Fix accessing cons by switching to a long

This ensures it has the same size as pointers (64 bits) on amd64, which
fixes the pointer "conversion" and arithmetic in C.

scm/inc/driver.c

@@ -23,30 +23,27 @@
#define MAX_MEMORY (1 << 20)
int scheme_entry(int *memory);
int print_hex(int i) {
	printf("0x%x\n", i);
	return i;
}
void print_value(int *val) {
	if ((*val & fixnum_mask) == fixnum_tag) {
		printf("%d", *val >> fixnum_shift);
	} else if ((*val & char_mask) == char_tag) {
		printf("#\\%c", *val >> char_shift);
	} else if ((*val & boolean_mask) == boolean_tag) {
		printf("#%s", (*val >> boolean_shift) == 1 ? "t" : "f");
	} else if (*val == empty_list) {
typedef long ptr;
ptr scheme_entry(int *heap);
void print_value(ptr val) {
	if ((val & fixnum_mask) == fixnum_tag) {
		printf("%d", (int)val >> fixnum_shift);
	} else if ((val & char_mask) == char_tag) {
		printf("#\\%c", (int)val >> char_shift);
	} else if ((val & boolean_mask) == boolean_tag) {
		printf("#%s", (val >> boolean_shift) == 1 ? "t" : "f");
	} else if (val == empty_list) {
		printf("()");
	} else if ((*val & cons_mask) == cons_tag) {
	} else if ((val & cons_mask) == cons_tag) {
		printf("(");
		printf("?");
		print_value(*(int*)(val-1));
		printf(" ");
		printf("?");
		print_value(*(int*)(val+3));
		printf(")");
	} else {
		printf("\nError: unhandled value: %d 0x%x 0x%p\n", *val, *val, val);
		printf("\nError: unhandled value: %d 0x%x 0x%p\n", (int)val, (int)val, (int*)val);
		exit(1);
	}
}
@@ -58,8 +55,8 @@ int main(int argc, char **argv) {
		exit(1);
	}
	memset(mem, 0, MAX_MEMORY * sizeof(int));
	int val = scheme_entry(mem);
	print_value(&val);
	ptr val = scheme_entry(mem);
	print_value(val);
	printf("\n");
	return 0;
}