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;
}