From 28c6366769b7b7c9d978e3fa1d83362e63caf831 Mon Sep 17 00:00:00 2001
From: Mitya Selivanov <automainint@guattari.tech>
Date: Thu, 15 Feb 2024 20:36:21 +0100
Subject: Update TODO

---
 source/saw/main.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 50 insertions(+), 2 deletions(-)

diff --git a/source/saw/main.c b/source/saw/main.c
index 02d94c4..f9773c0 100644
--- a/source/saw/main.c
+++ b/source/saw/main.c
@@ -52,6 +52,8 @@
 //
 
 #define TIME_EPS 0.0001
+#define REFERENCE_PITCH 440.0                  // A_4
+#define EQUAL_TEMPERAMENT_FACTOR 1.05946309436 // 2^(1/12)
 
 enum {
   //  TODO
@@ -69,6 +71,8 @@ enum {
   BUFFER_SIZE  = 1024 * 8,
 #endif
 
+  REFERENCE_PITCH_INDEX = 5 * 12, // index of A_4
+
 #ifdef __EMSCRIPTEN__
   TRACK_COUNT  = 8,
   ROLL_COUNT   = 16,
@@ -146,6 +150,7 @@ typedef struct {
   b8              enabled;
   i64             track;
   b8              pitch_turned_off[PITCH_COUNT];
+  f64             tuning[PITCH_COUNT];
   i64             rate;
   saw_roll_note_t notes[SHEET_SIZE];
   i64             time;
@@ -316,6 +321,18 @@ static f64 saw_ui_input_buffer = 0.;
 #  pragma GCC            optimize("O3")
 #endif
 
+static void saw_tuning_equal_temperament(f64 *tuning) {
+  assert(tuning != NULL);
+  if (tuning == NULL)
+    return;
+
+  for (i64 i = 0; i < PITCH_COUNT; ++i) {
+    tuning[i] = REFERENCE_PITCH *
+                pow(EQUAL_TEMPERAMENT_FACTOR,
+                    (f64) (i - REFERENCE_PITCH_INDEX));
+  }
+}
+
 static f64 saw_random(f64 min, f64 max) {
   if (max - min < .000001)
     return min;
@@ -1323,6 +1340,7 @@ static void saw_ui_compose(i64 x0, i64 y0, i64 width, i64 height) {
           .enabled          = 1,
           .track            = track,
           .pitch_turned_off = { 0 },
+          .tuning           = { 0 },
           .rate             = ROLL_DEFAULT_RATE,
           .notes            = { 0 },
           .time             = frame,
@@ -1340,6 +1358,8 @@ static void saw_ui_compose(i64 x0, i64 y0, i64 width, i64 height) {
           .loop_input        = 0,
         };
 
+        saw_tuning_equal_temperament(saw_rolls[n].tuning);
+
         saw_current_roll  = n;
         saw_current_track = track;
       }
@@ -2385,6 +2405,10 @@ static void saw_init(void) {
   //  Init Saw state
   //
 
+  f64 tuning[PITCH_COUNT];
+
+  saw_tuning_equal_temperament(tuning);
+
   for (i32 i = 0; i < ROLL_COUNT; i++) {
     saw_compose.rolls[i] = (i == 0 ? 0 : -1);
 
@@ -2393,6 +2417,7 @@ static void saw_init(void) {
       .track            = 0,
       .last_index       = -1,
       .pitch_turned_off = { 0 },
+      .tuning           = { 0 },
       .rate             = ROLL_DEFAULT_RATE,
       .notes            = { 0 },
       .time             = 0,
@@ -2408,6 +2433,8 @@ static void saw_init(void) {
       .ui_offset_y_input = 0,
       .loop_input        = 0,
     };
+
+    memcpy(saw_rolls[i].tuning, tuning, sizeof tuning);
   }
 
   for (i32 i = 0; i < TRACK_COUNT; i++)
@@ -2515,12 +2542,29 @@ static void saw_init(void) {
         return;
       }
 
-      for (i64 pitch = 0; pitch < pitch_count; pitch++) {
+      for (i64 pitch = 0; pitch < pitch_count; ++pitch) {
         i32 flag;
         SCAN_(" %d", 1, &flag);
         roll->pitch_turned_off[pitch] = flag ? 1 : 0;
       }
 
+#if 0
+      SCAN_(" tuning %d", 1, &pitch_count);
+
+      if (pitch_count < 0 || pitch_count > PITCH_COUNT) {
+        printf("Invalid tuning count: %d\n", pitch_count);
+        fflush(stdout);
+        fclose(f);
+        return;
+      }
+
+      for (i64 pitch = 0; pitch < pitch_count; ++pitch) {
+        i64 frequency;
+        SCAN_(" %lld", 1, &frequency);
+        roll->tuning[pitch] = .0001 * frequency;
+      }
+#endif
+
       SCAN_(" rate %lld", 1, &roll->rate);
 
       i32 sheet_size;
@@ -2857,8 +2901,12 @@ static void saw_cleanup(void) {
     fprintf(f, "enabled           %d\n", (i32) roll->enabled);
     fprintf(f, "track             %lld\n", roll->track);
     fprintf(f, "pitch_turned_off  %d\n ", PITCH_COUNT);
-    for (i64 pitch = 0; pitch < PITCH_COUNT; pitch++)
+    for (i64 pitch = 0; pitch < PITCH_COUNT; ++pitch)
       fprintf(f, " %d", (i32) roll->pitch_turned_off[pitch]);
+    fprintf(f, "tuning            %d\n ", PITCH_COUNT);
+    for (i64 pitch = 0; pitch < PITCH_COUNT; ++pitch)
+      fprintf(f, " %lld",
+              (i64) floor(roll->tuning[pitch] * 10000 + .5));
     fprintf(f, "\n");
     fprintf(f, "rate              %lld\n", roll->rate);
 
-- 
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