From 2faa3e751230cbf1cb3bc374055ea7135c35656f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Magalh=C3=A3es?= <joamag@gmail.com>
Date: Mon, 24 Jul 2023 23:20:28 +0100
Subject: [PATCH] chore: audio support for libretro
---
frontends/libretro/src/lib.rs | 19 +++++++++++++++-
src/apu.rs | 41 ++++++++++++++++++++---------------
2 files changed, 41 insertions(+), 19 deletions(-)
diff --git a/frontends/libretro/src/lib.rs b/frontends/libretro/src/lib.rs
index d59c4bd0..202727ad 100644
--- a/frontends/libretro/src/lib.rs
+++ b/frontends/libretro/src/lib.rs
@@ -9,7 +9,7 @@ use std::{
};
use boytacean::{
- gb::GameBoy,
+ gb::{AudioProvider, GameBoy},
pad::PadKey,
ppu::{DISPLAY_HEIGHT, DISPLAY_WIDTH, RGB1555_SIZE},
rom::Cartridge,
@@ -288,6 +288,8 @@ pub extern "C" fn retro_set_controller_port_device() {
#[no_mangle]
pub extern "C" fn retro_run() {
let emulator = unsafe { EMULATOR.as_mut().unwrap() };
+ let sample_batch_cb = unsafe { AUDIO_SAMPLE_BATCH_CALLBACK.as_ref().unwrap() };
+ let channels = emulator.audio_channels();
let mut counter_cycles = 0_u32;
let cycle_limit = 4194304 / 60; //@TODO this is super tricky
@@ -304,6 +306,21 @@ pub extern "C" fn retro_run() {
// include the advance of both the CPU, PPU, APU
// and any other frequency based component of the system
counter_cycles += emulator.clock() as u32;
+
+ // obtains the audio buffer reference and queues it
+ // in a batch manner using the audio callback at the
+ // the end of the operation clears the buffer
+ let audio_buffer = emulator
+ .audio_buffer()
+ .iter()
+ .map(|v| *v as i16 * 256)
+ .collect::<Vec<i16>>();
+
+ sample_batch_cb(
+ audio_buffer.as_ptr(),
+ audio_buffer.len() / channels as usize,
+ );
+ emulator.clear_audio_buffer();
}
unsafe {
diff --git a/src/apu.rs b/src/apu.rs
index 367ad0ed..94906908 100644
--- a/src/apu.rs
+++ b/src/apu.rs
@@ -2,8 +2,6 @@ use std::collections::VecDeque;
use crate::{gb::GameBoy, warnln};
-const CHANNELS: u8 = 2;
-
const DUTY_TABLE: [[u8; 8]; 4] = [
[0, 0, 0, 0, 0, 0, 0, 1],
[1, 0, 0, 0, 0, 0, 0, 1],
@@ -93,9 +91,22 @@ pub struct Apu {
ch3_out_enabled: bool,
ch4_out_enabled: bool,
+ /// The RAM that is used to sore the wave information
+ /// to be used in channel 3 audio
wave_ram: [u8; 16],
+ /// The rate at which audio samples are going to be
+ /// taken, ideally this value should be aligned with
+ /// the sampling rate of the output device. A typical
+ /// sampling rate would be of 44.1kHz.
sampling_rate: u16,
+
+ /// The number of audion channels that are going to be
+ /// outputted as part fo the audio buffer)
+ channels: u8,
+
+ /// Internal sequencer counter that runs at 512Hz
+ /// used for the activation of the tick actions.
sequencer: u16,
sequencer_step: u8,
output_timer: i16,
@@ -106,7 +117,7 @@ pub struct Apu {
}
impl Apu {
- pub fn new(sampling_rate: u16, buffer_size: f32, clock_freq: u32) -> Self {
+ pub fn new(sampling_rate: u16, channels: u8, buffer_size: f32, clock_freq: u32) -> Self {
Self {
ch1_timer: 0,
ch1_sequence: 0,
@@ -180,25 +191,18 @@ impl Apu {
ch3_out_enabled: true,
ch4_out_enabled: true,
- /// The RAM that is used to sore the wave information
- /// to be used in channel 3 audio
wave_ram: [0u8; 16],
- /// The rate at which audio samples are going to be
- /// taken, ideally this value should be aligned with
- /// the sampling rate of the output device. A typical
- /// sampling rate would be of 44.1kHz.
sampling_rate,
+ channels,
- /// Internal sequencer counter that runs at 512Hz
- /// used for the activation of the tick actions.
sequencer: 0,
sequencer_step: 0,
output_timer: 0,
audio_buffer: VecDeque::with_capacity(
- (sampling_rate as f32 * buffer_size) as usize * CHANNELS as usize,
+ (sampling_rate as f32 * buffer_size) as usize * channels as usize,
),
- audio_buffer_max: (sampling_rate as f32 * buffer_size) as usize * CHANNELS as usize,
+ audio_buffer_max: (sampling_rate as f32 * buffer_size) as usize * channels as usize,
clock_freq,
}
}
@@ -324,13 +328,14 @@ impl Apu {
// the buffer (avoiding overflow) and then then the new audio
// volume item is added to the queue
if self.audio_buffer.len() >= self.audio_buffer_max {
- self.audio_buffer.pop_front();
- self.audio_buffer.pop_front();
+ for _ in 0..self.channels {
+ self.audio_buffer.pop_front();
+ }
}
if self.left_enabled {
self.audio_buffer.push_back(self.output());
}
- if self.right_enabled {
+ if self.right_enabled && self.channels > 1 {
self.audio_buffer.push_back(self.output());
}
@@ -729,7 +734,7 @@ impl Apu {
}
pub fn channels(&self) -> u8 {
- CHANNELS
+ self.channels
}
pub fn audio_buffer(&self) -> &VecDeque<u8> {
@@ -1061,7 +1066,7 @@ impl Apu {
impl Default for Apu {
fn default() -> Self {
- Self::new(44100, 1.0, GameBoy::CPU_FREQ)
+ Self::new(44100, 2, 1.0, GameBoy::CPU_FREQ)
}
}
--
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