/*
* load - convert a hex file to a com file
*
* Expanded to HEXCOM by John Elliott, 25-5-1998
*
* Compiles with gcc or Pacific C
*
*/

#include <stdio.h>

unsigned char checksum;
int L;

FILE *fpout;

unsigned char getbyte () {
	register int c;
	unsigned char x;

	c = getchar ();
	if ('0' <= c && c <= '9')
		x = c - '0';
	else
		if ('A' <= c && c <= 'F')
			x = c - 'A' + 10;
		else
			goto funny;

	x <<= 4;
	c = getchar ();
	if ('0' <= c && c <= '9')
		x |= c - '0';
	else
		if ('A' <= c && c <= 'F')
			x |= c - 'A' + 10;
		else {
funny:
			fprintf (stderr, "Funny hex letter %c\n", c);
			exit (2);
		}
		checksum += x;
		return x;
}

main (int argc, char **argv) {
	register unsigned i, n;
	char c, buf[64];
	unsigned type = 1;
	unsigned int al, ah, addr = 0, naddr;

	L = 0;
	if (argc < 2) fpout = stdout;
	else fpout = fopen(argv[1],"wb");

	do {
		do {
			c = getchar ();
			if (c == EOF) {
				fprintf (stderr, "Premature EOF colon missing\n");
				exit (1);
			}
		} while (c != ':');

		++L;
		checksum = 0;
		n = getbyte (); /* bytes / line */
		ah = getbyte ();
		al = getbyte ();


		switch (type = getbyte ())
		{
		case 0:
			if (!n) /* MAC uses a line with no bytes as EOF */
			{
				type = 1;
				break;
			}
			naddr = (ah << 8) | al;
			if (!addr) addr = naddr;
			else while (addr < naddr)
			{
				fwrite("", 1, 1, fpout);
				++addr;
			}
			if (addr > naddr)
			{
				fprintf(stderr,
					"Line %d: Records out of sequence at %x > %x\n",
					L, naddr, addr);
				exit(1);
			}

			for (i = 0; i < n; i++)
				buf[i] = getbyte ();
			fwrite (buf, 1, n, fpout);
			break;

		case 1:
			break;

		default:
			fprintf (stderr, "Line %d: Funny record type %d\n", L, type);
			exit (1);
		}

		(void) getbyte ();
		if (checksum != 0)
		{
			fprintf (stderr, "Line %d: Checksum error", L);
			exit (2);
		}

		addr += n;

	} while (type != 1);
	exit(0);
}