audio/micrecord/source/micrecord.c

#include <nds.h>
#include <stdio.h>

//the record sample rate
#define sample_rate  8000

//buffer to hold sound data for playback
u16* sound_buffer = 0;

//buffer which is written to by the arm7
u16* mic_buffer = 0;

//the length of the current data
u32 data_length = 0;

//enough hold 5 seconds of 16bit audio
u32 sound_buffer_size = sample_rate * 2 * 5;

//the mic buffer sent to the arm7 is a double buffer
//every time it is half full the arm7 signals us so we can read the
//data.  I want the buffer to swap about once per frame so i chose a
//buffer size large enough to hold two frames of 16bit mic data
u32 mic_buffer_size = sample_rate * 2 / 30;


//mic stream handler
void micHandler(void* data, int length)
{
        if(!sound_buffer || data_length > sound_buffer_size) return;
        
        
        DC_InvalidateRange(data, length);

        dmaCopy(data, ((u8*)sound_buffer) + data_length, length);
        
        data_length += length;

        iprintf(".");
        
}

void record(void)
{
        data_length = 0;
        soundMicRecord(mic_buffer, mic_buffer_size, MicFormat_12Bit, sample_rate, micHandler);
}

void play(void)
{
        soundMicOff();
        soundEnable();
        iprintf("data length: %i\n", data_length);
        soundPlaySample(sound_buffer, SoundFormat_16Bit, data_length, sample_rate, 127, 64, false, 0);
}

int main(void) 
{
        int key;
        bool recording = false;

        sound_buffer = (u16*)malloc(sound_buffer_size);
        mic_buffer = (u16*)malloc(mic_buffer_size);

        consoleDemoInit();

        iprintf("Press A to record / play\n");

        while(1) 
        {

                scanKeys();
                key = keysDown();

                if(key & KEY_A)
                {
                        recording ? play() : record();
                        recording = !recording;
                        iprintf("%s\n", recording ? "recording" : "playing");
                }

                swiWaitForVBlank();

        }
}