Problem

        
// for ( ; ; )
// {

// gl_copyscreen(physicalscreen);
// gl_setpalettecolor(c, 0, 0, 0);
//// y = 0;

// c = 3;

// for (i = 0; i < 64; i++)
{
// for (i=1;i<768;i++) palette=palette<i>>>8;
//init_svgalib(&virtualscreen);
//gl_setpalette(palette);
// for (i=1;i<768;i++) palette<i>=palette[i]>>4;
    

    
// Function reads the byte values from the file

void readpcximage(FILE *file, void *target, int size)
{
	// Variables

	unsigned char buf;		// Buffer (unsigned??)
	unsigned int counter;		// Counter (now Why is this unsigned?)
        int i=0;			// Looping variable I assume

        
	// Assuming size is CORRECT, read that many bytes	
        while(i <= size)
        {
	        /* Get one byte: store it in buf */
                fread(&buf,1,1,file);

                /* Check the 2 most significant bits */
                if ((buf&192)==192)
                {
		     /* Number of times to repeat next byte */
                     counter=(buf&63); 

		     /* Get the next byte */
                     fread(&buf,1,1,file); 

		     /* Copy byte read counter times into target */
                     for(;counter > 0; counter--) 
                     { 
			  // I''m dubious to validity of casting target

                          // as an array of char and setting target<i>,
			  // This could easily be the problem, since
			  // we dont break if i >= size.

		          ((char*)target)[i]=buf;
                          i++; 
                     }


                }
                else
                {
                     // Again I''m dubious. But whatever.

                     ((char*)target)[i]=buf;
                     i++;
                }
	}
}

// Allocates an image structure and returns it

void *readpcx(FILE *file, char *palette,unsigned short int *length, unsigned short int *height)
{
	PCX_Header header;
        void *target;
        
	// Move to start of file

	fseek(file,0,SEEK_SET);

	// Read the header information: incidentally, why is everything
	// unsigned? I''m not sure if do that works ok with unsigned values...

        fread(&header,sizeof(PCX_Header),1,file);

	// Check the header signature

        if ((header.signature! = 0x0a) || (header.version! = 5))
             return(NULL);
        else
	{
	        /* Set the height and length values in the argument*/
                *length=header.xmax+1-header.xmin;
                *height=header.ymax+1-header.ymin;

                /* Allocate the sprite buffer; simply H*W bytes */
                target = (void *) malloc((*length)*(*height));

                /* Read the image */
                readpcximage(file, target, (*length)*(*height));

		// Seek to 768 bytes from the end

                fseek(file,-768,SEEK_END);

                /* Get the palette */
                fread(palette, 1, 768, file);

                /* Return memory structure
                return(target);
         }
}
    

    

#include <stdio.h> 
#include <vga.h> 
#include <vgagl.h> 
#include <vgakeyboard.h>   


void *readpcx(FILE *file, char *palette,unsigned short int *length, unsigned short int *height);


void init_svgalib (GraphicsContext *physicalscreen);
void init_svgalib (GraphicsContext *virtualscreen);
void exit_svgalib();

GraphicsContext *physicalscreen;
GraphicsContext *virtualscreen;

int main(void)
 {
  FILE *file;
  FILE *file3;
  void *image;
  void *image3;
  int i;
  int x2,y2;
  char ch;
  unsigned short int length, height;
  unsigned char palette[768];
  int x;
  char *keymap;
  int i2,
    j,
    b,
    y,
    c;

  vga_init();
  vga_setmode(5);
  gl_setcontextvga(5);
  physicalscreen = gl_allocatecontext();
  gl_getcontext(physicalscreen);
  gl_setcontextvgavirtual(5);
  virtualscreen = gl_allocatecontext();
  gl_getcontext(virtualscreen);

  x2=0;
  y2=0;

 if ((file3=fopen("frank5.pcx","r"))==NULL)
 {
 printf("Can''t open file!\n");
 return(1);
 }

 if ((image3=readpcx(file3,palette,&length,&height))==NULL)
 {
  }


if ((file=fopen("land.pcx","r"))==NULL)
{
printf("Can''t open file!\n");
return(1);
}

if ((image=readpcx(file,palette,&length,&height))==NULL)
{
 }

 
   fclose(file);
   printf("Image is %dx%d sized.\n",length,height);
   if((length>320)||(height>200)) {
   printf("Image is too big!\n");
   return(1);
 }


   gl_setcontext(virtualscreen);

   {
    gl_clearscreen(0);
    gl_copyscreen(virtualscreen);
    gl_putbox(10,10,320,200,file);
    gl_putbox(x2,y2,length,height,file3);
    vga_waitretrace();
   }

 keyboard_init();


 while( 1 )
 {
 
        keyboard_update();

        if( keyboard_keypressed( SCANCODE_CURSORBLOCKUP ))
         {
          y2 = y2 -3;
          gl_setcontext(virtualscreen);

          if ((file3=fopen("frank5.pcx","r"))==NULL)
          {
            printf("Can''t open file!\n");
            return(1);
          }

          if ((image3=readpcx(file3,palette,&length,&height))==NULL)
          {
          }

          gl_clearscreen(0);
          gl_putbox(10,10,320,200,file);
          gl_putbox(x2,y2,length,height,file3);
          vga_waitretrace();
          gl_copyscreen(physicalscreen);
         }

        if( keyboard_keypressed( SCANCODE_CURSORBLOCKDOWN ))
         {
           y2 = y2 +3;
           gl_clearscreen(0);
           gl_putbox(10,10,320,200,file);
           gl_putbox(x2,y2,length,height,file3);

           vga_waitretrace();
           gl_copyscreen(physicalscreen);

      
           if ((file=fopen("land.pcx","r"))==NULL)
           {
             printf("Can''t open file!\n");
             return(1);
           }

           if ((image=readpcx(file,palette,&length,&height))==NULL)
           {
           }

           if ((file3=fopen("frank3.pcx","r"))==NULL)
           {
             printf("Can''t open file!\n");
             return(1);
           }

           if ((image3=readpcx(file3,palette,&length,&height))==NULL)
           {
           }

         }

         if( keyboard_keypressed( SCANCODE_CURSORBLOCKRIGHT ))
         {
           x2 = x2+3;
           if ((file3=fopen("frank2.pcx","r"))==NULL)
           {
             printf("Can''t open file!\n");
             return(1);
           }

  if ((image3=readpcx(file3,palette,&length,&height))==NULL)
    {
    }
         gl_clearscreen(0);
         gl_putbox(10,10,320,200,file);
         gl_putbox(x2,y2,60,40, file3);
         vga_waitretrace();
         gl_copyscreen(physicalscreen);
       }

          if( keyboard_keypressed( SCANCODE_CURSORBLOCKLEFT ))
           {
             x2 = x2-3;

              if ((file3=fopen("frank4.pcx","r"))==NULL)
              {
               printf("Can''t open file!\n");
               return(1);
              }

              if ((image3=readpcx(file3,palette,&length,&height))==NULL)
                {
                }


           gl_clearscreen(0);
           gl_putbox(10,10,320,200,file);
           gl_putbox(x2,y2,60,40, file3);
           vga_waitretrace();
           gl_copyscreen(physicalscreen);
         }

    if( keyboard_keypressed( SCANCODE_ESCAPE ) )
    {
     break;
    }
    }

   gl_clearscreen(0);
   vga_setmode(0);
   exit_svgalib();
   keyboard_close();
   return(0);
 }

[/source]
pcx.c :

[source]

#include <stdio.h> 
#include <stdlib.h> 
#include <string.h>   

typedef struct
 {
  char signature;
  char version;
  char encoding;
  char bytes_per_pixel;
  unsigned short int xmin;
  unsigned short int ymin;
  unsigned short int xmax;
  unsigned short int ymax;
  unsigned short int vres;
  unsigned short int hres;
  char palette[48];
  char reserved;
  char color_layers;
  unsigned short int bytes_per_line;
  unsigned short int palette_type;
  char unused[58];
 }PCX_Header;




void readpcximage(FILE * file,void * target,int size) 
                          {                           
                            unsigned char buf;
                           unsigned int counter;
                           int i=0;
                           while(i<=size) 
                            {
                            
                            fread(&buf,1,1,file);
                            
                            if ((buf&192)==192)
                            {
                             
                             counter=(buf&63);         
                             fread(&buf,1,1,file);    
                             for(;counter>0;counter--) 
                             {                                         ((char*)target)<i>=buf;
                             i++;   
                             }
                            }
                            else
                            {
                             
                             ((char*)target)[i]=buf;
                             i++;   
                            }
                            }
                           }
                      

                          void *readpcx(FILE *file, char *palette,unsigned short int *length, unsigned short int *height)
                           
                           {
                           PCX_Header header;
                           void *target;
                           fseek(file,0,SEEK_SET);
                           fread(&header,sizeof(PCX_Header),1,file);   
                           if((header.signature!=0x0a)||(header.version!=5))
                            return(NULL);
                           else
                           {
                           target=(void *)malloc((*length)*(*height));
                           readpcximage(file,target,(*length)*(*height));
                           fseek(file,-768,SEEK_END);
                            fread(palette,1,768,file);
                           return(target);
                           return(0);
                          }
                        }

    

    
#include <stdio.h>
#include <unistd.h>
#include <vga.h>
#include <vgagl.h>
#include <vgakeyboard.h>
#include <stdlib.h>
#include <string.h>


// Structures

typedef struct
{
    char signature;
    char version;
    char encoding;
    char bytes_per_pixel;
    unsigned short int xmin;
    unsigned short int ymin;
    unsigned short int xmax;
    unsigned short int ymax;
    unsigned short int vres;
    unsigned short int hres;
    char palette[48];
    char reserved;
    char color_layers;
    unsigned short int bytes_per_line;
    unsigned short int palette_type;
    char unused[58];

} PCX_Header;


// Prototyping

void *readpcx (FILE *file,
               char *palette,
               unsigned short int *length,
               unsigned short int *height);


void init_svgalib (GraphicsContext *gc);
void exit_svgalib();


// Globals

GraphicsContext *physicalscreen;
GraphicsContext *virtualscreen;


int main(void)
{
    FILE *file;
    FILE *file3;
    void *image;
    void *image3;
    int i;
    int x2,y2;
    char ch;
    unsigned short int length, height;
    unsigned char palette[768];
    int x;
    char *keymap;
    int i2,
    j,
    b,
    y,
    c;


    // Load file 1

    if ((file3=fopen("one.pcx","r"))==NULL)
    {
        printf ("Can't open file!\n");
        exit (1);
    }
    if ((image3=readpcx(file3,palette,&length,&height))==NULL)
    {
        printf ("File load failure.\n");
        exit (0);
    }


    // Load file 2

    if ((file=fopen("one.pcx","r"))==NULL)
    {
        printf("Can't open file!\n");
        return(1);
    }
    if ((image=readpcx(file,palette,&length,&height))==NULL)
    {
        printf ("File load failure.\n");
        exit (0);
    }


    // Close files

    fclose (file);
    fclose (file3);


    // Init vga

    vga_init();
    vga_setmode(5);
    gl_setcontextvga(5);
    physicalscreen = gl_allocatecontext();
    //gl_getcontext(physicalscreen);
    init_svgalib (physicalscreen);
    gl_setcontextvgavirtual(5);
    virtualscreen = gl_allocatecontext();
    //gl_getcontext(virtualscreen);
    init_svgalib (virtualscreen);


    // Init positions

    x2=0;
    y2=0;


    // Print image data

    printf("Image is %dx%d sized.\n",length,height);
    if ((length>320) || (height>200))
    {
        printf ("Image is too big!\n");
        exit (1);
    }


    // Virtual context stuff

    gl_setcontext(virtualscreen);
    gl_clearscreen(0);
    gl_copyscreen(virtualscreen);


    // Init key listener

    keyboard_init();


    // Enter main loop

    while( 1 )
    {
        keyboard_update();


        if(keyboard_keypressed(SCANCODE_ESCAPE))
        {
           gl_clearscreen(0);
           vga_setmode(0);
           exit_svgalib();
           keyboard_close();
           return(0);
        }


        // Draw it all again

        gl_fillbox (0, 0, 299, 199, gl_rgbcolor (0, 50, 3));
        gl_putbox(10,10,length,height,image);
        gl_putbox(50,50,length,height,image3);
        gl_line (0, 0, x2, y2, gl_rgbcolor (0, 3, 50));
        gl_copyscreen(physicalscreen);
        ++x2;
        ++y2;
        printf ("X is: %d, Y is: %d\n", x2, y2);


        // Sleep for a bit

        sleep (1);
    }


    return (0);
}


void readpcximage(FILE * file,void * target,int size)
{
    unsigned char buf;
    unsigned int counter;
    int i=0;


    while (i <= size)
    {
        fread(&buf,1,1,file);


        if ((buf&192)==192)
        {
            counter=(buf&63);


            fread(&buf,1,1,file);


            for(;counter>0;counter--)
            {
                ((char*)target)<i>=buf;
                i++;

                if (i >= size)
                    break;
            }
        }
        else
        {
            ((char*)target)[i]=buf;
            i++;
        }
    }
}


void *readpcx(FILE *file, char *palette,unsigned short int *length, unsigned short int *height)
{
    PCX_Header header;
    void *target;
    fseek(file,0,SEEK_SET);


    fread(&header,sizeof(PCX_Header),1,file);


    *length=header.xmax+1-header.xmin;
    *height=header.ymax+1-header.ymin;


    if((header.signature!=0x0a)||(header.version!=5))
        return(NULL);
    else
    {
        target=(void *)malloc((*length)*(*height));


        readpcximage(file,target,(*length)*(*height));


        fseek(file,-768,SEEK_END);


        fread(palette,1,768,file);


        return(target);
    }
}


void init_svgalib (GraphicsContext *gc)
{
    if (vga_init()!=0)
    {
        printf("Error initialising svgalib!\n");
        exit(1);
    }


    if (vga_setmode(G640x480x64K)!=0)
    {
        printf("Can't set mode 640x480x64K!\n");
        exit(1);
    }


    if (gl_setcontextvga(G640x480x64K)!=0)
    {
        printf("Error setting context!\n");
        exit(1);
    }


    gl_getcontext(gc);


    if (gl_setcontextvgavirtual(G640x480x64K)!=0)
    {
        printf("Error setting virtual context!\n");
        exit(1);
    }
}


void exit_svgalib()
{
    vga_setmode(TEXT);
}