C++ last bit of an image Post: 302510270

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Top Forums Programming C++ last bit of an image Post 302510270 by lamachejo on Saturday 2nd of April 2011 02:47:21 PM

04-02-2011

Registered User

C++ last bit of an image

Hi guys, I've been trying to find out what's wrong with the code, g++ doesn't prompt any error but it doesn't do what I want it to do, and after looking at it over and over I can't find anything wrong with it. The code its quite simple:

I need to save the last bit of every position on the vector and to form a word, for example:
buffer[0] has 00110011
buffer[1] has 11000010

I need to get the last bit and form a letter every 8 bits to decode the sentence.

buffer is a dinamic vector that has the image info loaded on it, cadena is where I want to store the "decoded " letters

Code:

 void revelarPGM (char* &cadena,unsigned char buffer[]) { 
 int binario=0;			
 int j=0;	
 cadena=new char[50000];
 for (int i=0; i<262144; i++) {
     if((buffer[i]&1)==0){ // HERE i use the AND operator to get the last bit, if it is
           binario=(binario<<1);  // A 0, i just shift once
     }else{   
	   binario=(binario<<1);  //IF it is a 1, i shift and add a 1 with the OR
  	   binario=(binario|1);    
     }
   if (i%7==0) {               // WHEN i get 8 bits i store the letter in cadena
          cadena[j]=binario;
          j++;
	  cout << binario << endl;
          binario=0;
  }
 }
 for (int i=0; i<300; i++)
cout << cadena[i];  // cout to see the words i stored.
delete [] cadena;
}

I hope I made myself clear. The problem is I am getting rubbish. But everytime i look at the code, it seems alright to me.

edit: tried to edit the title since i forgot to add it was C++ but it wont allow me now.

Last edited by lamachejo; 04-02-2011 at 03:52 PM..

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fixup_datafile

fixup_datafile(3alleg4) 					  Allegro manual					   fixup_datafile(3alleg4)

NAME

       fixup_datafile - Fixes truecolor images in compiled datafiles. Allegro game programming library.

SYNOPSIS

       #include <allegro.h>

       void fixup_datafile(DATAFILE *data);

DESCRIPTION

       If  you are using compiled datafiles (produced by the dat2s and dat2c utilities) on a platform that doesn't support constructors (currently
       any non GCC-based platform), or if the datafiles contain truecolor images, you must call this function once after your set the  video  mode
       that  you  will	be  using. This will ensure the datafiles are properly initialised in the first case and convert the color values into the
       appropriate format in the second case. It handles flipping between RGB and BGR formats, and converting between different color depths when-
       ever  that  can	be  done  without  changing  the size of the image (ie. changing 15<->16-bit hicolor for both bitmaps and RLE sprites, and
       24<->32-bit truecolor for RLE sprites).

       Note that you can only call this once and expect it to work correctly, because after the call the DATAFILE you fixed up is permanently con-
       verted  to whatever is the current component ordering for your screen mode. If you call fixup_datafile again, the function assumes you have
       a freshly loaded datafile. It cannot "undo" the previous conversion.

       If your program supports changing resolution and/or color depth during runtime, you have two choices:  either  call  fixup_datafile()  just
       once  and  hope	that  the component ordering and bit depth doesn't change when the screen mode changes (unlikely). Or, you can reload your
       datafiles when the screen mode changes.

SEE ALSO

       set_gfx_mode(3alleg4), set_color_conversion(3alleg4)

Allegro 							   version 4.4.2					   fixup_datafile(3alleg4)