/* Read a Bitmap File */

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

/* Structures */
typedef struct
{
int rows; int cols; unsigned char* data;
} sImage;

/* Functions */
long getImageInfo(FILE*, long, int);

int main(int argc, char * argv[])
{

 FILE            *bmpInput;
 char		 signature[2];	      /* Signature of the Image File BM = BMP */
 int             nRows, nCols;        /* Row and Column size of the Image */
 int             xpixpeRm, ypixpeRm;  /* Pixel/m */
 long            nColors;             /* BMP number of colors */
 long            fileSize;            /* BMP file size */
 long            vectorSize;          /* BMP's raster data in number of bytes */
 int		 nBits;	              /* # of BIts per Pixel */
 int		 rasterOffset;        /* Beginning of the Raster Data */
 int             i;


 if(argc<2) {
   printf("Usage: %s bmpInput.bmp\n", argv[0]);
   exit(0);
 }
 printf("Reading filename %s\n", argv[1]);

 if ((bmpInput = fopen(argv[1], "rb")) == NULL)
 {
	 printf("Can not read BMP file");
	 exit(0);
 } /* Read BMP input file */

 fseek(bmpInput, 0L, SEEK_SET);   /* File pointer at byte #0 */

 /* Signature of the File BM = BMP at byte # 0*/
 for(i=0; i<2; i++)
 {
	signature[i] = (char)getImageInfo(bmpInput, i, 1);
 }
 if ((signature[0] == 'B') && (signature[1] == 'M')) printf("It is verified that the Image is in Bitmap format\n");
 else
 {
	 printf("The image is not a bitmap format, quitting....\n");
	 exit(0);
 }

 /* Read BMP bits/pixel at byte #28 */
 nBits = (int)getImageInfo(bmpInput, 28, 2);
 printf("The Image is \t%d-bit\n", nBits);

 /* Position of First Raster Data at byte # 10*/
 rasterOffset = (int)getImageInfo(bmpInput, 10, 4);
 printf("The beginning of the Raster Data \nis at \t\t%d byte\n", rasterOffset);

 /* Read BMP file size at byte # 2 */
 fileSize = getImageInfo(bmpInput, 2, 4);
 printf("File size is \t%ld byte\n", fileSize);

  /* Read BMP width at byte #18 */
 nCols = (int)getImageInfo(bmpInput, 18, 4);
 printf("Width: \t\t%d\n", nCols);

 /* Read BMP height at byte #22 */
 nRows = (int)getImageInfo(bmpInput, 22, 4);
 printf("Height: \t%d\n", nRows);

 /* # of Pixels in a meter in x direction at byte # 38 */
 xpixpeRm = (int)getImageInfo(bmpInput, 38, 4);
 printf("Image has \t%d pixels per m in x-dir.\n", xpixpeRm);

 /* # of Pixels in a meter in y direction at byte # 42 */
 ypixpeRm = getImageInfo(bmpInput, 42, 4);
 printf("Image has \t%d pixels per m in y-dir.\n", ypixpeRm);

 /* Read number of colors at byte #46 */
 nColors = pow(2L,nBits);
 printf("There are \t%ld number of Colors \n", nColors);

 vectorSize = (long)((long)nCols*(long)nRows);
 printf("Vector Size is \t%ld\n", vectorSize);

 fclose (bmpInput);

 } /* end of main */


 long getImageInfo(FILE* inputFile, long offset, int numberOfChars)
 {

  unsigned char   *ptrC;
  long            value=0L;
  unsigned char   dummy;
  int             i;

  dummy = '0'; ptrC = &dummy;

  fseek(inputFile, offset, SEEK_SET);

  for(i=1; i<=numberOfChars; i++)
  {
     fread(ptrC, sizeof(char), 1, inputFile);

     value = (long)(value + (*ptrC)*(pow(256, (i-1))));
  }

  return(value);

 } /* end of getImageInfo */