From 2c9abb4f74e65c330a9ed8d84031f62bf1057215 Mon Sep 17 00:00:00 2001
From: Craig <craig.collier@ro.co>
Date: Wed, 21 Aug 2024 17:16:07 -0700
Subject: [PATCH] align with 1tcycle apu ticks

---
 src/apu.zig | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/apu.zig b/src/apu.zig
index 65cf26d..8dc4f19 100644
--- a/src/apu.zig
+++ b/src/apu.zig
@@ -559,7 +559,7 @@ pub const APU = struct {
                     self.channel_1.shadow_frequency = self.channel_1._frequency;
                     self.channel_1.sweep_timer = if (self.channel_1.nr10.sweep_pace == 0) 8 else self.channel_1.nr10.sweep_pace;
                     self.channel_1.sweep_enable = if (self.channel_1.nr10.sweep_pace > 0 or self.channel_1.nr10.sweep_step > 0) true else false;
-                    self.channel_1.timer = (2048 - self.channel_1.frequency);
+                    self.channel_1.timer = (2048 - self.channel_1.frequency) * 4;
                 }
             },
             0xFF15 => {},
@@ -588,7 +588,7 @@ pub const APU = struct {
                     self.channel_2.enabled = true;
                     self.channel_2.length_timer = 64 - @as(u16, self.channel_2.nr21.sound_length);
                     self.channel_2.volume = self.channel_2.nr22.env_initial_volume;
-                    self.channel_2.timer = (2048 - freq);
+                    self.channel_2.timer = (2048 - freq) * 4;
                     self.channel_2.envelope_timer = self.channel_2.nr22.env_sweep_pace;
                 }
             },
@@ -621,7 +621,7 @@ pub const APU = struct {
                     // ?
                     self.channel_3.current_sample = 0;
                     self.channel_3.length_timer = 256 - @as(u16, self.channel_3.nr31.initial_length_timer);
-                    self.channel_3.timer = (2048 - freq) / 2;
+                    self.channel_3.timer = (2048 - freq) * 2;
                 }
             },
             0xFF20 => {
@@ -640,7 +640,7 @@ pub const APU = struct {
                 self.channel_4.nr44 = @bitCast(byte | 0b0011_1111);
                 if (self.channel_4.nr44.trigger) {
                     self.channel_4.enabled = true;
-                    self.channel_4.timer = self.channel_4.freq() / 4;
+                    self.channel_4.timer = self.channel_4.freq();
                     self.channel_4.length_timer = 64 - @as(u16, self.channel_4.nr41.initial_length_timer);
                     self.channel_4.volume = self.channel_4.nr42.env_initial_volume;
                     self.channel_4.envelope_timer = self.channel_4.nr42.env_sweep_pace;
@@ -748,7 +748,7 @@ const Channel1 = struct {
         // log.debug("before self.duty_pos = {}", .{self.ch1_duty_pos});
         self.timer -%= 1;
         if (self.timer == 0) {
-            self.timer = (2048 - self.frequency);
+            self.timer = (2048 - self.frequency) * 4;
             self.duty_pos = (self.duty_pos + 1) % 8;
         }
         // log.debug("after self.duty_pos = {}", .{self.ch1_duty_pos});
@@ -772,7 +772,7 @@ const Channel1 = struct {
         if (apu.envelope_step and self.nr12.env_sweep_pace != 0) {
             self.envelope_timer -%= 1;
             if (self.envelope_timer == 0) {
-                self.envelope_timer = self.nr12.env_sweep_pace / 4;
+                self.envelope_timer = self.nr12.env_sweep_pace;
                 if (self.nr12.env_direction and self.volume != 0xF) {
                     self.volume += 1;
                 }
@@ -862,7 +862,7 @@ const Channel2 = struct {
         }
 
         const freq: u16 = @as(u16, self.nr24.period_high) << 8 | @as(u16, self.nr23.period_low);
-        const initial_freq = (2048 - freq);
+        const initial_freq = (2048 - freq) * 4;
         self.timer -%= 1;
         if (self.timer == 0) {
             self.timer = initial_freq;
@@ -960,7 +960,7 @@ const Channel3 = struct {
         }
 
         const freq: u16 = @as(u16, self.nr34.period_high) << 8 | @as(u16, self.nr33.period_low);
-        const initial_freq = (2048 - freq) / 2;
+        const initial_freq = (2048 - freq) * 2;
         // const initial_freq = (2048 - freq);
         self.timer -%= 1;
         if (self.timer == 0) {
@@ -1072,7 +1072,7 @@ const Channel4 = struct {
 
         self.timer -%= 1;
         if (self.timer == 0) {
-            self.timer = self.freq() / 4;
+            self.timer = self.freq();
 
             const lsfr_bit0 = self.lsfr & 1;
             const lsfr_bit1 = (self.lsfr >> 1) & 1;