simple filebrowser for 3ds

common.h

#pragma once

#include <3ds.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdbool.h>

// according to wikipedia, the max FAT32 path length is 255 UTF-16 characters, so 0xFF * 2 (because the 16 in UTF-16 means 16 bits = 2 bytes) (shifting left of 1 is the same as multiplying by 2)
#define MAX_PATH_LEN (0xFF << 1)

typedef struct {
	char name[MAX_PATH_LEN+1];
	bool isFile;
} dirInfo;

dir.c

#include <dirent.h>
#include "dir.h"

int listdir(char * path, dirInfo * dirInfoArray)
{
	DIR *dir;
	struct dirent *ent;
	int count = 0;
	
	if ((dir = opendir(path)) != NULL) {
		while ((ent = readdir(dir)) != NULL) {
			strcpy(dirInfoArray[count].name, ent->d_name);
			dirInfoArray[count].isFile = (ent->d_type == 8);
			count++;
		}
		closedir (dir);
	}
	
	return count;
}

dir.h

#include "common.h"

int listdir(char * path, dirInfo * dirInfoArray);

draw.c

#include "draw.h"

//width in characters of the screen you're drawing on. 50 for the top screen, 40 for bottom
#define SCREEN_WIDTH 50

#define OFFSET 1 //offset in characters of the file list from the location bar

#define MAX_ENTRIES_PER_SCREEN (SCREEN_WIDTH-1-OFFSET*2)

static int scroll = 0;

static char uparrow[] = {30, 0};
static char downarrow[] = {31, 0};

void drawDirList(dirInfo * dirInfoArray, char * currentPath, int currentDir, int dirCount)
{
	consoleClear();
	if (strlen(currentPath) <= SCREEN_WIDTH) printf("\x1b[0;0H\x1b[47;30m%s\x1b[0m", currentPath);
	else printf("\x1b[0;0H\x1b[47;30m...%s\x1b[0m", &currentPath[strlen(currentPath)-SCREEN_WIDTH+3]);
	
	if (currentDir == 0) {
		scroll = 0;
	}
	else if ((dirCount > MAX_ENTRIES_PER_SCREEN) && (currentDir == dirCount-1)) {
		scroll = dirCount - MAX_ENTRIES_PER_SCREEN;
	}
	else if (currentDir >= (MAX_ENTRIES_PER_SCREEN + scroll)) {
		scroll++;
	}
	else if ((currentDir - scroll) < 0) {
		scroll--;
	}
	
	if (scroll != 0) printf("\x1b[%i;0H%s", OFFSET+1, uparrow);
	
	if ((dirCount > MAX_ENTRIES_PER_SCREEN) && scroll != (dirCount - MAX_ENTRIES_PER_SCREEN)) printf("\x1b[%i;0H%s", MAX_ENTRIES_PER_SCREEN+OFFSET, downarrow);
	
	for (int i = scroll; (i-scroll) < MAX_ENTRIES_PER_SCREEN; i++) {
		//selected dir has white background, others have black
		int bgcolor = (i == currentDir) ? 47 : 40;
		//if it's a file, it has a blue name. otherwise, reverse of background
		int txtcolor = (dirInfoArray[i].isFile) ? 36 : ((i == currentDir) ? 30 : 37);
		if (dirInfoArray[i].name != NULL) printf("\x1b[%i;2H\x1b[%i;%im%s\x1b[0m", i+OFFSET+1-scroll, bgcolor, txtcolor, dirInfoArray[i].name);
	}
}

draw.h

#include "common.h"

void drawDirList(dirInfo * dirInfoArray, char * currentPath, int currentDir, int dirCount);

main.c

#include "common.h"
#include "dir.h"
#include "draw.h"
#include "sort.h"

static char currentPath[MAX_PATH_LEN+1]; //for the ending nullbyte

static dirInfo dirInfoArray[256];
static int dirCount = 0;
static int currentDir = 0;

int main() {
	gfxInitDefault();
	
	consoleInit(GFX_TOP, NULL);
	
	chdir("/");
	
	goto change;
	
	while (aptMainLoop()) {
		
		if (false) { //things in there will only run if you do a goto, otherwise the screen would flicker because of constantly clearing
			change:
			currentDir = 0;
			getcwd(currentPath, MAX_PATH_LEN+1);
			dirCount = listdir(currentPath, dirInfoArray);
			for (int i = dirCount; i < 256; i++) {
				dirInfoArray[i].name[0] = 0;
				dirInfoArray[i].isFile = false;
			}
			sortDirList(dirInfoArray, dirCount);
			
			draw:
			if (currentDir > dirCount-1) currentDir = dirCount-1;
			if (currentDir < 0) currentDir = 0;
			drawDirList(dirInfoArray, currentPath, currentDir, dirCount);
			gfxFlushBuffers();
			gfxSwapBuffers();
			gspWaitForVBlank();
		}
		
		hidScanInput();
		
		if (hidKeysDown() & KEY_START) {
			break;
		}
		else if (hidKeysDown() & KEY_A) {
			if (dirCount != 0) {
				if (dirInfoArray[currentDir].isFile) {
					//do stuff with file
				}
				else {
					chdir(dirInfoArray[currentDir].name);
					goto change;
				}
			}
		}
		else if (hidKeysDown() & KEY_B) {
			chdir("..");
			goto change;
		}
		else if (hidKeysDown() & KEY_LEFT) {
			currentDir = 0;
			goto draw;
		}
		else if (hidKeysDown() & KEY_RIGHT) {
			currentDir = dirCount-1;
			goto draw;
		}
		else if (hidKeysDown() & KEY_UP) {
			currentDir--;
			goto draw;
		}
		else if (hidKeysDown() & KEY_DOWN) {
			currentDir++;
			goto draw;
		}
		
		gfxFlushBuffers();
		gfxSwapBuffers();
		gspWaitForVBlank();
	}
	
	gfxExit();
	return 0;
}

sort.c

#include "sort.h"

int checkSorted(const void * a, const void * b)
{
	dirInfo * entryA = (dirInfo *)a;
	dirInfo * entryB = (dirInfo *)b;

	if ((entryA->isFile && entryB->isFile) || (!entryA->isFile && !entryB->isFile)) {
		return strcmp(entryA->name, entryB->name);
	}
	else if (entryA->isFile) {
        return 1;
	}
	else if (entryB->isFile) {
        return -1;
	}

	return 0;
}

void sortDirList(dirInfo * dirInfoArrayArray, int dirCount)
{
	qsort(dirInfoArrayArray, dirCount, sizeof(dirInfo), &checkSorted);
}

sort.h

#include "common.h"

void sortDirList(dirInfo * dirInfoArrayArray, int dirCount);