gb-emu: initial commit

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

src/gbasm/operands.c

@@ -0,0 +1,212 @@
+#include "gbasm/gb_types.h"
+#include "gbasm/opcodes.h"
+#include "gbasm/errors.h"
+
+#include "tri.h"
+#include "common.h"
+
+#include <string.h>
+
+static bool operands_initted = false;
+static struct tri operand_tri;
+static struct tri prefixes_tri;
+
+static const struct gbasm_operand_info gbasm_operand_infos[] = {
+	{
+		.token = "a",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_REG_8,
+			.r8 = { .type = GBASM_OPERAND_R8_A },
+		}
+	},
+	{
+		.token = "b",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_REG_8,
+			.r8 = { .type = GBASM_OPERAND_R8_B },
+		},
+	},
+	{
+		/* TODO: handle C condition code */
+		.token = "c",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_REG_8,
+			.r8 = { .type = GBASM_OPERAND_R8_C },
+		},
+	},
+	{
+		.token = "d",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_REG_8,
+			.r8 = { .type = GBASM_OPERAND_R8_D },
+		},
+	},
+	{
+		.token = "e",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_REG_8,
+			.r8 = { .type = GBASM_OPERAND_R8_E },
+		},
+	},
+	{
+		.token = "h",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_REG_8,
+			.r8 = { .type = GBASM_OPERAND_R8_H },
+		},
+	},
+	{
+		.token = "l",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_REG_8,
+			.r8 = { .type = GBASM_OPERAND_R8_L },
+		},
+	},
+	{
+		.token = "bc",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_REG_16,
+			.r16 = { GBASM_OPERAND_R16_BC },
+		},
+	},
+	{
+		.token = "de",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_REG_16,
+			.r16 = { GBASM_OPERAND_R16_DE },
+		},
+	},
+	{
+		.token = "hl",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_REG_16,
+			.r16 = { GBASM_OPERAND_R16_HL },
+		},
+	},
+	{
+		.token = "(hl)",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_REG_16,
+			.r16 = { GBASM_OPERAND_R16_HL_DEREF },
+		},
+	},
+
+	{
+		.token = "sp",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_REG_16,
+			.r16 = { GBASM_OPERAND_R16_SP },
+		},
+	},
+	{
+		.token = "nc",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_COND,
+			.cond = { GBASM_OPERAND_COND_NC },
+		},
+	},
+	{
+		.token = "z",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_COND,
+			.cond = { GBASM_OPERAND_COND_Z },
+		},
+	},
+	{
+		.token = "nz",
+		.fixed = true,
+		.op_info = {
+			.type = GBASM_OPERAND_COND,
+			.cond = { GBASM_OPERAND_COND_NZ },
+		},
+	},
+};
+
+static int convert_constant(const char *token, struct gbasm_operand *info)
+{
+	int val = strtol(token + 1, NULL, 0);
+
+	if (val <= 0xff || val >= -0xff) {
+		info->type = GBASM_OPERAND_IMM_8;
+		info->d8.value = val;
+	} else if (val <= 0xffff || val >= 0xffff) {
+		info->type = GBASM_OPERAND_IMM_16;
+		info->d16.value = val;
+	} else {
+		return -1;
+	}
+
+	return 0;
+}
+
+static const struct gbasm_operand_prefix prefixes[] = {
+	{
+		.prefix = "$",
+		.convert = convert_constant,
+	},
+};
+
+static void init_opcode_tri()
+{
+	int i;
+
+	tri_init(&operand_tri);
+	tri_init(&prefixes_tri);
+	
+	for (i = 0; i < ARRAY_SIZE(gbasm_operand_infos); i++) {
+		tri_add_string(&operand_tri,
+		               gbasm_operand_infos[i].token,
+		               (void *) &gbasm_operand_infos[i]);
+	}
+
+	for (i = 0; i < ARRAY_SIZE(prefixes); i++) {
+		tri_add_string(&prefixes_tri,
+		               prefixes[i].prefix,
+		               (void *) &prefixes[i]);
+	}
+		
+	operands_initted = true;
+
+}
+
+int gbasm_parse_operand(const char *token, struct gbasm_operand *out)
+{
+	struct gbasm_operand_info *info;
+	struct gbasm_operand_prefix *prefix;
+	
+	if (!operands_initted) {
+		init_opcode_tri();
+	}
+
+	info = (struct gbasm_operand_info *) tri_get_string(&operand_tri, token);
+	if (info != NULL) {
+		if (info->fixed) {
+			memcpy(out, &info->op_info, sizeof(*out));
+		} else {
+			info->convert(token, out);
+		}
+		return 0;
+	}
+
+	prefix = (struct gbasm_operand_prefix *) tri_prefix_match(&prefixes_tri, token);
+	if (prefix != NULL) {
+		prefix->convert(token, out);
+		return 0;
+	}
+	
+	return -1;
+}