style: code refactoring

src/core/apu.zig

@@ -306,15 +306,15 @@ pub const Apu = struct {
         };
 
         // Add all PSG channels together
-        left += if (ch_left & 1 == 1) self.ch1.amplitude() else 0;
+        left += if (ch_left & 1 == 1) @as(i16, self.ch1.sample) else 0;
-        left += if (ch_left >> 1 & 1 == 1) self.ch2.amplitude() else 0;
+        left += if (ch_left >> 1 & 1 == 1) @as(i16, self.ch2.sample) else 0;
-        left += if (ch_left >> 2 & 1 == 1) self.ch3.amplitude() else 0;
+        left += if (ch_left >> 2 & 1 == 1) @as(i16, self.ch3.sample) else 0;
-        left += if (ch_left >> 3 == 1) self.ch4.amplitude() else 0;
+        left += if (ch_left >> 3 == 1) @as(i16, self.ch4.sample) else 0;
 
-        right += if (ch_right & 1 == 1) self.ch1.amplitude() else 0;
+        right += if (ch_right & 1 == 1) @as(i16, self.ch1.sample) else 0;
-        right += if (ch_right >> 1 & 1 == 1) self.ch2.amplitude() else 0;
+        right += if (ch_right >> 1 & 1 == 1) @as(i16, self.ch2.sample) else 0;
-        right += if (ch_right >> 2 & 1 == 1) self.ch3.amplitude() else 0;
+        right += if (ch_right >> 2 & 1 == 1) @as(i16, self.ch3.sample) else 0;
-        right += if (ch_right >> 3 == 1) self.ch4.amplitude() else 0;
+        right += if (ch_right >> 3 == 1) @as(i16, self.ch4.sample) else 0;
 
         // Multiply by master channel volume
         left *= 1 + @as(i16, self.psg_cnt.left_vol.read());

src/core/apu/Noise.zig

@@ -1,4 +1,5 @@
 const io = @import("../bus/io.zig");
+const util = @import("../../util.zig");
 
 const Scheduler = @import("../scheduler.zig").Scheduler;
 const FrameSequencer = @import("../apu.zig").FrameSequencer;
@@ -123,7 +124,7 @@ pub fn setNr44(self: *Self, fs: *const FrameSequencer, byte: u8) void {
         self.enabled = self.isDacEnabled();
     }
 
-    self.lfsr.updateLength(fs, self, new);
+    util.audio.length.ch4.update(self, fs, new);
     self.cnt = new;
 }
 
@@ -135,10 +136,6 @@ pub fn channelTimerOverflow(self: *Self, late: u64) void {
     self.sample = if (self.enabled) self.lfsr.sample() * @as(i8, self.env_dev.vol) else 0;
 }
 
-pub fn amplitude(self: *const Self) i16 {
-    return @as(i16, self.sample);
-}
-
 fn isDacEnabled(self: *const Self) bool {
     return self.envelope.raw & 0xF8 != 0x00;
 }

src/core/apu/Tone.zig

@@ -1,4 +1,5 @@
 const io = @import("../bus/io.zig");
+const util = @import("../../util.zig");
 
 const Scheduler = @import("../scheduler.zig").Scheduler;
 const FrameSequencer = @import("../apu.zig").FrameSequencer;
@@ -65,10 +66,6 @@ pub fn channelTimerOverflow(self: *Self, late: u64) void {
     self.sample = if (self.enabled) self.square.sample(self.duty) * @as(i8, self.env_dev.vol) else 0;
 }
 
-pub fn amplitude(self: *const Self) i16 {
-    return @as(i16, self.sample);
-}
-
 /// NR21, NR22
 pub fn getSoundCntL(self: *const Self) u16 {
     return @as(u16, self.envelope.raw) << 8 | (self.duty.raw & 0xC0);
@@ -131,7 +128,7 @@ pub fn setNr24(self: *Self, fs: *const FrameSequencer, byte: u8) void {
         self.enabled = self.isDacEnabled();
     }
 
-    self.square.updateLength(Self, fs, self, new);
+    util.audio.length.update(Self, self, fs, new);
     self.freq = new;
 }
 

src/core/apu/ToneSweep.zig

@@ -1,5 +1,5 @@
-// const std = @import("std");
 const io = @import("../bus/io.zig");
+const util = @import("../../util.zig");
 
 const Scheduler = @import("../scheduler.zig").Scheduler;
 const FrameSequencer = @import("../apu.zig").FrameSequencer;
@@ -79,10 +79,6 @@ pub fn channelTimerOverflow(self: *Self, late: u64) void {
     self.sample = if (self.enabled) self.square.sample(self.duty) * @as(i8, self.env_dev.vol) else 0;
 }
 
-pub fn amplitude(self: *const Self) i16 {
-    return @as(i16, self.sample);
-}
-
 /// NR10, NR11, NR12
 pub fn setSoundCnt(self: *Self, value: u32) void {
     self.setSoundCntL(@truncate(u8, value));
@@ -181,7 +177,7 @@ pub fn setNr14(self: *Self, fs: *const FrameSequencer, byte: u8) void {
         self.enabled = self.isDacEnabled();
     }
 
-    self.square.updateLength(Self, fs, self, new);
+    util.audio.length.update(Self, self, fs, new);
     self.freq = new;
 }
 

src/core/apu/Wave.zig

@@ -1,4 +1,5 @@
 const io = @import("../bus/io.zig");
+const util = @import("../../util.zig");
 
 const Scheduler = @import("../scheduler.zig").Scheduler;
 const FrameSequencer = @import("../apu.zig").FrameSequencer;
@@ -111,7 +112,7 @@ pub fn setNr34(self: *Self, fs: *const FrameSequencer, byte: u8) void {
         self.enabled = self.select.enabled.read();
     }
 
-    self.wave_dev.updateLength(fs, self, new);
+    util.audio.length.update(Self, self, fs, new);
     self.freq = new;
 }
 
@@ -123,7 +124,3 @@ pub fn channelTimerOverflow(self: *Self, late: u64) void {
     // Convert unsigned 4-bit wave sample to signed 8-bit sample
     self.sample = (2 * @as(i8, self.wave_dev.sample(self.select)) - 15) >> self.wave_dev.shift(self.vol);
 }
-
-pub fn amplitude(self: *const Self) i16 {
-    return @as(i16, self.sample);
-}

src/core/apu/signal/Lfsr.zig

@@ -25,22 +25,6 @@ pub fn sample(self: *const Self) i8 {
     return if ((~self.shift & 1) == 1) 1 else -1;
 }
 
-/// Update the sate of the Channel Length TImer
-pub fn updateLength(_: *Self, fs: *const FrameSequencer, ch4: *Noise, nr44: io.NoiseControl) void {
-    // Write to NRx4 when FS's next step is not one that clocks the length counter
-    if (!fs.isLengthNext()) {
-        // If length_enable was disabled but is now enabled and length timer is not 0 already,
-        // decrement the length timer
-
-        if (!ch4.cnt.length_enable.read() and nr44.length_enable.read() and ch4.len_dev.timer != 0) {
-            ch4.len_dev.timer -= 1;
-
-            // If Length Timer is now 0 and trigger is clear, disable the channel
-            if (ch4.len_dev.timer == 0 and !nr44.trigger.read()) ch4.enabled = false;
-        }
-    }
-}
-
 /// Reload LFSR Timer
 pub fn reload(self: *Self, poly: io.PolyCounter) void {
     self.sched.removeScheduledEvent(.{ .ApuChannel = 3 });

src/core/apu/signal/Square.zig

@@ -21,23 +21,6 @@ pub fn init(sched: *Scheduler) Self {
     };
 }
 
-/// Updates the State of either Ch1 or Ch2's Length Timer
-pub fn updateLength(_: *const Self, comptime T: type, fs: *const FrameSequencer, ch: *T, nrx34: io.Frequency) void {
-    comptime std.debug.assert(T == ToneSweep or T == Tone);
-    // Write to NRx4 when FS's next step is not one that clocks the length counter
-    if (!fs.isLengthNext()) {
-        // If length_enable was disabled but is now enabled and length timer is not 0 already,
-        // decrement the length timer
-
-        if (!ch.freq.length_enable.read() and nrx34.length_enable.read() and ch.len_dev.timer != 0) {
-            ch.len_dev.timer -= 1;
-
-            // If Length Timer is now 0 and trigger is clear, disable the channel
-            if (ch.len_dev.timer == 0 and !nrx34.trigger.read()) ch.enabled = false;
-        }
-    }
-}
-
 /// Scheduler Event Handler for Square Synth Timer Expire
 pub fn onSquareTimerExpire(self: *Self, comptime T: type, nrx34: io.Frequency, late: u64) void {
     comptime std.debug.assert(T == ToneSweep or T == Tone);

src/core/apu/signal/Wave.zig

@@ -77,19 +77,3 @@ pub fn shift(_: *const Self, nr32: io.WaveVolume) u2 {
         0b11 => 2, // 25% Volume
     };
 }
-
-/// Update state of Channel 3 Length Device
-pub fn updateLength(_: *Self, fs: *const FrameSequencer, ch3: *Wave, nrx34: io.Frequency) void {
-    // Write to NRx4 when FS's next step is not one that clocks the length counter
-    if (!fs.isLengthNext()) {
-        // If length_enable was disabled but is now enabled and length timer is not 0 already,
-        // decrement the length timer
-
-        if (!ch3.freq.length_enable.read() and nrx34.length_enable.read() and ch3.len_dev.timer != 0) {
-            ch3.len_dev.timer -= 1;
-
-            // If Length Timer is now 0 and trigger is clear, disable the channel
-            if (ch3.len_dev.timer == 0 and !nrx34.trigger.read()) ch3.enabled = false;
-        }
-    }
-}

src/util.zig

@@ -158,17 +158,6 @@ pub const io = struct {
         }
     };
 };
-pub fn readUndefined(log: anytype, comptime format: []const u8, args: anytype) u8 {
-    log.warn(format, args);
-    if (builtin.mode == .Debug) std.debug.panic("TODO: Implement I/O Register", .{});
-
-    return 0;
-}
-
-pub fn writeUndefined(log: anytype, comptime format: []const u8, args: anytype) void {
-    log.warn(format, args);
-    if (builtin.mode == .Debug) std.debug.panic("TODO: Implement I/O Register", .{});
-}
 
 pub const Logger = struct {
     const Self = @This();
@@ -230,3 +219,52 @@ pub const Logger = struct {
 };
 
 const FmtArgTuple = std.meta.Tuple(&.{ u32, u32, u32, u32, u32, u32, u32, u32, u32, u32, u32, u32, u32, u32, u32, u32, u32, u32 });
+
+pub const audio = struct {
+    const _io = @import("core/bus/io.zig");
+
+    const ToneSweep = @import("core/apu/ToneSweep.zig");
+    const Tone = @import("core/apu/Tone.zig");
+    const Wave = @import("core/apu/Wave.zig");
+    const Noise = @import("core/apu/Noise.zig");
+
+    pub const length = struct {
+        const FrameSequencer = @import("core/apu.zig").FrameSequencer;
+
+        /// Update State of Ch1, Ch2 and Ch3 length timer
+        pub fn update(comptime T: type, self: *T, fs: *const FrameSequencer, nrx34: _io.Frequency) void {
+            comptime std.debug.assert(T == ToneSweep or T == Tone or T == Wave);
+
+            // Write to NRx4 when FS's next step is not one that clocks the length counter
+            if (!fs.isLengthNext()) {
+                // If length_enable was disabled but is now enabled and length timer is not 0 already,
+                // decrement the length timer
+
+                if (!self.freq.length_enable.read() and nrx34.length_enable.read() and self.len_dev.timer != 0) {
+                    self.len_dev.timer -= 1;
+
+                    // If Length Timer is now 0 and trigger is clear, disable the channel
+                    if (self.len_dev.timer == 0 and !nrx34.trigger.read()) self.enabled = false;
+                }
+            }
+        }
+
+        pub const ch4 = struct {
+            /// update state of ch4 length timer
+            pub fn update(self: *Noise, fs: *const FrameSequencer, nr44: _io.NoiseControl) void {
+                // Write to NRx4 when FS's next step is not one that clocks the length counter
+                if (!fs.isLengthNext()) {
+                    // If length_enable was disabled but is now enabled and length timer is not 0 already,
+                    // decrement the length timer
+
+                    if (!self.cnt.length_enable.read() and nr44.length_enable.read() and self.len_dev.timer != 0) {
+                        self.len_dev.timer -= 1;
+
+                        // If Length Timer is now 0 and trigger is clear, disable the channel
+                        if (self.len_dev.timer == 0 and !nr44.trigger.read()) self.enabled = false;
+                    }
+                }
+            }
+        };
+    };
+};