c b/src/osc.c
index 28e35b4..70e7c32 100644
--- a/src/osc.c
+++ b/src/osc.c
@@ -18,6 +18,12 @@ osc_interpolate(float offset, float start, float end) {
   return m * x + b;
 }
 
+/**
+ * Takes a floating-point position (offset) in the oscillator/buffer.
+ * Wraps it so it stays between osc->start and osc->len - 1 (cyclically).
+ * Converts it to an integer index.
+ * Returns the next index, wrapping back to osc->start if it reaches the end.
+ */
 int
 osc_next_index(osc_t * osc, float offset)
 {
@@ -27,7 +33,18 @@ osc_next_index(osc_t * osc, float offset)
   int current_index = (int)offset;
   return current_index + 1 >= osc->len ? osc->start : current_index + 1;
 }
+// TODO same from AI: check it
+/* int */
+/* osc_next_index(osc_t *osc, float offset) { */
+/*     float range = osc->len - osc->start; */
 
+/*     // Wrap offset into the [start, len) range */
+/*     offset = osc->start + fmodf(offset - osc->start + range, range); */
+
+/*     // Get integer index and advance */
+/*     int next = (int)offset + 1; */
+/*     return (next >= osc->len) ? osc->start : next; */
+/* } */
 
 float
 osc_next_offset(osc_t * osc, float f, float offset)
@@ -52,6 +69,40 @@ osc_next_offset(osc_t * osc, float f, float offset)
   return offset;
 }
 
+/* static inline float wrap_offset(float x, float start, float len) { */
+/*     float range = len - start; */
+/*     x -= start; */
+/*     x -= range * floorf(x / range); // efficient wrap to [0, range) */
+/*     return start + x; */
+/* } */
+
+/* float osc_next_offset(osc_t * osc, float f, float offset) */
+/* { */
+/*     // Wrap once at the start */
+/*     if (offset < osc->start || offset >= osc->len) { */
+/*         offset = wrap_offset(offset, osc->start, osc->len); */
+/*     } */
+
+/*     if (osc->type == SAMPLE) { */
+/*         // Precomputed constant for (16.35160 * 2^(2 + 5/12)) */
+/*         // = base frequency for A2 mapping */
+/*         #define BASE_A2_FACTOR  220.00000f */
+/*         f /= BASE_A2_FACTOR; */
+/*     } */
+
+/*     // Precompute conversion factor */
+/*     float step = f * ((osc->len - osc->start) / (float)SAMPLE_RATE); */
+
+/*     offset += step; */
+
+/*     // Single wrap without fmodf (branchless for most cases) */
+/*     if (offset >= osc->len) { */
+/*         offset -= osc->len; */
+/*     } */
+
+/*     return offset; */
+/* } */
+
 int
 osc_load_wav(osc_t * osc, const char * path)
 {
-- 
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