/* CRC.CPP - Finds the CRC of a file

		by Colin Bennett

(for Borland Turbo C++)

Freely use, distribute, and modify.

How to contact me:
	The Code Room BBS (408.266.3818)
	The Net (cbennett@svpal.org)
	Snail Mail (719 Bicknell Road, Los Gatos, CA 95030-1645)

Set tabs to 3 spaces for proper indentation.

*/


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


unsigned CRC(char *fname)
	{
	unsigned a = 0;
	int c;
	unsigned i;
	FILE *fp;

	fp = fopen(fname, "r");
	if (!fp)
		{
		printf("File not found\n");
		exit(1);
		}

	while (1)
		{
		c = fgetc(fp);
		if (c == EOF)
			break;

		a = a ^ (c << 8);

		for (i = 0; i++ < 8;)
			{
			if (a & 0x8000)
				a = (a << 1) ^ 0x1021;
			else
				a <<= 1;
			}
		}

	fclose(fp);

	asm {
		mov ax,a
		xchg ah,al
		}

	return (_AX);
	}


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

	if (argc != 2)
		{
		printf("Usage: CRC <filename>\n");
		exit(0);
		}


	crc = CRC(argv[1]);

	printf("The CRC is %04X\n", crc);

	return 0;
	}
  

  _asm  //NOTE THE UNDERSCORE{     //ASM goes here}  

  unsigned retVal = 0;__asm{	mov ax, word ptr[a]	xchg ah, al	mov word ptr[retVal], ax;};return retVal;