From bdd8c21fcfff8041ea94a972903ce42e58c2a5c2 Mon Sep 17 00:00:00 2001
From: ozpv <39195175+ozpv@users.noreply.github.com>
Date: Sat, 29 Aug 2026 23:04:49 -0500
Subject: add retain

---
 Core/Inc/Effects/retain.h  | 34 ++++++++++++++++++++++++++++++++++
 Core/Inc/Effects/ringmod.h |  9 ++++++++-
 Core/Inc/cs4272.h          | 21 ++++++++++++++++-----
 3 files changed, 58 insertions(+), 6 deletions(-)
 create mode 100755 Core/Inc/Effects/retain.h

(limited to 'Core/Inc')

diff --git a/Core/Inc/Effects/retain.h b/Core/Inc/Effects/retain.h
new file mode 100755
index 0000000..4700493
--- /dev/null
+++ b/Core/Inc/Effects/retain.h
@@ -0,0 +1,34 @@
+/*
+ * retain.h
+ *
+ *  Created on: Aug 23, 2026
+ *      Author: ozpv
+ */
+
+#ifndef INC_EFFECTS_RETAIN_H_
+#define INC_EFFECTS_RETAIN_H_
+
+#include <stddef.h>
+#include <stdint.h>
+#include "cs4272.h"
+
+/* must be a power of two
+   higher values give better frequency resolution
+   and must be paired with a higher BUFFER_SIZE */
+#define WINDOW_SIZE 4096
+/* change based on necessary overlap */
+#define HOP_SIZE (WINDOW_SIZE / 4)
+#define OVERLAP_SIZE (WINDOW_SIZE - HOP_SIZE)
+#define NUM_OVERLAPS (WINDOW_SIZE / HOP_SIZE)
+#define COMPLEX_BIN_COUNT (WINDOW_SIZE / 2 - 1)
+
+void retain_init(void);
+void retain(
+    const int32_t *samples_in,
+    int32_t *samples_out,
+    const size_t range_min,
+    const size_t range_max,
+    const enum Channel channel
+);
+
+#endif /* INC_EFFECTS_RETAIN_H_ */
diff --git a/Core/Inc/Effects/ringmod.h b/Core/Inc/Effects/ringmod.h
index 516ca6c..766fad4 100755
--- a/Core/Inc/Effects/ringmod.h
+++ b/Core/Inc/Effects/ringmod.h
@@ -20,6 +20,13 @@ typedef struct RingModParams {
     bool square_lfo;
 } RingModParams;
 
-void ringmod(float *samples, const size_t range_min, const size_t range_max, const struct RingModParams *params);
+void ringmod(
+    const struct RingModParams *params,
+    const int32_t *samples_in,
+    int32_t *samples_out,
+    const size_t range_min,
+    const size_t range_max,
+    const enum Channel channel
+);
 
 #endif /* INC_EFFECTS_RINGMOD_H_ */
diff --git a/Core/Inc/cs4272.h b/Core/Inc/cs4272.h
index 423b7c0..4e22263 100755
--- a/Core/Inc/cs4272.h
+++ b/Core/Inc/cs4272.h
@@ -26,16 +26,27 @@
 #define CS4272_I2C_ADDR (0b0010000 << 1)
 
 #define SAMPLE_RATE 48000
-#define BUFFER_SIZE 512
+#define BUFFER_SIZE 1024
 
-extern volatile int32_t rx_buffer[BUFFER_SIZE];
-extern volatile int32_t tx_buffer[BUFFER_SIZE];
-extern volatile float samples[BUFFER_SIZE];
+typedef enum Channel {
+    LEFT = 0,
+    RIGHT = 1,
+    MONO = 0,
+} Channel;
+
+extern int32_t rx_buffer[BUFFER_SIZE];
+extern int32_t tx_buffer[BUFFER_SIZE];
 
 extern const uint8_t CS4272_CONFIG[7];
 
 uint8_t CS4272_Init(void);
 
-#define INT24_MAX 0x7FFFFF
+static inline __attribute__((always_inline)) float int24_t_to_f32(const int32_t in) {
+    return ((float)(in << 8)) / ((float)INT32_MAX);
+}
+
+static inline __attribute__((always_inline)) int32_t f32_to_int24_t(const float in) {
+    return ((int32_t)(in * ((float)INT32_MAX))) >> 8;
+}
 
 #endif /* INC_CS4272_H_ */
-- 
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