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reading from sd

Posted by trottolo

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trottolo

reading from sd
April 07, 2009 03:59PM

Registered: 15 years ago
Posts: 24

hello guys...
I have another request....is there any library could hrl reading from sd slot?

thx
Amedeo

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daniel_c_w

Re: reading from sd
April 07, 2009 04:08PM

Registered: 15 years ago
Posts: 1,012

hrl?

:D

Edited 1 time(s). Last edit at 04/07/2009 04:08PM by daniel_c_w.

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trottolo

Re: reading from sd
April 07, 2009 07:44PM

Registered: 15 years ago
Posts: 24

hrl= help ...but I don't know why I wrote that....

Edited 1 time(s). Last edit at 04/07/2009 07:46PM by trottolo.

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cdmac

Re: reading from sd
April 07, 2009 08:01PM

Registered: 15 years ago
Posts: 9

libfat, which is installed as part of devkitpro.

#include fat.h // Should have angle brackets but this forum doesn't display them
...
fatInitDefault();
fatMountSimple("sd", &__io_wiisd);

From then on you can access files on the SD card by just using the regular C file operations. Just add sd:/ (or whatever you mounted the drive with) to the beginning of your path name.

Oh yeah, you have to link with -lfat too, and I found the order important. I have mine declared at the beginning of my library list, after -ldb.

Thanks,
cdmac

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trottolo

Re: reading from sd
April 08, 2009 08:23AM

Registered: 15 years ago
Posts: 24

thx for reply...could you add the code of your test software?

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scanff

Re: reading from sd
April 08, 2009 08:36AM

Registered: 15 years ago
Posts: 703

If you're just wanting to read a file then...


fatInitDefault();

FILE* f;
char buf[50] = {0};

f = fopen("/hello.txt","r"); // will be root of the SD
fread(buf,50,1,f);
fclose(f);

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Tantric

Re: reading from sd
April 08, 2009 08:50PM

Registered: 15 years ago
Posts: 441

Quote
cdmac
libfat, which is installed as part of devkitpro.

#include fat.h // Should have angle brackets but this forum doesn't display them
...
fatInitDefault();
fatMountSimple("sd", &__io_wiisd);

fatMountSimple("sd", &__io_wiisd); is not required - this is done by fatInitDefault()

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Tantric

Re: reading from sd
April 08, 2009 08:51PM

Registered: 15 years ago
Posts: 441

Quote
scanff
If you're just wanting to read a file then...


fatInitDefault();

FILE* f;
char buf[50] = {0};

f = fopen("/hello.txt","r"); // will be root of the SD
fread(buf,50,1,f);
fclose(f);

Actually, that might not be the root of the SD. Depends on if SD was mounted and set as the default devoptab device. It'd be best to do this instead:

f = fopen("sd:/hello.txt","r"); // will be root of the SD

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Tantric

Re: reading from sd
April 08, 2009 08:59PM

Registered: 15 years ago
Posts: 441

Here's a better example:


fatInitDefault(); // should only be called once

// will read in the whole file

char * buffer; // file buffer
int size = 0; // file size
FILE* file = fopen("sd:/hello.txt","rb");

if(file > 0)
{
	struct stat fileinfo;
	fstat(file->_file, &fileinfo);
	size = fileinfo.st_size;	
	buffer = (char *)malloc(size);
	fread(buffer, 1, size, file);
	fclose(file);
}

// call this when you're done with the file data
free(buffer);

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trottolo

Re: reading from sd
April 11, 2009 01:04PM

Registered: 15 years ago
Posts: 24

Quote
Tantric
Here's a better example:
This was what I was looking for...perfect example!!!


fatInitDefault(); // should only be called once

// will read in the whole file

char * buffer; // file buffer
int size = 0; // file size
FILE* file = fopen("sd:/hello.txt","rb");

if(file > 0)
{
	struct stat fileinfo;
	fstat(file->_file, &fileinfo);
	size = fileinfo.st_size;	
	buffer = (char *)malloc(size);
	fread(buffer, 1, size, file);
	fclose(file);
}

// call this when you're done with the file data
free(buffer);

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csanii

Code Dump???
April 17, 2009 03:17AM

Registered: 15 years ago
Posts: 8

I am not sure what is wrong with this code....
It compiles with no issues but when I run it I just get a Code Dump.
There are arrows around the include names but the forum doesn't show them.

#include stdio.h
#include fat.h
....
char buffer[20] = {0};
FILE* fp;

fatInitDefault();
fp=fopen("sd:/gamefile.dat","rb");
fread(buffer, 20, 1, fp);
printf("%s\n",buffer);
fclose(fp);

Anyone see the problem?

My makefile has the following:
LIBS := -lfat -lwiiuse -lbte -logc -lm
Does the order matter? Am i missing a library?
There are no compile or linking error messages.

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scanff

Re: reading from sd
April 17, 2009 06:20AM

Registered: 15 years ago
Posts: 703

I can't see a problem. Looks like you have the correct libs.

Maybe your buffer[20] is not big enough. You could always put a NULL check on the file to ensure it's actually opening the file.

FILE* fp = 0;
fp=fopen("sd:/gamefile.dat","rb");
if(!fp) exit(0);

Also don't forget in the printf("%s\n",buffer); your buffer is treated as text and needs to be NULL terminated. So if you're reading 20 bytes from the file then your buffer should be buffer[21] = {0} otherwise the printf will overrun the buffer.

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csanii

Re: reading from sd
April 17, 2009 11:30PM

Registered: 15 years ago
Posts: 8

Well sure enough, it is not opening my file so when I try to read the file I get a Code Dump.

But as to why it can't open the file, I don't know. The code looks right....
I put the file on the root of the SD card. File has the right name.
I even put a copy of the file in the same directory as my application just in case it wasn't looking in the root dir.
Still no luck.

*******************************
PROBLEM SOLVED!!!!!

1) If I use "sd:/filename" it does NOT work but if I use just plain "filename" it does work
2) SDHC does not work but a plain SD card does - this now explains why on some of the Homebrew I get a Core Dump

I updated my DEVKITPRO to the latest and recompiled and now SDHC WORKS!!!!!

Edited 2 time(s). Last edit at 04/19/2009 02:30PM by csanii.

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CloneDeath

Re: reading from sd
July 01, 2009 12:10AM

Registered: 14 years ago
Posts: 42

Arg, I keep getting a code dump I need help @_@

It compiles fine, and I included the lib.

It works fine until I press A, then it just barfs all over my screen, with the whole DSI exception, Stack Dump, and Code Dump :P

Here is the two functions that I use:

#include 
#include 
#include 
#include 
#include 
#include "FileIO.h"

namespace FileIO{
 
	void InitFat(){
		//__io_wiisd.startup();
		//fatMountSimple("sd", &__io_wiisd);
		fatInitDefault();
		fatMountSimple("sd", &__io_wiisd);
	}
	
//This is the function it crashes on...
	void SDTest(){
		FILE* test;
		test = fopen("sd:/test.txt", "rw");
		fprintf(test, "Hello World!\n");
		fclose(test);
	}
}

I call InitFat once then run the SDTest and it crashes there.

I get all the complicated stuff for the game done, but I can't figure out simple saving and loading #_#

P.S. I know the code is bad, but I just want this to work so I could start making the actual saving and loading system.

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CloneDeath

Re: reading from sd
July 01, 2009 12:37AM

Registered: 14 years ago
Posts: 42

figured it out -_-

so aparently "fatMountSimple("sd", &__io_wiisd);" just doesn't work o.O

anyhow, here is the working code:

#include 
#include 
#include 
#include 
#include 
#include "FileIO.h"

namespace FileIO{
 
	void InitFat(){
		//__io_wiisd.startup();
		//fatMountSimple("sd", &__io_wiisd);
		fatInitDefault();
		//fatMountSimple("sd", &__io_wiisd);
	}
	
	void SDTest(){
		FILE* test;
		test = fopen("test.txt", "w");
		fprintf(test, "Hello World!\n");
		fclose(test);
	}
}

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WiiPower

Re: reading from sd
July 02, 2009 08:46AM

Registered: 14 years ago
Posts: 59

I use:
#include sdcard/wiisd_io.h

And:
__io_wiisd.startup();
fatMountSimple("sd", &__io_wiisd);
to mount the sd card

and:
fatUnmount("sd");
__io_wiisd.shutdown();
to unmount it again.

If you do IOS Reloads or want to change the sd card inside the program you need the unmount. Also i prefer fatmountsimple because it only touches the sd card, while fatinitdefault inits ALL storage devices it finds, if you have an usb pen connected at the same time, it gets initialised too.

I never got any code dumps because of this code, and also you can accesss all files with "sd:/filename" without problems, or change "sd" to "fat" for example if you use both sd and usb, just not at the same time, and want to use the same filenames for both.

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ekeeke

Re: reading from sd
July 02, 2009 09:59AM

Registered: 15 years ago
Posts: 276

fatMountSimple, fatMount and fatUnmount automatically handle device startup() and shutdown() functions, there shouldn't be any need for you to call them twice.

Another interest of fatInitDefault is to set the first detected FAT device as default IO device so that you can simply access files without specifying "sd:" or "usb:". By the way, I don't think "fat:" is supported anymore with the current interfaces.

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WiiPower

Re: reading from sd
July 02, 2009 12:25PM

Registered: 14 years ago
Posts: 59

Was that always there? Thanks for the hint.

You can still use "fat" if you want. I use that for example in my Gecko OS mod that loads Ocarina from sd and usb. Only if you use fatinitdefault, you can't use "fat" anymore, and i already told why i don't recommend using fatinitdefault.