/***
** 
** Sample Code Bitmap Displayer
** 
** Please check this file before downloading to determine what will you need
** for this file to work.
** Please read the disclaimer before using this code.
**
** This file has to be compiled with SVGALIB System from a project file.
** SVGALIB.LIB is contained SVGACC25.ZIP
** Please check these files in the C MS-DOS archives in SimTelnet or Garbo.
**
** Do copy the "svgacc.h" and "svgademo.h" into your c compiler "include" directory
**
** if you want to use another VGA system. Please change
** all the function referal to SVGALIB system to your own.
** But just make sure the VGA system displays 256 color for you
** to access 256 color bitmap.
**
** You have to use project file, in order to access the library  
** function in svgalib.lib. Please read your compiler
** documentation for using project file.
** 
** Ahmad Hafiz: 
** http://www.geocities.com/SiliconValley/Vista/2459
** cobra_ayaq@hotmail.com
** 
** Please set TAB to 2 (in your c editor, for the text to aligned properly)
**
****/

#include <stdio.h>
#include <conio.h>
#include <svgacc.h> /* i'm using a SVGALIB VGA system */
#include <svgademo.h>

typedef unsigned char BYTE;
typedef unsigned int UINT;
typedef unsigned long DWORD;
typedef unsigned int WORD;
typedef signed long LONG;

typedef struct tagBITMAPFILEHEADER {    /* bmfh */
    UINT    bfType;
    DWORD   bfSize;
    UINT    bfReserved1;
    UINT    bfReserved2;
    DWORD   bfOffBits;
} BITMAPFILEHEADER;

typedef struct tagBITMAPINFOHEADER {    /* bmih */
    DWORD   biSize;
    LONG    biWidth;
    LONG    biHeight;
    WORD    biPlanes;
    WORD    biBitCount;
    DWORD   biCompression;
    DWORD   biSizeImage;
    LONG    biXPelsPerMeter;
    LONG    biYPelsPerMeter;
    DWORD   biClrUsed;
    DWORD   biClrImportant;
} BITMAPINFOHEADER;

unsigned getbits(unsigned x, int p, int n)
{ return(x>>(p+1-n)) & ~(~0<<n); }

/***
**
** from command prompt type "C:\>bitmap filetodisplay.bmp"
** or from your compiler set the argument to be filetodisplay.bmp
**
***/
int main(int argc, char **argv)
{
FILE *fp;
BITMAPFILEHEADER bmfh={0};
BITMAPINFOHEADER bmih={0};
DWORD index;
BYTE ch;
int startvmode;
int bmpcolour;
int y,x,q,i=0,j=0;
PaletteData pal3={0};

	if(argc==1) return 0; 
	if((fp=fopen(argv[1],"rb"))==NULL) return 0;

	fread(&bmfh,sizeof(bmfh),1,fp); /* read bitmap file header */
	fread(&bmih,sizeof(bmih),1,fp); /* read bitmap info header */

	/* determine type of window bitmaps */
	if(bmih.biBitCount==8) bmpcolour=256;
	if(bmih.biBitCount==4) bmpcolour=16;
	if(bmih.biBitCount==1) bmpcolour=2;

	/* * * * * * * * * * * * * * * * * *
	 read the palette information
	 from MSB b,g,r,i (i=ignore)
	* * * * * * * * * * * * * * * * * * */
	for(index=0;index<bmpcolour;index++)
	{
		pal3[index].b =	fgetc(fp) >> 2;
		pal3[index].g = fgetc(fp) >> 2;
		pal3[index].r = fgetc(fp) >> 2;
		fgetc(fp);
	}

 	startvmode=videomodeget(); /* save video mode - svgalib system */
	whichvga(); /* determine which vga - svgalib system */
	res320(); /* resolution - svgalib system */


	palset(pal3,0,bmpcolour-1); /* setting palette for VGA 256 colour - svgalib system */

	/* please note that drwpoint is a SVGALIB VGA system */

	switch (bmpcolour){
	case 256: /* draw 256 colour bitmap */

			/* read the bitmap pixel */
			for(y=0,index=0; index<=bmih.biSizeImage-bmih.biWidth; index+=(bmih.biWidth+1),y--)
				{
				for(x=0,q=0;q<bmih.biWidth;q++,x++)
					drwpoint(XOR,(byte)getc(fp),x+i,y+j+bmih.biHeight);

				/* ignoring the appended byte for bitmaps which is not multiply of 4*/
					switch(bmih.biWidth%4){
						case 1:fgetc(fp);
						case 2:fgetc(fp);
						case 3:fgetc(fp);
						case 0:break;
					}
			}
			break;
	case 16: /* draw 16 colour bitmap */

			if(bmih.biSizeImage==0)
				bmih.biSizeImage=bmfh.bfSize-bmfh.bfOffBits;
			for(y=0,index=0; index<bmih.biSizeImage; index+=(bmih.biSizeImage/bmih.biHeight),y--)
				for(x=0,q=0;q<bmih.biSizeImage/bmih.biHeight;q++,x+=2){
              				ch=fgetc(fp);
					if(q*2<bmih.biWidth){
						drwpoint(XOR, getbits(ch,7,4),x+i,y+j+bmih.biHeight);
						drwpoint(XOR, getbits(ch,3,4),x+i+1,y+j+bmih.biHeight);
					}
				}
				/* ignoring the appended byte for bitmaps which is not multiply of 4*/
				switch(bmih.biWidth%4){
					case 1:fgetc(fp);
					case 2:fgetc(fp);
					case 3:fgetc(fp);
					case 0:break;
				}
			break;

	case 1:
	/* this is your assignment */
        break;
	}


	getch(); /* pause */
 	videomodeset(startvmode); /* set to original video mode - svgalib system*/
	fclose(fp); /* close file pointer */
}