gb-emu/src/gbasm/operands.c

#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;
}