C/C++ Programming Help Thread

[Auraomega]

I havn't got access to my codes at the moment, but I was wondering if it was possible to store the data of the screen display buffer in memory using the graphics.c...

I want to make a function that will read the current thing on screen, and store it away for use later, I thought it would be as simple as just using getVramDisplayBuffer but I realised this only returns a pointer, and that the display buffer constantly changing means the data is changed too, I need to keep that data, I was thinking about using malloc to make the memory, but I'm not sure off the top of my head what arguments to use, so if anyone knows how to do this (or an easier way) I'd love to hear it :)

Sorry if I explained that badly, or just rambled, I just hope I got my question across properly.

Also, has anyone got an code showing how to mount flash2 as read/write as I can't find the arguments required, I assumed flash2 but it returned the nodev error, I also tried assigning it incase it wasn't already assigned, again no luck, so any pointers on this would be aprechiated.

-Aura

[Grimfate126]

I havn't got access to my codes at the moment, but I was wondering if it was possible to store the data of the screen display buffer in memory using the graphics.c...

I want to make a function that will read the current thing on screen, and store it away for use later, I thought it would be as simple as just using getVramDisplayBuffer but I realised this only returns a pointer, and that the display buffer constantly changing means the data is changed too, I need to keep that data, I was thinking about using malloc to make the memory, but I'm not sure off the top of my head what arguments to use, so if anyone knows how to do this (or an easier way) I'd love to hear it :)

Sorry if I explained that badly, or just rambled, I just hope I got my question across properly.

Also, has anyone got an code showing how to mount flash2 as read/write as I can't find the arguments required, I assumed flash2 but it returned the nodev error, I also tried assigning it incase it wasn't already assigned, again no luck, so any pointers on this would be aprechiated.

-Aura

i havent done much about screen buffers, but this would be my guess:

1. Get the pointer.
2. malloc(sizeof(*pointer)); // Dont know if this would work exactly //
3. memcpy(from pointer to malloc'd memory);

[tommydanger]

haven't tested it but this should do it aswell

u32 buffer[512x272] //buffer to store whole screenbuffer
memcpy(buffer,0x04000000, 512*272) //copy framebuffer content to buffer
//done

[Judas]

haven't tested it but this should do it aswell

The screen is only 480*272. Any reason why you chose 512 instead of 480?

[Auraomega]

The screen is only 480*272. Any reason why you chose 512 instead of 480?

I'm back :)

Actually, you are both wrong, it should be 512*272*4...

#define FRAMEBUFFER_SIZE (PSP_LINE_SIZE*SCREEN_HEIGHT*4)

I'm crashing at the moment using the codes posted above, I'm not sure if its the memory constraint or not, I'll work at it a little more, if it still crashes I'll post the code and see if anyone else can see what I'm doing wrong (if anything).

-Aura

[Raphael]

I'm back :)

Actually, you are both wrong, it should be 512*272*4...

#define FRAMEBUFFER_SIZE (PSP_LINE_SIZE*SCREEN_HEIGHT*4)

No. Tommydanger was right (apart from the memcpy's last parameter). He created an array of u32s, so the size was in fact 512*272*4. Anyway, it crashes, because the buffer is created on stack and the stack is not large enough for that. Either make the declaration static or use malloc.
Also, you could get weird results if you're reading back the framebuffer while it is currently being rendered too. So you'd probably be best off mutexing the memcpy or disabling interrupts during the time and make sure it happens after the rendering of the screen has finished (by hooking sceDisplaySetFramebuf or sceGuSync).

[BigSanFrey]

Anyway i have a problem. My "game" is meant to show 4 little squares with a cross in it (this is the picture ). But number four does not show, it shows if i have the

    int StarX4 = GetRandomNum(331, 416);
    int StarY4 = GetRandomNum(1, 272);

set to

    int StarX4 = GetRandomNum(3, 40)
    int StarY4 = GetRandomNum(1, 272);

Or if i collect star number 2 :Argh:...

Here is my code (in a spoiler)

Spoiler for Code:

int main(void) {
    SetupCallbacks();
    initGraphics();
    SceCtrlData pad;
    int ok = 1;
    int x0 = 100;
    int y0 = 100;
    int x0Height = 10;
    int x0Width = 10;

	// Load background
    Image* Background;
    Background = loadImage("./Images/Background.png");
	// Load face
    Image* Face;
    Face = loadImage("./Images/face.png");
	// Load square
    Image* Square1;
    Square1 = loadImage("./Images/1.png");
	// Load square
    Image* Square2;
    Square2 = loadImage("./Images/2.png");
	// Load square
    Image* Square3;
    Square3 = loadImage("./Images/3.png");
	// Load square
    Image* Square4;
    Square4 = loadImage("./Images/4.png");
	// Load wall
    Image* Wall;
    Wall = loadImage("./Images/spr_wall.png");

    int StarX1 = GetRandomNum(1, 110);
    int StarY1 = GetRandomNum(1, 272);

    int StarX2 = GetRandomNum(111, 220);
    int StarY2 = GetRandomNum(1, 272);

    int StarX3 = GetRandomNum(221, 330);
    int StarY3 = GetRandomNum(1, 272);

    int StarX4 = GetRandomNum(331, 416);
    int StarY4 = GetRandomNum(1, 272);


    while(1) {

	sceCtrlReadBufferPositive(&pad, 1);

	blitAlphaImageToScreen(0, 0 , 480, 272, Background, 0, 0);


      if ((x0 >= (StarX1 - 5) && x0 <= (StarX1 + 5)) && ((y0 >= (StarY1 - 5) && y0 <= (StarY1 + 5))) ) {
	StarX1 = GetRandomNum(1, 110);
	StarY1 = GetRandomNum(1, 272);
      }
      else if ((x0 >= (StarX2 - 5) && x0 <= (StarX2 + 5)) && ((y0 >= (StarY2 - 5) && y0 <= (StarY2 + 5))) ) {
	StarX2 = GetRandomNum(111, 220);
	StarY2 = GetRandomNum(1, 272);
      }
      else if ((x0 >= (StarX3 - 5) && x0 <= (StarX3 + 5)) && ((y0 >= (StarY3 - 5) && y0 <= (StarY3 + 5))) ) {
	StarX3 = GetRandomNum(221, 330);
	StarY3 = GetRandomNum(1, 272);
      }
      else if ((x0 >= (StarX4 - 5) && x0 <= (StarX4 + 5)) && ((y0 >= (StarY4 - 5) && y0 <= (StarY4 + 5))) ) {
	StarX4 = GetRandomNum(331, 416);
	StarY4 = GetRandomNum(1, 272);
      }

	// reset the square
      if(pad.Buttons & PSP_CTRL_SELECT) {
	x0 = 100;
	y0 = 100;
      }

      *Just some up down movements here*
      *Just some up down movements here*
      *Just some up down movements here*

	// If the square is at the end of the screen (left side) set it to 0
      if(x0 < 0) {
	    x0 = 0;
      }
	// Otherwise if the square is at the end of the screen (right side) set it to 430 (screen width minus the square width)
      else if(x0 > ((480 - 64) - x0Width)) {
	    x0 = ((480 - 64) - x0Width);
      }

	// If the square is at the top of the screen set it to 0
      if(y0 < 0) {
	    y0 = 0;
      }
	// Otherwise if the square is at the bottom of the screen set it to 222 (screen height minus the square height)
      else if(y0 > (272 - x0Height)) {
	    y0 = (272 - x0Height);
      }
	// draw our little square and star!
      if(ok >= 1){
	blitAlphaImageToScreen(0, 0, 10, 10, Face, x0, y0);
	blitAlphaImageToScreen(0, 0, 10, 10, Square1, StarX1, StarY1);
	blitAlphaImageToScreen(0, 0, 10, 10, Square2, StarX2, StarY2);
	blitAlphaImageToScreen(0, 0, 10, 10, Square3, StarX3, StarY3);
	blitAlphaImageToScreen(0, 0, 10, 10, Square4, StarX4, StarY4);

	blitAlphaImageToScreen(0, 0, 64, 480, Wall, 416, 0);

      }

	 sceDisplayWaitVblankStart();
	 flipScreen();
    }	

    sceKernelSleepThread();
    return 0;
}

Anyone? It has been five days since I originally posted..

[yaustar]

What is your code in GetRandomNum? Chances are that the function is not returning correct values.

[Auraomega]

No. Tommydanger was right (apart from the memcpy's last parameter). He created an array of u32s, so the size was in fact 512*272*4. Anyway, it crashes, because the buffer is created on stack and the stack is not large enough for that. Either make the declaration static or use malloc.
Also, you could get weird results if you're reading back the framebuffer while it is currently being rendered too. So you'd probably be best off mutexing the memcpy or disabling interrupts during the time and make sure it happens after the rendering of the screen has finished (by hooking sceDisplaySetFramebuf or sceGuSync).

Argh, brain isn't functioning today. It was the stack, once I allocated more to the thread it stopped crashing, but instead it appears to be reverting to a mix of old images blitted to the screen, I think I've done something wrong with assigning the buffer to the image->data.

u32 buffer = (void*)malloc(512*272*4);
    
    Image* screen;
    screen = createImage(480, 272);

    while(1)
    {
         sceCtrlPeekBufferPositive(&pad, 1);
         if(pad.Buttons & PSP_CTRL_SELECT)
         {
            memcpy(buffer, 0x04000000, 512*272*4);
            screen->data = buffer;

When I then blit screen to the screen it gives me a mix of whats already there, the "PSPLink Bootstrap TyRaNiD (c) 2k7 Version v3.0" but instead of it being white it gives it with the colours of the picture that was on screen the previous time.

-Aura

[Insert_Witty_Name]

Also, you could get weird results if you're reading back the framebuffer while it is currently being rendered too. So you'd probably be best off mutexing the memcpy or disabling interrupts during the time and make sure it happens after the rendering of the screen has finished (by hooking sceDisplaySetFramebuf or sceGuSync).

Quoted for emphasis.

[Raphael]

"PSPLink Bootstrap TyRaNiD (c) 2k7 Version v3.0" but instead of it being white it gives it with the colours of the picture that was on screen the previous time.

-Aura

That sounds as if you just draw the image with alpha transparency - however the framebuffers alpha channel is not useable, so you need to disable blending. If that's not the case - refer to my previous posts hint (which IWN quoted).

[Auraomega]

Quoted for emphasis.

Yeah I made sure nothing was writing the to buffer while I was doing so (I suspended all the threads doing this).

Thank you Raphael, for some odd reason I was trying to use alpha, after reviewing the code I have disabled this and it now works fine

-Aura

[HYde]

Ok so I was installing cygwin and then pspdev I made the changes I needed to cygwin.bat ie.

set path=%path%;C:/cygwin/usr/local/pspdev/bin
set PSPSDK=C:/cygwin/usr/local/pspdev

But what I did by accident "so stupid" I typed

set path=%/path%;C:/.......
That dang forward slash some how got saved. So when I compile I get an error that says.
/c/cygwin/usr/local/pspdev/psp/sdk/lib/build.mak: No such file or directory.
I know theres a fix, I found it a long long time ago. All day I've been searching with no results this time. Yes I have done this before :Argh:
I will definitely write it down this time around. If anyone knows the syntax to fix this I would appreciate it. Thats all I can remember about fixing it was typeing something in the command prompt. And just to let you know I have reinstalled cygwin, made both PATH and PSPSDK Environment Variables.

Plus how can you get a clean uninstall of cygwin? That might just be my best bet since I can't find my answer. Hope I made sence I'm a little angry with myself at the moment.

::Edit::
Found out about the cygwin uninstall all through there sites FAQ... duh! Talk about an off day.
...gezz All I had to do is type this into the command prompt.
set PATH=c:/cygwin/usr/local/pspdev/bin;%PATH%
set PSPDEV=c:/cygwin/usr/local/pspdev
Dont know why it wouldn't fix its self through Environmental Varibles Settings..??

[BigSanFrey]

What is your code in GetRandomNum? Chances are that the function is not returning correct values.

int GetRandomNum(int lo, int hi)
{
 SceKernelUtilsMt19937Context ctx;
 sceKernelUtilsMt19937Init(&ctx, time(NULL)); //SEED TO TIME
 u32 rand_val = sceKernelUtilsMt19937UInt(&ctx);
 rand_val = lo + rand_val % hi;
 return (int)rand_val;
}

is my GetRandomNum function

[Raphael]

int GetRandomNum(int lo, int hi)
{
 SceKernelUtilsMt19937Context ctx;
 sceKernelUtilsMt19937Init(&ctx, time(NULL)); //SEED TO TIME
 u32 rand_val = sceKernelUtilsMt19937UInt(&ctx);
 rand_val = lo + rand_val % hi;
 return (int)rand_val;
}

is my GetRandomNum function

That will give you a random number in range [lo, lo+hi-1].

What you probably want is return (lo + (rand_val % (hi - lo + 1)));

[yaustar]

int GetRandomNum(int lo, int hi)
{
 SceKernelUtilsMt19937Context ctx;
 sceKernelUtilsMt19937Init(&ctx, time(NULL)); //SEED TO TIME
 u32 rand_val = sceKernelUtilsMt19937UInt(&ctx);
 rand_val = lo + rand_val % hi;
 return (int)rand_val;
}

is my GetRandomNum function

Thought as much, I fixed this 5 days ago:
http://forums.qj.net/f-psp-developme...4/page732.html
C/C++ Programming Help Thread

[BigSanFrey]

sorry!!
I searched for a random number generator in the earlier parts of this thread and it gave me pretty much that exact code.. weird (and stupid of me!)

[SuperBatXS]

Can you post the full error and the block of code that produces it?

If you want to be even more clever with the GetRandomNum (and because it is in C), you can try this:

SceKernelUtilsMt19937Context InitialiseMtContext()
{
    SceKernelUtilsMt19937Context ctx;
    sceKernelUtilsMt19937Init(&ctx, time(NULL));

    return ctx;
}

int GetRandomNum(int lo, int hi)
{
    static SceKernelUtilsMt19937Context ctx = InitialiseMtContext();

    int rand_val = (int)sceKernelUtilsMt19937UInt(&ctx);
    rand_val = lo + ( rand_val % (hi-lo) );
    return rand_val;
}

int main()
{
    // get random number
    GetRandomNum( 0, 100 ); // ctx gets initialised here the first time the function is called
    GetRandomNum( 0, 100 ); // but not here
    GetRandomNum( 0, 100 ); // nor here

    return 0;
}

Please note, that if I was using C++, I wouldn't have written this code like this. I would use a class.

Ok, i tried that, but i get the error for the static line: "initializer element is not constant".

[eldiablov]

http://www.google.co.uk/search?hl=en...e+Search&meta=

[SuperBatXS]

Will this work then:

int GetRandomNum(int lo, int hi)
{
    static SceKernelUtilsMt19937Context ctx;
    sceKernelUtilsMt19937Init(&ctx, time(NULL));

    int rand_val = (int)sceKernelUtilsMt19937UInt(&ctx);
    rand_val = lo + ( rand_val % (hi-lo) );
    return rand_val;
}

Edit: Never mind, i was being an idiot. That doesn't work. I found it out. :)

[Archaemic]

SceKernelUtilsMt19937Context InitialiseMtContext()
{
    SceKernelUtilsMt19937Context ctx;
    sceKernelUtilsMt19937Init(&ctx, time(NULL));

    return ctx;
}

int GetRandomNum(int lo, int hi)
{
    static int initialized = 0;
    static SceKernelUtilsMt19937Context ctx;
    if(!initialized) {
        ctx = InitialiseMtContext();
        initialized = 1;
    }

    int rand_val = (int)sceKernelUtilsMt19937UInt(&ctx);
    rand_val = lo + ( rand_val % (hi-lo) );
    return rand_val;
}

int main()
{
    // get random number
    GetRandomNum( 0, 100 ); // ctx gets initialised here the first time the function is called
    GetRandomNum( 0, 100 ); // but not here
    GetRandomNum( 0, 100 ); // nor here

    return 0;
}

Here's a hack-y way to do it.

[yaustar]

Ok, i tried that, but i get the error for the static line: "initializer element is not constant".

It is something to do with the array in the struct ctx so copying by value is invalid.

int GetRandomNum(int lo, int hi)
{
    static int initialized = 0;
    static SceKernelUtilsMt19937Context ctx;
    if(!initialized) 
    {
         sceKernelUtilsMt19937Init(&ctx, time(NULL));
        initialized = 1;
    }

    int rand_val = (int)sceKernelUtilsMt19937UInt(&ctx);
    rand_val = lo + ( rand_val % (hi-lo) );
    return rand_val;
}

int main()
{
    // get random number
    GetRandomNum( 0, 100 ); // ctx gets initialised here the first time the function is called
    GetRandomNum( 0, 100 ); // but not here
    GetRandomNum( 0, 100 ); // nor here

    return 0;
}

[SilverSpring]

Ok, i tried that, but i get the error for the static line: "initializer element is not constant".

uh...you're passing the whole struct back? You do realise that SceMt19937Context is 625 Bytes in size.

Also, while Mersenne Twister is good and one of the best prng's there are. It's a lot quicker and more convenient to use the psp's hardware prng. Either via the VFPU's rand registers, or the KIRK crypto engine.

Fortunately, SCE provides a nifty api to access the crypt hw.

int sceDdrdbPrngen(u8 *rand);

You dont have to seed it (KIRK is initialised automatically on boot) and is a pure hw based prng so will be a lot faster (although the exact algo used is unknown - naturally, considering its from the security engine).

It normally returns 20 bytes, but if you only need 0-100 just take a single byte and scale it.

[yaustar]

uh...you're passing the whole struct back? You do realise that SceMt19937Context is 625 Bytes in size.

I was, (it is my original re-done code), since it only happens once throughout the life of the program, it isn't that big of a deal.

[SuperBatXS]

It is something to do with the array in the struct ctx so copying by value is invalid.

int GetRandomNum(int lo, int hi)
{
    static int initialized = 0;
    static SceKernelUtilsMt19937Context ctx;
    if(!initialized) 
    {
         sceKernelUtilsMt19937Init(&ctx, time(NULL));
        initialized = 1;
    }

    int rand_val = (int)sceKernelUtilsMt19937UInt(&ctx);
    rand_val = lo + ( rand_val % (hi-lo) );
    return rand_val;
}


int main()
{
    // get random number
    GetRandomNum( 0, 100 ); // ctx gets initialised here the first time the function is called
    GetRandomNum( 0, 100 ); // but not here
    GetRandomNum( 0, 100 ); // nor here

    return 0;
}

That's giving me random number outside my max and min values.

[yaustar]

That's giving me random number outside my max and min values.

That is impossible. What numbers are you passing in and what are you getting out? Are you sure you are using the right random values ? E.g. Passing in 0 to 480 but setting it to the Y position of an object instead of X?

Write a test program that is just the random number function being called a 1000 times that spits out an error message if it goes beyond the range of the min and max values.

[SuperBatXS]

I just finished doing that. I even checked the values and everything. Even then, some of the values are going outside the min and max!

This is the wierdest problem i have ever had. However, this works perfectly:

int GetRandomNum(int lo, int hi)
{
    SceKernelUtilsMt19937Context ctx;
    sceKernelUtilsMt19937Init(&ctx, time(NULL));

    int rand_val = (int)sceKernelUtilsMt19937UInt(&ctx);
    rand_val = lo + ( rand_val % (hi-lo) );
    return rand_val;
}

I'm just going to stick with this...
My main question is, how do i make a tile system?

[Anti-QuickJay]

Look at all the examples out their....That should give you an idea.
Or you can think about what a tile system does and make one...

[SuperBatXS]

Do you have a link to the examples?

Side note:

OMFG!!!! I got my mp3 decoding code to work!!!!!!!!! Yes!!! Now i don't have to worry about all that lagging!!!

[Judas]

Do you have a link to the examples?

Side note:

OMFG!!!! I got my mp3 decoding code to work!!!!!!!!! Yes!!! Now i don't have to worry about all that lagging!!!

A tile engine is very easy to make. Search for a Lua version, and get the basic idea. From there, it'll be easy to port to C.