1 files changed, 97 insertions, 1 deletions
diff --git a/src/orgaemu.c b/src/orgaemu.c
index 00c30cf..be53a22 100644
--- a/src/orgaemu.c
+++ b/src/orgaemu.c
@@ -1,8 +1,104 @@
+#include "drain.h"
+#include "ops.h"
 #include <stdio.h>
+#include <stdint.h>
+
+#define MEM_SIZE 0xffff
+
+static uint16_t *stack = NULL;
+static size_t stack_ptr = 0;
+
+static uint16_t
+get_short(const unsigned char *s)
+{
+	return s[0] | (s[1] * 0x0100);
+}
+
+static void
+push(uint16_t v)
+{
+	stack[stack_ptr] = v;
+	stack_ptr += 1;
+	if (stack_ptr >= MEM_SIZE) {
+		fprintf(stderr, "stack overflow\n");
+		return;
+	}
+}
+
+static uint16_t
+pop(void)
+{
+	if (stack_ptr == 0) {
+		fprintf(stderr, "stack underflow\n");
+		return 0;
+	}
+	stack_ptr -= 1;
+	return stack[stack_ptr];
+}
+ 
+static void
+exec_data(uint16_t *mem)
+{
+	for (long pc = 0; pc < MEM_SIZE; pc++) {
+		switch (mem[pc]) {
+		case OP_NOP:
+			break;
+		case OP_LIT:
+			push(mem[pc + 1]);
+			pc += 1;
+			break;
+		case OP_WRT:
+			putchar(pop());
+			break;
+		case OP_RET:
+			return;
+		default:
+			fprintf(stderr, "unhandled opcode %04x\n", mem[pc]);
+			return;
+		}
+	}
+}
 
 int
 main(int argc, char **argv)
 {
-	(void)argc, (void)argv;
+	if (argc != 2) {
+		fprintf(stderr, "usage: %s <rom>\n", argv[0]);
+		return 1;
+	}
+
+	FILE *file = fopen(argv[1], "rb");
+	if (file == NULL) {
+		perror(argv[1]);
+		return 1;
+	}
+
+	long size;
+	unsigned char *const data = (unsigned char*)drain(file, &size);
+	fclose(file);
+	if (data == NULL)
+		return 1;
+
+	uint16_t *mem = calloc(MEM_SIZE, sizeof(uint16_t));
+	if (mem == NULL) {
+		perror("main:calloc");
+		free(data);
+		return 1;
+	}
+
+	for (long i = 0; i < size; i += 2)
+		mem[i / 2] = get_short(data + i);
+	free(data);
+
+	stack = calloc(MEM_SIZE, sizeof(uint16_t));
+	if (stack == NULL) {
+		perror("main:calloc");
+		free(mem);
+		return 1;
+	}
+
+	exec_data(mem);
+	free(mem);
+	free(stack);
 	return 0;
 }