From 9cf2ca6453eb2f07342ef3beb92e82780abded01 Mon Sep 17 00:00:00 2001
From: Wolfgang Hottgenroth <wolfgang.hottgenroth@icloud.com>
Date: Mon, 3 Jun 2024 15:31:06 +0200
Subject: [PATCH] changes

---
 docs/calc-76489an.py | 64 ++++++++++++++++++++++++++++++++++++++++++++
 psg.c                | 12 +++++++--
 psg.h                |  2 +-
 3 files changed, 75 insertions(+), 3 deletions(-)
 create mode 100644 docs/calc-76489an.py

diff --git a/docs/calc-76489an.py b/docs/calc-76489an.py
new file mode 100644
index 0000000..e8ef518
--- /dev/null
+++ b/docs/calc-76489an.py
@@ -0,0 +1,64 @@
+N = 3579545.0
+factor = 1.0594631
+base = 440.0
+
+frequencies = []
+
+BEFORE_A = 46
+f = base
+for i in range (BEFORE_A):
+    idx = BEFORE_A - i - 1
+    print(f"{idx}: {f}")
+    frequencies.append(f)
+    f = base / factor
+    base = f
+frequencies.reverse()
+
+AFTER_A = 50
+base = 440.0
+for i in range(AFTER_A):
+    idx = BEFORE_A + i
+    f = base * factor
+    print(f"{idx}: {f}")
+    frequencies.append(f)
+    base = f
+
+# print(f"{frequencies}")
+
+codes = []
+for i in range(len(frequencies)):
+    codes.append(round(N / (32.0 * frequencies[i])))
+
+
+#const uint16_t frequencyCodes[8][12] = {
+#  //    C,   Cis,     D,   Dis,     E,     F,   Fis,     G,   Gis,     A,   Ais,     H
+#  { 06535, 06234, 05747, 05474, 05233, 05002, 04563, 04353, 04153, 03762, 03600, 03424 },  // Octave 1
+#  { 03256, 03116, 02764, 02636, 02515, 02401, 02271, 02165, 02065, 01771, 01700, 01612 },  // Octave 2
+#  { 01527, 01447, 01372, 01317, 01247, 01201, 01135, 01073, 01033, 00774, 00740, 00705 },  // Octave 3
+#  { 00654, 00624, 00575, 00550, 00523, 00500, 00456, 00435, 00415, 00376, 00360, 00342 },  // Octave 4
+#  { 00326, 00312, 00276, 00264, 00252, 00240, 00227, 00217, 00207, 00177, 00170, 00161 },  // Octave 5
+#  { 00153, 00145, 00137, 00132, 00125, 00120, 00114, 00107, 00103, 00100, 00074, 00071 },  // Octave 6
+#  { 00065, 00062, 00060, 00055, 00052, 00050, 00046, 00044, 00042, 00040, 00036, 00034 },  // Octave 7
+#  { 00033, 00031, 00030, 00026, 00025, 00024, 00023, 00022, 00021, 00020, 00017, 00016 }   // Octave 8
+#};
+
+
+
+print("const uint16_t frequencyCodes[8][12] = {")
+step = 12
+for i in range(len(codes)):
+    if (i % step == 0):
+        print("  { ", end='')
+    print(f"{codes[i]}", end='')
+    if ((i+1) % step != 0):
+        print(", ", end='')
+    if ((i+1) % step == 0):
+        print(" }", end='')
+        if ((i+1) != len(codes)):
+            print(", ")
+        else:
+            print()
+print("};")
+
+
+
diff --git a/psg.c b/psg.c
index dd387a5..57d2ca7 100644
--- a/psg.c
+++ b/psg.c
@@ -6,6 +6,8 @@
 #include "scheduler.h"
 
 
+const uint32_t BASE_FREQUENCY = 3579545;
+
 // based on 3.579545 MHz
 const uint16_t frequencyCodes[8][12] = {
   { 3420, 3229, 3047, 2876, 2715, 2562, 2419, 2283, 2155, 2034, 1920, 1812 }, 
@@ -76,7 +78,7 @@ inline static void WRITE_CYCLE(uint8_t chipNo) {
 //  WRITE_CYCLE(chipNo);
 //}
 
-static void psgWriteFrequency(uint8_t chip, uint8_t channel, uint16_t frequencyCode) {
+static void psgWriteFrequencyCode(uint8_t chip, uint8_t channel, uint16_t frequencyCode) {
   uint8_t chipNo = chip;
   uint8_t regAddr = (channel % 3) * 2;
 
@@ -132,10 +134,16 @@ void psgPlayTone(uint8_t chip, uint8_t channel, uint8_t volume, t_octave octave,
     psgAmplitude(chip, channel, 0);
   } else {
     psgAmplitude(chip, channel, volume);
-    psgWriteFrequency(chip, channel, frequencyCodes[octave][note]);
+    psgWriteFrequencyCode(chip, channel, frequencyCodes[octave][note]);
   }
 }
 
+void psgPlayFrequency(uint8_t chip, uint8_t channel, uint8_t volume, uint16_t frequency) {
+  uint16_t frequencyCode = BASE_FREQUENCY / (32 * frequency); 
+  psgAmplitude(chip, channel, volume);
+  psgWriteFrequencyCode(chip, channel, frequencyCode);
+}
+
 void psgInit() {
   // address/data bus
   P2DIR = 0xff;
diff --git a/psg.h b/psg.h
index 79bcda9..9171484 100644
--- a/psg.h
+++ b/psg.h
@@ -41,6 +41,6 @@ void psgInit();
 
 void psgPlayTone(uint8_t chip, uint8_t channel, uint8_t volume, t_octave octave, t_note note);
 void psgAmplitude(uint8_t chip, uint8_t channel, uint8_t volume);
-
+void psgPlayFrequency(uint8_t chip, uint8_t channel, uint8_t volume, uint16_t frequency);
 
 #endif // _PSG_H_