From 9328e22425c6e86dc1636c60e41a5fda4d5f17d3 Mon Sep 17 00:00:00 2001
From: Wolfgang Hottgenroth <wolfgang.hottgenroth@icloud.com>
Date: Fri, 29 Mar 2024 14:11:36 +0100
Subject: [PATCH] pace calculation works

---
 sound-driver/melody.c    |  2 +-
 sound-driver/sequencer.c | 25 ++++++++++++++++++++++---
 sound-driver/sequencer.h | 22 ++++++++++++----------
 3 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/sound-driver/melody.c b/sound-driver/melody.c
index e51f508..8e183e5 100644
--- a/sound-driver/melody.c
+++ b/sound-driver/melody.c
@@ -898,7 +898,7 @@ const t_tone tetris3[] = {
 t_melodies tetrisTheme = {
   .melodies = { { .amplitude = 3, .tones = tetris1 }, { .amplitude = 3, .tones = tetris2 }, { .amplitude = 3, .tones = tetris3 } },
   .numOfMelodies = 3,
-  .pace = 4
+  .pace = 160
 };
 
 void melodyInit() {
diff --git a/sound-driver/sequencer.c b/sound-driver/sequencer.c
index 648dde5..966de34 100644
--- a/sound-driver/sequencer.c
+++ b/sound-driver/sequencer.c
@@ -1,3 +1,5 @@
+#include <stdint.h>
+#include <stdbool.h>
 #include <sys/param.h>
 #include "sequencer.h"
 #include "scheduler.h"
@@ -9,8 +11,24 @@ void sequencerInit() {
 }
 
 void sequencerExec(void *handle) {  
+  static uint16_t lengths[e_L_LengthEnd];
   t_melodies *melodies = (t_melodies*) handle;
 
+  if (melodies->firstRun) {
+    melodies->firstRun = false;
+
+    lengths[e_L_1_4]  = 60000 / melodies->pace; // duration of a 1/4 tone in ms
+    lengths[e_L_1_2]  = lengths[e_L_1_4] << 1;
+    lengths[e_L_1]    = lengths[e_L_1_4] << 2;
+    lengths[e_L_1_8]  = lengths[e_L_1_4] >> 1;
+    lengths[e_L_1_16] = lengths[e_L_1_4] >> 2;
+    lengths[e_L_1_32] = lengths[e_L_1_4] >> 4;
+
+    for (uint8_t i = 0; i < e_L_LengthEnd; i++) {
+      lengths[i] /= SEQUENCER_PERIOD;
+    }
+  }
+
   for (uint8_t channel = 0; channel < melodies->numOfMelodies; channel++) {
     t_melody *melody = &(melodies->melodies[channel]);
 
@@ -31,7 +49,7 @@ void sequencerExec(void *handle) {
             melody->idx = 0;
           }
           psgPlayTone(channel, melody->tones[melody->idx].octave, melody->tones[melody->idx].note);
-          melody->lengthCnt = (melody->tones[melody->idx].staccato) ? (melody->tones[melody->idx].length / 2) : melody->tones[melody->idx].length;
+          melody->lengthCnt = (melody->tones[melody->idx].staccato) ? (lengths[melody->tones[melody->idx].length] / 2) : lengths[melody->tones[melody->idx].length];
           melody->state = e_HoldTone;
         }
         break;
@@ -48,7 +66,7 @@ void sequencerExec(void *handle) {
         break;
       case e_StaccatoBreak:
         psgPlayTone(channel, e_O_Null, e_Pause);
-        melody->lengthCnt = melody->tones[melody->idx].length / 2;
+        melody->lengthCnt = lengths[melody->tones[melody->idx].length] / 2;
         melody->state = e_HoldStaccatoBreak;
         break;
       case e_HoldStaccatoBreak:
@@ -75,7 +93,8 @@ uint16_t sequencerPlayMelodies(t_melodies *melodies) {
     melodies->melodies[i].state = e_Init;
   }
   melodies->sync = 0;
+  melodies->firstRun = true;
 
-  return schAdd(sequencerExec, (void*) melodies, 0, melodies->pace);
+  return schAdd(sequencerExec, (void*) melodies, 0, SEQUENCER_PERIOD);
 }
 
diff --git a/sound-driver/sequencer.h b/sound-driver/sequencer.h
index 8717a72..d5a43f1 100644
--- a/sound-driver/sequencer.h
+++ b/sound-driver/sequencer.h
@@ -7,14 +7,15 @@
 #include "psg.h"
 
 typedef enum {
-  e_L_EndMark = 0,
-  e_L_SyncMark = 1,
-  e_L_1 = 320,
-  e_L_1_2 = 160,
-  e_L_1_4 = 80,
-  e_L_1_8 = 40,
-  e_L_1_16 = 20,
-  e_L_1_32 = 10,
+  e_L_1 = 0,
+  e_L_1_2 = 1,
+  e_L_1_4 = 2,
+  e_L_1_8 = 3,
+  e_L_1_16 = 4,
+  e_L_1_32 = 5,
+  e_L_LengthEnd = 6,
+  e_L_EndMark = 254,
+  e_L_SyncMark = 255,
 } t_noteLength;
 
 typedef struct {
@@ -43,16 +44,17 @@ typedef struct {
   const t_tone *tones;
 } t_melody;
 
+#define SEQUENCER_PERIOD 4 // ms
 #define NUM_OF_CHANNELS 3
 typedef struct {
   uint8_t numOfMelodies;
-  uint8_t pace;
+  bool firstRun;
+  uint8_t pace; // quarter notes per minute
   uint8_t sync;
   t_melody melodies[NUM_OF_CHANNELS];
 } t_melodies;
 
 void sequencerInit();
-uint16_t sequencerPlayMelody(t_melody *melody);
 uint16_t sequencerPlayMelodies(t_melodies *melodies);