gb-emu: initial commit

Add a mostly non-functional Gameboy CPU and the skeleton
of a Gameboy assembler intended for unit tests.

src/gbasm/types.h

@@ -0,0 +1,49 @@
+#ifndef GBASM_TYPES_H
+#define GBASM_TYPES_H
+
+#include <stdint.h>
+
+#include "gbasm/gb_types.h"
+#include "gbasm/emitter.h"
+
+struct gbasm_parsed_inst {
+	const char *src_line;
+	const char *file_name;
+	const char *opcode;
+	int line_num;
+
+	struct gbasm_operand operands[GBASM_MAX_OPERANDS];
+	int num_operands;
+};
+
+struct gbasm_op_info {
+	char *opcode;
+	uint32_t operand_types[GBASM_MAX_OPERANDS];
+
+	int (*check)(const struct gbasm_parsed_inst *inst,
+	             const struct gbasm_op_info *op_info);
+	size_t (*length)(const struct gbasm_parsed_inst *inst,
+	                 const struct gbasm_op_info *info);
+	size_t (*emit)(struct emitter *emitter,
+	               const struct gbasm_parsed_inst *inst);
+};
+
+struct gbasm_operand_info {
+	
+	const char *token;
+
+	bool fixed;
+	union {
+		/* Valid iff fixed == true */
+		int (*convert)(const char *token, struct gbasm_operand *operand);
+		/* Valid iff fixed == false */
+		struct gbasm_operand op_info;
+	};
+};
+
+struct gbasm_operand_prefix {
+	const char *prefix;
+	int (*convert)(const char *token, struct gbasm_operand *operand);
+};
+
+#endif