From 210dc81b251b491144b401f699f8221ba783f9e0 Mon Sep 17 00:00:00 2001
From: rkcf <rkcf@rkcf.me>
Date: Fri, 24 Feb 2023 17:56:27 -0600
Subject: [PATCH] Feat: add sine wave lookup table generation

Refs: #12
---
 src/main/CMakeLists.txt           |  2 +-
 src/main/esp32_eurorack_generic.c |  5 +++++
 src/main/wavetable.c              | 35 +++++++++++++++++++++++++++++++
 src/main/wavetable.h              |  7 +++++++
 4 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 src/main/wavetable.c
 create mode 100644 src/main/wavetable.h

diff --git a/src/main/CMakeLists.txt b/src/main/CMakeLists.txt
index b48d63e..cf31283 100644
--- a/src/main/CMakeLists.txt
+++ b/src/main/CMakeLists.txt
@@ -1,2 +1,2 @@
-idf_component_register(SRCS "esp32_eurorack_generic.c"
+idf_component_register(SRCS "esp32_eurorack_generic.c" "wavetable.c"
                     INCLUDE_DIRS ".")
diff --git a/src/main/esp32_eurorack_generic.c b/src/main/esp32_eurorack_generic.c
index e36297c..f0110d0 100644
--- a/src/main/esp32_eurorack_generic.c
+++ b/src/main/esp32_eurorack_generic.c
@@ -8,6 +8,8 @@
 #include "freertos/portmacro.h"
 #include "hal/i2c_types.h"
 
+#include "wavetable.h"
+
 /* DAC Peripheral Config */
 #define DAC_SCL_PIN 12
 #define DAC_SDA_PIN 13
@@ -117,6 +119,9 @@ void app_main(void)
     ESP_LOGI(TAG, "Sucessfully initialized DAC");
   }
 
+  /* Generate wave tables */
+  gen_wavetables();
+
   /* Loop to test DAC output */
   while (1) {
     dac_out_test();
diff --git a/src/main/wavetable.c b/src/main/wavetable.c
new file mode 100644
index 0000000..20340fd
--- /dev/null
+++ b/src/main/wavetable.c
@@ -0,0 +1,35 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <math.h>
+#include <sys/types.h>
+
+#include "esp_log.h"
+
+#include "wavetable.h"
+
+#define SAMPLE_RATE 22000 /* 22kHz  */
+#define FREQ 440
+#define TIME 1
+
+float_t *sin_tbl;
+
+static const char *TAG = "wavetable";
+
+static void gen_sin_table(void)
+{
+  /* Allocate memory */
+  uint16_t table_length = 1024; /* TODO make this accurate to sample rate and frequency */
+  sin_tbl = (float *)malloc(sizeof(float) * table_length);
+
+  /* Loop through values and store in table */
+  for (uint16_t i = 0; i < table_length; i++) {
+    sin_tbl[i] = sin((2 * M_PI * i) / table_length);
+  }
+}
+
+void gen_wavetables(void)
+{
+  ESP_LOGI(TAG, "Generating sine wavetable");
+  gen_sin_table();
+}
diff --git a/src/main/wavetable.h b/src/main/wavetable.h
new file mode 100644
index 0000000..b173928
--- /dev/null
+++ b/src/main/wavetable.h
@@ -0,0 +1,7 @@
+#ifndef WAVETABLE_H_ /* Guard */
+#define WAVETABLE_H_
+
+/* Generates all wavetables */
+void gen_wavetables(void);
+
+#endif