/*
 * Morrow's S record down loader
 * 	Len Edmondson
 *	May 1984
 *
 * S record types
 */

#include <stdio.h>

#define until(a) while(!(a))

#define XON 17
#define XOFF 19

#define BUFSIZE 512
#define START '0'
#define SHIP2 '1'
#define SHIP3 '2'
#define TERM3 '8'
#define TERM2 '9'
#define YES 1
#define NO 0
#define IBUFSIZE 256

#define REMOTE (1 << 10)
#define REMTTY 1
#define LOCTTY 0

char sum = 0;
char db = NO;

char lbuf [BUFSIZE], rbuf [BUFSIZE];
char *lp, *rp;

char buf [BUFSIZE];

char *ip, *op;
int icount = 0;
long lineno = 0;
int baud = 9600;

main (ac, av)
	char **av;
	{
	extern char *sbrk();
	static char srec = NO;
	static lcommand = NO;
	static char c;
	int i; 
	int b;


/*
 * Example mon 1200
 */

	if (ac != 1)
		baud = atoi (av[1]);


	sinit ();		/* Hardward initialize */

	lp = lbuf;
	rp = rbuf;

	for (;;)
		{
		i = sread ();	/* read a character */
		
		c = i & 0177;

		if (i & REMOTE)
			{
			if (c == 'S' && rp == rbuf)
				srec = YES;

			if (c != '\r')
				*rp++ = c;

			if (!srec)
				swrite (c, LOCTTY);


			if (c == '\n')
				{
				if (srec)
					{
					*rp = 0;
					process (rbuf);
					srec = NO;
					}

				rp = rbuf;
				}


			}

		else		/* from local */
			{
			swrite (c, REMTTY);
			}
		}
	}

/*
 * <S0><1 byte data count><data><checksum>
 * <S1><1 byte data count><2 byte address><data><checksum>
 * <S2><1 byte data count><3 byte address><data><checksum>
 * <S8><1 byte data count><3 byte address><checksum>
 * <S9><1 byte data count><3 byte address><checksum>
 */

process (a)
	char *a;
	{
	static char *oldaddress;
	static char type, *olda, *address;
	static char namebuf [BUFSIZE];
	static long count, x;
	static (*f)();

	sum = 0;

	olda = a;

	a++;		/* skip S */

	type = *a++;

	if (!index ("01289", type))
		{
		complain ("Unknown S-record type\n");
		return;
		}


	count = htoi (a);
	a += 2;

	if (count * 2 + 5 != strlen (olda))
		{
		complain ("Byte data count error.\n");
		return;
		}


/*
 * address
 */

	if (type == START)
		{
		x = (long) namebuf;
		}

	else
		{
		x = htoi (a);
		a += 2;


		x *= 256;
		x += htoi (a);
		a += 2;

		if (type == SHIP3 || type == TERM3)
			{
			x *= 256;
			x += htoi (a);
			a += 2;
			}
		}

	address = (char *) x;

/*
 * data
 */

	switch (type)
		{
		case SHIP2:
			{
			count -= 3;
			break;
			}

		case SHIP3:
			{
			count -= 4;
			break;
			}

		case TERM2:
		case TERM3:
			{
			count = 0;
			break;
			}

		case START:
			{
			count--;
			break;
			}
		}


	while (count--)
		{
		if (db && type != START)
			{
			htoi (a);
			}
		else
			{
			*address++ = htoi (a);
			}

		a +=2;
		}

/*
 * checksum
 */

	htoi (a);
	a += 2;

	sum++;

	if (sum)
		{
		complain ("Checksum error.\n");
		return;
		}

	if (*a != '\n')
		{
		complain ("Missing NEWLINE\n");
		return;
		}


	switch (type)
		{
		case START:
			{
			prs (namebuf);
			prs ("\n");
			break;
			}

		case TERM2:
		case TERM3:
			{
			prs ("\nSuccessful download\n");

			prs ("Execution starts at ");
			prhex (address);
			prs ("\n");

			if (!db)
				{
				f = address;
				(*f)();
				}

			break;
			}
		}
	}

complain (a)
	char *a;
	{
	prs (buf);

	sprintf (buf, "line %ld: %s\n", lineno, a);
	prs (buf);
	}

/*
 * Bits.
 */

#define OUTREADY (1 << 0)
#define INREADY (1 << 1)

/*
 * Modes.
 */

#define REG1 0x6e
#define REG2_9600 0x7d		/* 9600 baud */
#define REG2_1200 0x78		/* 1200 baud */

#define REG3 0x27


/*
 * Hardware initialization.
 */

sinit ()
	{
	sopen (LOCTTY, 9600);
	sopen (REMTTY, baud);
	}

htoi (a)
	char *a;
	{
	char i;

	i = hval (*a++);

	i *= 16;

	i += hval (*a);

	sum += i;
	
	return 0377 & i;
	}

hval (a)
	char a;
	{
	if (isdigit (a))
		{
		a += (0 - '0');
		}

	else if (isupper (a))
		{
		a += (10 - 'A');
		}

	else if (islower (a))
		{
		a += (10 - 'a');
		}

	return a;
	}

isdigit (a)
	{
	return '0' <= a && a <= '9';
	}

isupper (a)
	{
	return 'A' <= a && a <= 'Z';
	}

islower (a)
	{
	return 'a' <= a && a <= 'z';
	}

prs (a)
	char *a;
	{
	for (; *a; a++)
		{
		if (*a == '\n')
			swrite ('\r', LOCTTY);

		swrite (*a, LOCTTY);
		}
	}

prhex (a)
	long a;
	{
	static char b [16];

	sprintf (b, "%lx", a);
	prs (b);
	}