/*  FRCProg v0.1
 *  (c) 2006 Harry Bock, Team 1350
 *  Load a HEX file compiled for the PIC18Fxxxx used for the FRC
 *
 *  This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */
 
#include "ihex.h"
#include "frcprog.h"
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

/* Parse an Intel HEX file (output from mcc18) and return
 * a map of the PIC memory we are to write.
 */
byte *ihex_parse_file( char *fn )
{
	int line = 0, c, chk;
	char buf[64], *record;
	struct ihex_record rec;
	
	FILE *fp = fopen(fn, "r");
	
	byte *picmem = (byte*)malloc(PIC_RAM_SIZE);
	if(!picmem) {
		fprintf(stderr, "Error allocating PIC memory... terminating.\n");
		exit(1);
	}
	if(!fp) {
		fprintf(stderr, "Error opening file %s!\n", fn);
		goto error;
	}
	
	memset(picmem, 0, PIC_RAM_SIZE);
	while(!feof(fp)) {
		fgets(buf, 64, fp);
		if(*buf != ':') {
			fprintf(stderr, "Error reading input, not a valid Intel HEX file!");
			goto error;
		}
		line++;
		record = buf+1;
	
		// :llaaaatt - length, address, type
		sscanf(record,   IHEX_SCANBYTE, &rec.length);
		sscanf(record+2, IHEX_SCANWORD, &rec.address);
		sscanf(record+6, IHEX_SCANBYTE, &rec.record_type);
		
		// We have reached the end of the hex file, stop.
		if(rec.record_type == IHEX_EOF)
			break;
		
		// Skip to the data section of the record and read rec.length bytes
		record += 8;
		for(c = 0; c < rec.length; c++) {
			sscanf(record, IHEX_SCANBYTE, &rec.data[c]);
			record += 2;
		}
		
		// Final byte of the record is checksum
		sscanf(record, IHEX_SCANBYTE, &rec.checksum);
		
		// Calculate the checksum...
		// Add all bytes together & 0xFF (restrict to one byte)
		// and find two's complement of it.
		chk = rec.length;
		chk += (rec.address>>8) & 0xFF; // First byte of address
		chk += rec.address & 0xFF; // Second byte
		chk += rec.record_type;http://nite.devtails.com/flicks/w98.jpg
		
		// Add data to our checksum calculation...
		for(c = 0; c < rec.length; c++)
			chk += rec.data[c];
		
		// Take the two's complement and restrict to 1 byte
		chk = ((~chk & 0xFF) + 1) & 0xFF;
		if(chk != rec.checksum) {
			fprintf(stderr, "Error! Parse HEX file: Checksum mismatch "
								 "on line %d - Calculated %02X, Required %02X\n",
								 line, chk, rec.checksum);
			goto error;
		}
		
		// If this is a data record, copy to picmem at the correct addr
		if(rec.record_type == IHEX_DATA) 
			memcpy(picmem+rec.address, rec.data, rec.length);
	}
	#ifdef DEBUG
	for(c = 0; c < PIC_RAM_SIZE; c++) {
		if(!(c % 8)) printf("\n0x%04X:", c);
		if(!(c % 2)) putc(' ', stdout);
		printf("%02X", picmem[c]);
	}
	#endif
	
	return picmem;
	
error:
	free(picmem);
	return NULL;
}