AVRGameboy/audio.c at dev · harishun/AVRGameboy · GitHub

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// audio.c — see audio.h for the module overview.

#include "audio.h"
#include "system.h"

static const Note *s_sequence    = 0;
static uint8_t      s_sequenceLen = 0;
static uint8_t      s_index       = 0;
static uint32_t      s_noteStartMs = 0;
static bool          s_playing     = false;

static Note s_singleNoteBuf[1]; // backing storage for audioPlayTone()

static void StartNote(uint8_t index, uint32_t nowMs) {
    s_index       = index;
    s_noteStartMs = nowMs;
    systemAudioSetFrequency(s_sequence[index].freqHz);
}

void audioInit(void) {
    systemAudioInit();
}

void audioSetVolume(uint8_t vol) {
    systemAudioSetVolume(vol);
}

void audioPlayTone(uint16_t freqHz, uint16_t durationMs) {
    s_singleNoteBuf[0].freqHz     = freqHz;
    s_singleNoteBuf[0].durationMs = durationMs;
    audioPlaySequence(s_singleNoteBuf, 1);
}

void audioPlaySequence(const Note *notes, uint8_t count) {
    if (count == 0) {
        audioStop();
        return;
    }
    s_sequence    = notes;
    s_sequenceLen = count;
    s_playing     = true;
    StartNote(0, systemGetTimeMs());
}

void audioUpdate(uint32_t nowMs) {
    if (!s_playing) return;

    if (nowMs < s_noteStartMs) return;

    if ((nowMs - s_noteStartMs) >= s_sequence[s_index].durationMs) {
        uint8_t next = (uint8_t)(s_index + 1);
        if (next >= s_sequenceLen) {
            audioStop();
        } else {
            StartNote(next, s_noteStartMs + s_sequence[s_index].durationMs);
        }
    }
}

void audioStop(void) {
    s_playing     = false;
    s_sequence    = 0;
    s_sequenceLen = 0;
    systemAudioStop();
}

bool audioIsPlaying(void) {
    return s_playing;
}

void audioPlaySfxMenuMove(void) {
    static const Note sfx[] = { {880, 40} };
    audioPlaySequence(sfx, 1);
}

void audioPlaySfxMenuSelect(void) {
    static const Note sfx[] = { {659, 50}, {988, 80} };
    audioPlaySequence(sfx, 2);
}

void audioPlaySfxGameOver(void) {
    static const Note sfx[] = {
        {440, 150},
        {415, 150},
        {392, 150},
        {370, 400}
    };
    audioPlaySequence(sfx, 4);
}

void audioPlaySfxHighScore(void) {
    static const Note sfx[] = {
        {523, 100}, // C5
        {659, 100}, // E5
        {784, 100}, // G5
        {1046, 200}, // C6
        {1046, 200}  // C6 (repeat)
    };
    audioPlaySequence(sfx, 5);
}