sdmc/source/main.c

///////////////////////////////////////
//           SDMC example            //
///////////////////////////////////////
 
//this example shows you how to load a binary image file from the SD card and display it on the lower screen
//for this to work you should copy test.bin to same folder as your .3dsx
//this file was generated with GIMP by saving a 240x320 image to raw RGB
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
 
#include <3ds.h>
#include "costable.h"
 
//this will contain the data read from SDMC
u8* buffer;
 
//3DS has VFPs so we could just use cos
//but we're old school so LUT4life
s32 pcCos(u16 v)
{
    return costable[v&0x1FF];
}
 
void renderEffect()
{
    static int cnt;
    u8* bufAdr=gfxGetFramebuffer(GFX_TOP, GFX_LEFT, NULL, NULL);
 
    int i, j;
    for(i=1;i<400;i++)
    {
        for(j=1;j<240;j++)
        {
            u32 v=(j+i*240)*3;
            bufAdr[v]=(pcCos(i+cnt)+4096)/32;
            bufAdr[v+1]=(pcCos(j-256+cnt)+4096)/64;
            bufAdr[v+2]=(pcCos(i+128-cnt)+4096)/32;
        }
    }
 
    cnt++;
}
 
int main(int argc, char** argv)
{
 
    gfxInitDefault(); //makes displaying to screen easier
 
    FILE *file = fopen("test.bin","rb");
    if (file == NULL) goto exit;
 
    // seek to end of file
    fseek(file,0,SEEK_END);
 
    // file pointer tells us the size
    off_t size = ftell(file);
 
    // seek back to start
    fseek(file,0,SEEK_SET);
 
    //allocate a buffer
    buffer=malloc(size);
    if(!buffer)goto exit;
 
    //read contents !
    off_t bytesRead = fread(buffer,1,size,file);
 
    //close the file because we like being nice and tidy
    fclose(file);
 
    if(size!=bytesRead)goto exit;
 
    while(aptMainLoop())
    {
        //exit when user hits B
        hidScanInput();
        if(keysHeld()&KEY_B)break;
 
        //render rainbow
        renderEffect();
 
        //copy buffer to lower screen (don't have to do it every frame)
        memcpy(gfxGetFramebuffer(GFX_BOTTOM, GFX_BOTTOM, NULL, NULL), buffer, size);
 
        //wait & swap
        gfxSwapBuffersGpu();
        gspWaitForEvent(GSPGPU_EVENT_VBlank0, false);
    }
 
    //cleanup and return
    //returning from main() returns to hbmenu when run under ninjhax
    exit:
 
    //closing all services even more so
    gfxExit();
    return 0;
}