sapemu: TONS of internal state & access sequencing work

with some exceptions, this should be everything needed for accessing memory and cpu-exposed registers in a cycle-accurate way.

sapemu/src/dsp/audio_processing.rs

@@ -0,0 +1,9 @@
+//! Audio processing code for the DSP.
+
+use super::Dsp;
+use crate::memory::Memory;
+
+impl Dsp {
+	#[allow(clippy::needless_pass_by_ref_mut, clippy::unused_self)]
+	pub(super) fn run_audio_processing(&mut self, memory: &mut Memory) {}
+}

sapemu/src/dsp/registers.rs

@@ -5,77 +5,79 @@ use std::ops::Deref;
 
 use bitflags::bitflags;
 
+use super::tables::RATE_TABLE;
+
 /// All DSP registers exposed to the SMP.
 #[derive(Copy, Clone, Debug)]
 pub struct DspRegisters {
 	/// x0-x9, per-voice registers `VxVOLL` - `VxOUTX`
-	voices:               [VoiceRegisters; 8],
+	pub(super) voices:                 [VoiceRegisters; 8],
 	/// 0C, MVOLL
-	main_volume_left:     u8,
+	pub(super) main_volume_left:       u8,
 	/// 1C, MVOLR
-	main_volume_right:    u8,
+	pub(super) main_volume_right:      u8,
 	/// 2C, EVOLL
-	echo_volume_left:     u8,
+	pub(super) echo_volume_left:       u8,
 	/// 3C, EVOLR
-	echo_volume_right:    u8,
+	pub(super) echo_volume_right:      u8,
 	/// 4C, KON
-	key_on:               PerVoiceFlag,
+	pub(super) key_on:                 PerVoiceFlag,
 	/// 5C, KOFF
-	key_off:              PerVoiceFlag,
+	pub(super) key_off:                PerVoiceFlag,
 	/// 6C, FLG
-	flags:                DspFlags,
+	pub(super) flags:                  DspFlags,
 	/// 7C, ENDX
-	voice_end:            PerVoiceFlag,
+	pub(super) voice_end:              PerVoiceFlag,
 	/// 0D, EFB
-	echo_feedback_volume: u8,
+	pub(super) echo_feedback_volume:   u8,
 	/// 2D, PMON
-	pitch_mod_enable:     PerVoiceFlag,
+	pub(super) pitch_mod_enable:       PerVoiceFlag,
 	/// 3D, NON
-	noise_enable:         PerVoiceFlag,
+	pub(super) noise_enable:           PerVoiceFlag,
 	/// 4D, EON
-	echo_enable:          PerVoiceFlag,
+	pub(super) echo_enable:            PerVoiceFlag,
 	/// 5D, DIR
-	sample_table_address: u8,
+	pub(super) sample_directory_index: u8,
 	/// 6D, ESA 🚀
-	echo_buffer_address:  u8,
+	pub(super) echo_source:            u8,
 	/// 7D, EDL
-	echo_delay:           u8,
+	pub(super) echo_delay:             u8,
 	/// xF, `FIRx`
-	fir_coefficients:     [u8; 8],
+	pub(super) fir_coefficients:       [u8; 8],
 	/// xA, unused
-	unused_a:             [u8; 8],
+	pub(super) unused_a:               [u8; 8],
 	/// xB, unused
-	unused_b:             [u8; 8],
+	pub(super) unused_b:               [u8; 8],
 	/// 1D, unused
-	unused_1d:            u8,
+	pub(super) unused_1d:              u8,
 	/// xE, unused
-	unused_e:             [u8; 8],
+	pub(super) unused_e:               [u8; 8],
 }
 
 impl Default for DspRegisters {
 	fn default() -> Self {
 		Self {
-			voices:               Default::default(),
-			main_volume_left:     Default::default(),
-			main_volume_right:    Default::default(),
-			echo_volume_left:     Default::default(),
-			echo_volume_right:    Default::default(),
-			key_on:               PerVoiceFlag::default(),
-			key_off:              PerVoiceFlag::default(),
-			flags:                DspFlags::default(),
-			voice_end:            PerVoiceFlag(0xff),
-			echo_feedback_volume: Default::default(),
-			pitch_mod_enable:     PerVoiceFlag::default(),
-			noise_enable:         PerVoiceFlag::default(),
-			echo_enable:          PerVoiceFlag::default(),
-			sample_table_address: Default::default(),
-			echo_buffer_address:  Default::default(),
-			echo_delay:           Default::default(),
-			fir_coefficients:     Default::default(),
-			unused_a:             Default::default(),
-			unused_b:             Default::default(),
-			unused_1d:            Default::default(),
-			unused_e:             Default::default(),
+			voices:                 Default::default(),
+			main_volume_left:       Default::default(),
+			main_volume_right:      Default::default(),
+			echo_volume_left:       Default::default(),
+			echo_volume_right:      Default::default(),
+			key_on:                 PerVoiceFlag::default(),
+			key_off:                PerVoiceFlag::default(),
+			flags:                  DspFlags::default(),
+			voice_end:              PerVoiceFlag(0xff),
+			echo_feedback_volume:   Default::default(),
+			pitch_mod_enable:       PerVoiceFlag::default(),
+			noise_enable:           PerVoiceFlag::default(),
+			echo_enable:            PerVoiceFlag::default(),
+			sample_directory_index: Default::default(),
+			echo_source:            Default::default(),
+			echo_delay:             Default::default(),
+			fir_coefficients:       Default::default(),
+			unused_a:               Default::default(),
+			unused_b:               Default::default(),
+			unused_1d:              Default::default(),
+			unused_e:               Default::default(),
 		}
 	}
 }
@@ -105,8 +107,8 @@ impl DspRegisters {
 			(0x2, 0xD) => self.pitch_mod_enable.0,
 			(0x3, 0xD) => self.noise_enable.0,
 			(0x4, 0xD) => self.echo_enable.0,
-			(0x5, 0xD) => self.sample_table_address,
-			(0x6, 0xD) => self.echo_buffer_address,
+			(0x5, 0xD) => self.sample_directory_index,
+			(0x6, 0xD) => self.echo_source,
 			(0x7, 0xD) => self.echo_delay,
 			(_, 0xF) => self.fir_coefficients[upper_nibble as usize],
 			_ => unreachable!(),
@@ -139,34 +141,62 @@ impl DspRegisters {
 			(0x2, 0xD) => self.pitch_mod_enable.0 = value,
 			(0x3, 0xD) => self.noise_enable.0 = value,
 			(0x4, 0xD) => self.echo_enable.0 = value,
-			(0x5, 0xD) => self.sample_table_address = value,
-			(0x6, 0xD) => self.echo_buffer_address = value,
+			(0x5, 0xD) => self.sample_directory_index = value,
+			(0x6, 0xD) => self.echo_source = value,
 			(0x7, 0xD) => self.echo_delay = value,
 			(_, 0xF) => self.fir_coefficients[upper_nibble as usize] = value,
 			_ => unreachable!(),
 		}
 	}
+
+	/// Returns the actual address of the sample directory.
+	#[must_use]
+	pub const fn sample_directory(&self) -> u16 {
+		self.sample_directory_index as u16 * 0x100
+	}
+
+	/// Returns the noise frequency divider from the flags register.
+	#[must_use]
+	pub fn noise_frequency(&self) -> u16 {
+		RATE_TABLE[(self.flags & DspFlags::NOISE_FREQUENCY).0 as usize]
+	}
+
+	/// Returns the number of samples that the echo buffer delays by.
+	#[must_use]
+	pub const fn echo_delay_samples(&self) -> u16 {
+		self.echo_delay as u16 * 2048
+	}
+
+	/// Returns the base address of the echo ring buffer in memory.
+	#[must_use]
+	pub const fn echo_base_address(&self) -> u16 {
+		self.echo_source as u16 * 256
+	}
 }
 
 /// Per-voice registers, x0 - xB
 #[derive(Clone, Copy, Debug, Default)]
 pub struct VoiceRegisters {
 	/// 0, VOLL
-	volume_left:    u8,
+	pub(super) volume_left:    u8,
 	/// 1, VOLR
-	volume_right:   u8,
-	/// 2, PITCHL and 3, PITCHH
-	pitch:          u16,
+	pub(super) volume_right:   u8,
+	/// 2, PITCHL
+	pub(super) pitch_low:      u8,
+	/// 3, PITCHH
+	pub(super) pitch_high:     u8,
 	/// 4, SRCN
-	sample_number:  u8,
-	/// 5, ADSR1 (low) and 6, ADSR2 (high)
-	adsr_settings:  AdsrSettings,
+	pub(super) sample_number:  u8,
+	/// 5, ADSR1 (low)
+	pub(super) adsr_low:       u8,
+	/// 6, ADSR2 (high)
+	pub(super) adsr_high:      u8,
 	/// 7, GAIN
-	gain_settings:  u8,
+	pub(super) gain_settings:  u8,
 	/// 8, ENVX
-	envelope_value: u8,
+	pub(super) envelope_value: u8,
 	/// 9, OUTX
-	output_value:   u8,
+	pub(super) output_value:   u8,
 }
 
 impl VoiceRegisters {
@@ -175,11 +205,11 @@ impl VoiceRegisters {
 		match address {
 			0 => self.volume_left,
 			1 => self.volume_right,
-			2 => self.pitch.to_le_bytes()[0],
-			3 => self.pitch.to_le_bytes()[1],
+			2 => self.pitch_low,
+			3 => self.pitch_high,
 			4 => self.sample_number,
-			5 => self.adsr_settings.to_be_bytes()[0],
-			6 => self.adsr_settings.to_be_bytes()[1],
+			5 => self.adsr_low,
+			6 => self.adsr_high,
 			7 => self.gain_settings,
 			8 => self.envelope_value,
 			9 => self.output_value,
@@ -192,11 +222,11 @@ impl VoiceRegisters {
 		match address {
 			0 => self.volume_left = value,
 			1 => self.volume_right = value,
-			2 => self.pitch = (self.pitch & 0xf0) | u16::from(value),
-			3 => self.pitch = (self.pitch & 0xf) | (u16::from(value) << 8),
+			2 => self.pitch_low = value,
+			3 => self.pitch_high = value,
 			4 => self.sample_number = value,
-			5 => self.adsr_settings.0 = (self.adsr_settings.0 & 0xf0) | u16::from(value),
-			6 => self.adsr_settings.0 = (self.adsr_settings.0 & 0xf) | (u16::from(value) << 8),
+			5 => self.adsr_low = value,
+			6 => self.adsr_high = value,
 			7 => self.gain_settings = value,
 			8 => self.envelope_value = value,
 			9 => self.output_value = value,
@@ -210,19 +240,6 @@ impl VoiceRegisters {
 #[repr(transparent)]
 pub struct PerVoiceFlag(u8);
 
-/// ADSR settings per voice, a 16-bit field.
-#[derive(Clone, Copy, Debug, Default)]
-#[repr(transparent)]
-pub struct AdsrSettings(u16);
-
-impl Deref for AdsrSettings {
-	type Target = u16;
-
-	fn deref(&self) -> &Self::Target {
-		&self.0
-	}
-}
-
 /// Global DSP flags in the FLG register.
 #[derive(Clone, Copy, Debug)]
 #[repr(transparent)]

sapemu/src/dsp/tables.rs

@@ -39,7 +39,7 @@ pub const GAUSS_TABLE: [u16; 512] = [
 ];
 
 /// Envelope rate table.
-pub const RATE_TABLE: [usize; 1 << 5] = [
+pub const RATE_TABLE: [u16; 1 << 5] = [
 	// Rate 0 is a sentinel value since it means no step is ever taken. This is handled elsewhere.
 	0, 2048, 1536, 1280, 1024, 768, 640, 512, 384, 320, 256, 192, 160, 128, 96, 80, 64, 48, 40, 32, 24, 20, 16, 12, 10,
 	8, 6, 5, 4, 3, 2, 1,

sapemu/src/memory.rs

@@ -62,7 +62,7 @@ impl Memory {
 	/// Performs a 16-bit little endian read from memory at the given address.
 	#[inline]
 	pub fn read_word(&mut self, address: u16, enable_boot_rom: bool) -> u16 {
-		u16::from(self.read(address, enable_boot_rom)) | (u16::from(self.read(address + 1, enable_boot_rom)) << 8)
+		u16::from_le_bytes([self.read(address, enable_boot_rom), self.read(address + 1, enable_boot_rom)])
 	}
 
 	/// Copies the state of the various memory mapped registers to the hidden memory behind it. This function is used

sapemu/src/smp.rs

@@ -97,6 +97,18 @@ pub const CPUIO3: u16 = 0x00F7;
 pub const DSPADDR: u16 = 0x00F2;
 /// DSP register address port.
 pub const DSPDATA: u16 = 0x00F3;
+/// Timer 0 divider.
+pub const T0DIV: u16 = 0x00FA;
+/// Timer 1 divider.
+pub const T1DIV: u16 = 0x00FB;
+/// Timer 2 divider.
+pub const T2DIV: u16 = 0x00FC;
+/// Timer 0 output.
+pub const T0OUT: u16 = 0x00FD;
+/// Timer 1 output.
+pub const T1OUT: u16 = 0x00FE;
+/// Timer 2 output.
+pub const T2OUT: u16 = 0x00FF;
 
 /// Vector for software interrupts.
 pub const BREAK_VECTOR: u16 = 0xFFDE;
@@ -255,6 +267,10 @@ impl Smp {
 			TEST => self.test_write(value),
 			CONTROL => self.control_write(value),
 			CPUIO0 | CPUIO1 | CPUIO2 | CPUIO3 => self.ports.write(address - CPUIO0, value),
+			T0DIV => self.timers.timer_divisor[0] = value,
+			T1DIV => self.timers.timer_divisor[1] = value,
+			T2DIV => self.timers.timer_divisor[2] = value,
+			// Writes to the timer output registers pass through to memory.
 			DSPDATA => {
 				let dsp_address = memory.read(DSPADDR, self.control.contains(ControlRegister::BootRomEnable));
 				dsp.write(dsp_address, value);
@@ -273,6 +289,12 @@ impl Smp {
 				let dsp_address = memory.read(DSPADDR, self.control.contains(ControlRegister::BootRomEnable));
 				dsp.read(dsp_address)
 			},
+			T0DIV => self.timers.timer_divisor[0],
+			T1DIV => self.timers.timer_divisor[1],
+			T2DIV => self.timers.timer_divisor[2],
+			T0OUT => self.timers.timer_out[0],
+			T1OUT => self.timers.timer_out[1],
+			T2OUT => self.timers.timer_out[2],
 			_ => memory.read(address, self.control.contains(ControlRegister::BootRomEnable)),
 		}
 	}

sapemu/src/smp/peripherals.rs

@@ -129,13 +129,13 @@ impl Timers {
 	const T2_RATE: usize = 64000;
 	const TIMER_CLOCKS_PER_STEP: [usize; 3] =
 		[Self::T01_CLOCKS_PER_STEP, Self::T01_CLOCKS_PER_STEP, Self::T2_CLOCKS_PER_STEP];
-	#[allow(unused)]
 	const TIMER_RATES: [usize; 3] = [Self::T01_RATE, Self::T01_RATE, Self::T2_RATE];
 
 	/// Create new timers.
 	#[must_use]
 	pub fn new() -> Self {
-		let mut new = Self { timer_out: [0; 3], timer_divisor: [1; 3], timer_tick_remaining: [0; 3] };
+		let mut new =
+			Self { timer_out: [0; 3], timer_divisor: [0xFF; 3], timer_tick_remaining: [0; 3] };
 		new.reset_timers_if_necessary();
 		new
 	}