82 lines
2.3 KiB
C++
82 lines
2.3 KiB
C++
/*
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* audio.h
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* MontaukOS 2D Game Engine - Audio System
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* Wraps MontaukOS audio syscalls for game sound playback
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* Copyright (c) 2026 Daniel Hammer
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*/
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#pragma once
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#include <cstdint>
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#include <montauk/syscall.h>
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namespace engine {
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static constexpr int AUDIO_SAMPLE_RATE = 44100;
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static constexpr int AUDIO_CHANNELS = 2;
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static constexpr int AUDIO_BITS = 16;
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struct AudioEngine {
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int handle = -1;
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int volume = 80;
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bool init() {
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handle = montauk::audio_open(AUDIO_SAMPLE_RATE, AUDIO_CHANNELS, AUDIO_BITS);
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if (handle < 0) return false;
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montauk::audio_set_volume(handle, volume);
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return true;
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}
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void shutdown() {
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if (handle >= 0) {
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montauk::audio_close(handle);
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handle = -1;
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}
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}
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void set_volume(int percent) {
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volume = percent;
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if (handle >= 0)
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montauk::audio_set_volume(handle, volume);
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}
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// Write raw PCM samples to the audio device.
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// data: signed 16-bit stereo PCM samples
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// size: number of bytes
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bool write_pcm(const void* data, uint32_t size) {
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if (handle < 0) return false;
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return montauk::audio_write(handle, data, size) >= 0;
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}
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// Generate and play a simple tone (square wave) for duration_ms.
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// Useful for basic sound effects. Non-blocking (writes samples to buffer).
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void play_tone(int freq_hz, int duration_ms, int tone_volume = 50) {
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if (handle < 0 || freq_hz <= 0) return;
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int total_samples = (AUDIO_SAMPLE_RATE * duration_ms) / 1000;
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int half_period = AUDIO_SAMPLE_RATE / (2 * freq_hz);
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if (half_period <= 0) half_period = 1;
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int16_t amp = (int16_t)(327 * tone_volume / 100); // ~1% of max
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static constexpr int CHUNK = 512;
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int16_t buf[CHUNK * 2]; // stereo
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int written = 0;
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while (written < total_samples) {
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int n = total_samples - written;
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if (n > CHUNK) n = CHUNK;
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for (int i = 0; i < n; i++) {
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int sample_pos = written + i;
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int16_t val = ((sample_pos / half_period) % 2 == 0) ? amp : -amp;
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buf[i * 2] = val;
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buf[i * 2 + 1] = val;
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}
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montauk::audio_write(handle, buf, n * 4);
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written += n;
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}
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}
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};
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} // namespace engine
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