audio/streaming/source/main.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
 
#include <3ds.h>
 
#define SAMPLERATE 22050
#define SAMPLESPERBUF (SAMPLERATE / 30)
#define BYTESPERSAMPLE 4
 
//----------------------------------------------------------------------------
void fill_buffer(void *audioBuffer,size_t offset, size_t size, int frequency ) {
//----------------------------------------------------------------------------
 
    u32 *dest = (u32*)audioBuffer;
 
    for (int i=0; i<size; i++) {
 
        s16 sample = INT16_MAX * sin(frequency*(2*M_PI)*(offset+i)/SAMPLERATE);
 
        dest[i] = (sample<<16) | (sample & 0xffff);
    }
 
    DSP_FlushDataCache(audioBuffer,size);
 
}
 
//----------------------------------------------------------------------------
int main(int argc, char **argv) {
//----------------------------------------------------------------------------
 
    PrintConsole topScreen;
    ndspWaveBuf waveBuf[2];
 
    gfxInitDefault();
 
    consoleInit(GFX_TOP, &topScreen);
 
    consoleSelect(&topScreen);
 
    printf("libctru streaming audio\n");
 
    u32 *audioBuffer = (u32*)linearAlloc(SAMPLESPERBUF*BYTESPERSAMPLE*2);
 
    bool fillBlock = false;
 
    ndspInit();
 
    ndspSetOutputMode(NDSP_OUTPUT_STEREO);
 
    ndspChnSetInterp(0, NDSP_INTERP_LINEAR);
    ndspChnSetRate(0, SAMPLERATE);
    ndspChnSetFormat(0, NDSP_FORMAT_STEREO_PCM16);
 
    float mix[12];
    memset(mix, 0, sizeof(mix));
    mix[0] = 1.0;
    mix[1] = 1.0;
    ndspChnSetMix(0, mix);
 
    int notefreq[] = {
        262, 294, 339, 349, 392, 440,
        494, 440, 392, 349, 339, 294
    };
 
    int note = 4;
 
    memset(waveBuf,0,sizeof(waveBuf));
    waveBuf[0].data_vaddr = &audioBuffer[0];
    waveBuf[0].nsamples = SAMPLESPERBUF;
    waveBuf[1].data_vaddr = &audioBuffer[SAMPLESPERBUF];
    waveBuf[1].nsamples = SAMPLESPERBUF;
 
    size_t stream_offset = 0;
 
    fill_buffer(audioBuffer,stream_offset, SAMPLESPERBUF * 2, notefreq[note]);
 
    stream_offset += SAMPLESPERBUF;
 
    ndspChnWaveBufAdd(0, &waveBuf[0]);
    ndspChnWaveBufAdd(0, &waveBuf[1]);
 
    printf("Press up/down to change tone\n");
 
    while(aptMainLoop()) {
 
        gfxSwapBuffers();
        gfxFlushBuffers();
        gspWaitForVBlank();
 
        hidScanInput();
        u32 kDown = hidKeysDown();
 
        if (kDown & KEY_START)
            break; // break in order to return to hbmenu
 
        if (kDown & KEY_DOWN) {
            note -= 1;
 
            if (note<0) note = sizeof(notefreq)/sizeof(notefreq[0])-1;
        }
 
        if (kDown & KEY_UP) {
            note += 1;
 
            if (note > (sizeof(notefreq)/sizeof(notefreq[0])-1)) note = 0;
        }
 
        if (waveBuf[fillBlock].status == NDSP_WBUF_DONE) {
 
            fill_buffer(waveBuf[fillBlock].data_pcm16, stream_offset, waveBuf[fillBlock].nsamples,notefreq[note]);
 
            ndspChnWaveBufAdd(0, &waveBuf[fillBlock]);
            stream_offset += waveBuf[fillBlock].nsamples;
 
            fillBlock = !fillBlock;
        }
    }
 
    ndspExit();
 
    linearFree(audioBuffer);
 
    gfxExit();
    return 0;
}