From 1a18af8baf2bc0d02fbc1f6d0e21efbbee4c17dc Mon Sep 17 00:00:00 2001
From: veclav talica <veclavtalica@protonmal.com>
Date: Thu, 25 May 2023 19:05:34 +0500
Subject: [PATCH] fixes to oscillators article

---
 articles/oscillators/page.mmd | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/articles/oscillators/page.mmd b/articles/oscillators/page.mmd
index db17af3..5e46542 100644
--- a/articles/oscillators/page.mmd
+++ b/articles/oscillators/page.mmd
@@ -14,6 +14,8 @@ Inspirations are taken from [musicdsp](https://www.musicdsp.org/).
 
 ### Sine/Cosine ###
 
+![](/articles/oscillators/sine.gif)
+
 ```c
 /* Intended to be executed offline with values then embedded in the binary.
  * By having usage of glibc sin and cos functions strictly offline it's easier to have it freestanding
@@ -38,6 +40,8 @@ void pump_sinewave(struct sinewave *wave) {
 
 ### Square ###
 
+![](/articles/oscillators/sqrt.gif)
+
 ```c
 /* Implemented over sinewave */
 struct sqrtwave {
@@ -49,7 +53,9 @@ struct sqrtwave {
 } init_sqrtwave(float frequency, float phase, float amplitude) {
   struct sqrtwave r;
   r.w = init_sinewave(frequency, phase, 1.f);
-  r.v.f = amplitude;
+  v.f = r.w.s;
+  a.f = amplitude;
+  r.v.u = (a.u & 0x7fffffff) | (v.u & 0x80000000);
   return r;
 }
 
@@ -68,6 +74,8 @@ void pump_sqrtwave(struct sqrtwave *wave) {
 
 ### Saw ###
 
+![](/articles/oscillators/sawt.gif)
+
 ```c
 struct sawtwave {
   float v, a, i;
@@ -75,7 +83,7 @@ struct sawtwave {
   struct sawtwave r;
   r.v = sinf(phase) * amplitude;
   r.a = amplitude;
-  r.i = frequency / AUDIO_FRAME_RATE * amplitude;
+  r.i = 2.f * frequency / AUDIO_FRAME_RATE * amplitude;
   return r;
 }
 
@@ -83,7 +91,11 @@ struct sawtwave {
 void pump_sawtwave(struct sawtwave *wave) {
   wave->v += wave->i;
   if (wave->v > wave->a)
-    wave->v -= wave->a;
+    wave->v -= wave->a * 2.f;
 }
 
 ```
+
+### Edits ###
+- Fixed initial value based on phase in sqrtwave, proper range for sawtwave.
+- Added waveform gifs.