Added -l command line argument to specify load address

6502-emu.c

@@ -63,7 +63,7 @@ int hextoint(char *str) {
 
 int main(int argc, char *argv[])
 {
-	int a, x, y, sp, sr, pc;
+	int a, x, y, sp, sr, pc, load_addr;
 	int verbose, interactive, mem_dump;
 	long cycles;
 	int opt;
@@ -72,13 +72,14 @@ int main(int argc, char *argv[])
 	interactive = 0;
 	mem_dump = 0;
 	cycles = 0;
+	load_addr = 0xC000;
 	a = 0;
 	x = 0;
 	y = 0;
 	sp = 0;
 	sr = 0;
 	pc = -RST_VEC;  // negative implies indirect
-	while ((opt = getopt(argc, argv, "vima:x:y:r:p:s:g:c:")) != -1) {
+	while ((opt = getopt(argc, argv, "vima:x:y:r:p:s:g:c:l:")) != -1) {
 		switch (opt) {
 		case 'v':
 			verbose = 1;
@@ -111,6 +112,9 @@ int main(int argc, char *argv[])
 		case 'c':
 			cycles = atol(optarg);
 			break;
+		case 'l':
+			load_addr = hextoint(optarg);
+			break;
 	    default: /* '?' */
 			fprintf(stderr, "Usage: %s [-v] [-i] [-a HEX] [-x HEX] [-y HEX] [-s HEX] [-p HEX] [-g|-r ADDR] file.rom\nThe first 16k of \"file.rom\" is loaded into the last 16k of memory.\n",
 	               argv[0]);
@@ -122,7 +126,7 @@ int main(int argc, char *argv[])
 	   fprintf(stderr, "Expected argument after options\n");
 	   exit(EXIT_FAILURE);
 	}
-	if (load_rom(argv[optind]) != 0) {
+	if (load_rom(argv[optind], load_addr) != 0) {
 		printf("Error loading \"%s\".\n", argv[optind]);
 		return EXIT_FAILURE;
 	}

6502.c

@@ -925,8 +925,10 @@ void reset_cpu(int _a, int _x, int _y, int _sp, int _sr, int _pc)
 	total_cycles = 0;
 }
 
-int load_rom(char * filename)
-{ // TODO allow more flexible loading
+int load_rom(char * filename, int load_addr)
+{
+	int loaded_size, max_size;
+
 	memset(memory, 0, sizeof(memory)); // clear ram first
 	
 	FILE * fp = fopen(filename, "r");
@@ -935,10 +937,9 @@ int load_rom(char * filename)
 		return -1;
 	}
 	
-	if (!fread(&memory[0xC000], 0x4000, 1, fp)) {
-		printf("Error: ROM file too short.\n");
-		return -1;
-	}
+	max_size = 0x10000 - load_addr;
+	loaded_size = (int)fread(&memory[load_addr], 1, (size_t)max_size, fp);
+	fprintf(stderr, "Loaded $%04x bytes: $%04x - $%04x\n", loaded_size, load_addr, load_addr + loaded_size - 1);
 	
 	fclose(fp);
 	return 0;

6502.h

@@ -70,7 +70,7 @@ void init_tables();
 
 void reset_cpu(int _a, int _x, int _y, int _sp, int _sr, int _pc);
 
-int load_rom(char * filename);
+int load_rom(char * filename, int load_addr);
 
 int step_cpu(int verbose);