// SPDX-FileCopyrightText: 2015 Felix Held
// SPDX-License-Identifier: BSD-2-Clause

#include <rz_types.h>
#include <rz_util.h>
#include <rz_lib.h>
#include <rz_asm.h>
#include "asm_private.h"
#include "lm32/lm32_isa.h"

#define LM32_UNUSED 0

// str has to be at least 8 chars elements long
static int reg_number_to_string(ut8 reg, char *str) {
	ut8 match_idx = 0xff;
	int i;
	for (i = 0; i < RzAsmLm32RegNumber; i++) {
		if (RzAsmLm32Regs[i].number == reg) {
			match_idx = i;
			break;
		}
	}
	// register number not found in array. this shouldn't happen
	if (match_idx == 0xff) {
		return -1;
	}
	strcpy(str, RzAsmLm32Regs[match_idx].name);
	return 0;
}

#if LM32_UNUSED
static int string_to_reg_number(const char *str, ut8 *num) {
	ut8 match_idx = 0xff;
	int i;
	for (i = 0; i < RzAsmLm32RegNumber; i++) {
		if (!strcmp(RzAsmLm32Regs[i].name, str)) {
			match_idx = i;
			break;
		}
	}
	// register name string not found in array
	if (match_idx == 0xff)
		return -1;
	*num = RzAsmLm32Regs[match_idx].number;
	return 0;
}

static int string_to_csr_number(const char *str, ut8 *num) {
	ut8 match_idx = 0xff;
	int i;
	for (i = 0; i < RzAsmLm32CsrNumber; i++) {
		if (!strcmp(RzAsmLm32Csrs[i].name, str)) {
			match_idx = i;
			break;
		}
	}
	// csr name string not found in array
	if (match_idx == 0xff)
		return -1;
	*num = RzAsmLm32Csrs[match_idx].number;
	return 0;
}

static int string_to_opcode(const char *str, ut8 *num) {
	ut8 tmp_num = 0xff;
	int i;
	for (i = 0; i < RzAsmLm32OpcodeNumber; i++) {
		if (!strcmp(RzAsmLm32OpcodeList[i].name, str)) {
			tmp_num = i;
		}
	}
	// string not found in array
	if (tmp_num == 0xff)
		return -1;
	*num = tmp_num;
	return 0;
}
#endif

// str has to be at least 8 chars elements long
static int csr_number_to_string(ut8 csr, char *str) {
	ut8 match_idx = 0xff;
	int i;
	for (i = 0; i < RzAsmLm32CsrNumber; i++) {
		if (RzAsmLm32Csrs[i].number == csr) {
			match_idx = i;
			break;
		}
	}
	// csr number not found in array
	if (match_idx == 0xff) {
		return -1;
	}
	strcpy(str, RzAsmLm32Csrs[match_idx].name);
	return 0;
}

// sign_loc is the location of the sign bit before the shift
static st32 shift_and_signextend(ut8 shift, ut8 sign_loc, ut32 val) {
	ut32 tmp = val << shift;
	if (tmp & (1 << (shift + sign_loc))) {
		tmp |= ~((1 << (shift + sign_loc + 1)) - 1);
	}
	return tmp;
}

static bool is_invalid_imm5_instr(RzAsmLm32Instruction *instr) {
	return instr->value & RzAsmLm32InstrImm5InvalidBitsMask;
}

static bool is_invalid_one_reg_instr(RzAsmLm32Instruction *instr) {
	return instr->value & RzAsmLm32InstrOneRegInvalidBitsMask;
}

static bool is_invalid_two_reg_instr(RzAsmLm32Instruction *instr) {
	return instr->value & RzAsmLm32InstrTwoRegsInvalidBitsMask;
}

static bool is_invalid_wcsr_instr(RzAsmLm32Instruction *instr) {
	return instr->value & RzAsmLm32InstrWcsrInvalidBitsMask;
}

// ret == b ra
static bool is_pseudo_instr_ret(RzAsmLm32Instruction *instr) {
	//"ra" == 0x1d
	return (instr->op == lm32_op_b) && (instr->src0_reg == 0x1d);
}

// mv rX, rY == or rX, rY, r0
static bool is_pseudo_instr_mv(RzAsmLm32Instruction *instr) {
	return (instr->op == lm32_op_or) && !instr->src1_reg;
}

// mvhi rX, imm16 == orhi rX, r0, imm16
static bool is_pseudo_instr_mvhi(RzAsmLm32Instruction *instr) {
	return (instr->op == lm32_op_orhi) && !instr->src0_reg;
}

// not rX, rY == xnor rX, rY, r0
static bool is_pseudo_instr_not(RzAsmLm32Instruction *instr) {
	return (instr->op == lm32_op_xnor) && !instr->src1_reg;
}

// mvi rX, imm16 == addi rX, r0, imm16
static bool is_pseudo_instr_mvi(RzAsmLm32Instruction *instr) {
	return (instr->op == lm32_op_addi) && !instr->src0_reg;
}

// nop == addi r0, r0, 0
static bool is_pseudo_instr_nop(RzAsmLm32Instruction *instr) {
	return (instr->op == lm32_op_addi) && !instr->dest_reg &&
		!instr->src0_reg && !instr->immediate;
}

// raise instruction is used for break, scall
static bool is_pseudo_instr_raise(RzAsmLm32Instruction *instr) {
	return instr->op == raise_instr;
}

static int rz_asm_lm32_decode(RzAsmLm32Instruction *instr) {
	instr->op = extract_opcode(instr->value);
	if (instr->op >= RzAsmLm32OpcodeNumber) {
		return -1;
	}
	instr->op_decode = RzAsmLm32OpcodeList[instr->op];

	switch (instr->op_decode.type) {
	case reg_imm16_signextend:
		instr->dest_reg = extract_reg_v(instr->value);
		instr->src0_reg = extract_reg_u(instr->value);
		instr->immediate = shift_and_signextend(0, RzAsmLm32Imm16SignBitPos,
			extract_imm16(instr->value));
		break;
	case reg_imm16_shift2_signextend:
		instr->dest_reg = extract_reg_v(instr->value);
		instr->src0_reg = extract_reg_u(instr->value);
		instr->immediate = shift_and_signextend(2, RzAsmLm32Imm16SignBitPos,
			extract_imm16(instr->value));
		break;
	case reg_imm16_zeroextend:
		instr->dest_reg = extract_reg_v(instr->value);
		instr->src0_reg = extract_reg_u(instr->value);
		instr->immediate = extract_imm16(instr->value);
		break;
	case reg_imm5:
		if (is_invalid_imm5_instr(instr)) {
			return -1;
		}
		instr->dest_reg = extract_reg_v(instr->value);
		instr->src0_reg = extract_reg_u(instr->value);
		instr->immediate = extract_imm5(instr->value);
		break;
	case raise_instr:
		if (is_invalid_imm5_instr(instr)) {
			return -1;
		}
		// might be less bits used, but this shouldn't hurt
		// invalid parameters are caught in print_pseudo_instruction anyway
		instr->immediate = extract_imm5(instr->value);
		break;
	case one_reg:
		if (is_invalid_one_reg_instr(instr)) {
			return -1;
		}
		instr->src0_reg = extract_reg_u(instr->value);
		break;
	case two_regs:
		if (is_invalid_two_reg_instr(instr)) {
			return -1;
		}
		instr->dest_reg = extract_reg_w(instr->value);
		instr->src0_reg = extract_reg_u(instr->value);
		break;
	case three_regs:
		instr->dest_reg = extract_reg_w(instr->value);
		instr->src0_reg = extract_reg_v(instr->value);
		instr->src1_reg = extract_reg_u(instr->value);
		break;
	case reg_csr: // wcsr
		if (is_invalid_wcsr_instr(instr)) {
			return -1;
		}
		instr->src0_reg = extract_reg_v(instr->value);
		instr->csr = extract_reg_u(instr->value);
		break;
	case csr_reg: // rcsr
		// bitmask is the same as the two register one
		if (is_invalid_two_reg_instr(instr)) {
			return -1;
		}
		instr->dest_reg = extract_reg_w(instr->value);
		instr->csr = extract_reg_u(instr->value);
		break;
	case imm26:
		instr->immediate = shift_and_signextend(2, RzAsmLm32Imm26SignBitPos,
			extract_imm26(instr->value));
		break;
	case reserved:
	default:
		return -1;
	}

	// see if the instruction corresponds to a pseudo-instruction
	instr->pseudoInstruction = is_pseudo_instr_ret(instr) || is_pseudo_instr_mv(instr) ||
		is_pseudo_instr_mvhi(instr) || is_pseudo_instr_not(instr) || is_pseudo_instr_mvi(instr) ||
		is_pseudo_instr_nop(instr) || is_pseudo_instr_raise(instr);

	return 0;
}

static int write_reg_names_to_struct(RzAsmLm32Instruction *instr) {
	switch (instr->op_decode.type) {
	case reg_imm16_signextend:
	case reg_imm16_shift2_signextend:
	case reg_imm16_zeroextend:
	case reg_imm5:
	case two_regs:
		if (reg_number_to_string(instr->dest_reg, instr->dest_reg_str)) {
			return -1;
		}
		if (reg_number_to_string(instr->src0_reg, instr->src0_reg_str)) {
			return -1;
		}
		break;
	case one_reg:
		if (reg_number_to_string(instr->src0_reg, instr->src0_reg_str)) {
			return -1;
		}
		break;
	case three_regs:
		if (reg_number_to_string(instr->dest_reg, instr->dest_reg_str)) {
			return -1;
		}
		if (reg_number_to_string(instr->src0_reg, instr->src0_reg_str)) {
			return -1;
		}
		if (reg_number_to_string(instr->src1_reg, instr->src1_reg_str)) {
			return -1;
		}
		break;
	case reg_csr:
		if (reg_number_to_string(instr->src0_reg, instr->src0_reg_str)) {
			return -1;
		}
		if (csr_number_to_string(instr->csr, instr->csr_reg_str)) {
			return -1;
		}
		break;
	case csr_reg:
		if (reg_number_to_string(instr->dest_reg, instr->dest_reg_str)) {
			return -1;
		}
		if (csr_number_to_string(instr->csr, instr->csr_reg_str)) {
			return -1;
		}
		break;
	case raise_instr:
	case imm26:
		break;
	default:
		return -1;
	}
	return 0;
}

static int print_pseudo_instruction(RzAsmLm32Instruction *instr, char *str) {
	if (!instr->pseudoInstruction) {
		return -1;
	}
	switch (instr->op) {
	// ret == b ra
	case lm32_op_b:
		strcpy(str, "ret");
		break;
	// mv rX, rY == or rX, rY, r0
	case lm32_op_or:
		sprintf(str, "mv %s, %s", instr->dest_reg_str, instr->src0_reg_str);
		break;
	// mvhi rX, imm16 == orhi rX, r0, imm16
	case lm32_op_orhi:
		sprintf(str, "mvhi %s, 0x%x", instr->dest_reg_str, instr->immediate);
		break;
	// not rX, rY == xnor rX, rY, r0
	case lm32_op_xnor:
		sprintf(str, "not %s, %s", instr->dest_reg_str, instr->src0_reg_str);
		break;
	// mvi rX, imm16 == addi rX, r0, imm16
	// nop == addi r0, r0, 0
	case lm32_op_addi:
		if (is_pseudo_instr_nop(instr)) { // nop
			strcpy(str, "nop");
		} else { // mvi
			sprintf(str, "mvi %s, 0x%x", instr->dest_reg_str, instr->immediate);
		}
		break;
	// break, scall
	case lm32_op_raise:
		switch (instr->immediate) {
		case 0x2: // break
			strcpy(str, "break");
			break;
		case 0x7: // scall
			strcpy(str, "scall");
			break;
		default:
			return -1;
		}
		break;
	default:
		return -1;
	}
	return 0;
}

static int rz_asm_lm32_stringify(RzAsmLm32Instruction *instr, char *str) {
	if (write_reg_names_to_struct(instr)) {
		return -1;
	}

	// pseudo instructions need some special handling
	if (instr->pseudoInstruction) {
		// return after printing the decoded pseudo instruction, so it doesn't get overwritten
		return print_pseudo_instruction(instr, str);
	}

	// get opcode string
	strcpy(str, instr->op_decode.name);

	// get parameters (registers, immediate) string
	switch (instr->op_decode.type) {
	case reg_imm16_signextend:
		sprintf(str, "%s %s, %s, 0x%x", instr->op_decode.name, instr->dest_reg_str, instr->src0_reg_str,
			instr->immediate);
		break;
	case reg_imm16_zeroextend:
	case reg_imm5:
		sprintf(str, "%s %s, %s, 0x%x", instr->op_decode.name, instr->dest_reg_str, instr->src0_reg_str,
			instr->immediate);
		break;
	case reg_imm16_shift2_signextend:
		// print the branch/call destination address
		sprintf(str, "%s %s, %s, 0x%x", instr->op_decode.name, instr->dest_reg_str, instr->src0_reg_str,
			instr->immediate + instr->addr);
		break;
	case one_reg:
		sprintf(str, "%s %s", instr->op_decode.name, instr->src0_reg_str);
		break;
	case two_regs:
		sprintf(str, "%s %s, %s", instr->op_decode.name, instr->dest_reg_str, instr->src0_reg_str);
		break;
	case three_regs:
		sprintf(str, "%s %s, %s, %s", instr->op_decode.name, instr->dest_reg_str, instr->src0_reg_str,
			instr->src1_reg_str);
		break;
	case reg_csr:
		sprintf(str, "%s %s, %s", instr->op_decode.name, instr->csr_reg_str, instr->src0_reg_str);
		break;
	case csr_reg:
		sprintf(str, "%s %s, %s", instr->op_decode.name, instr->dest_reg_str, instr->csr_reg_str);
		break;
	case imm26:
		// print the branch/call destination address
		sprintf(str, "%s 0x%x", instr->op_decode.name, instr->immediate + instr->addr);
		break;
	// case raise_instr: //unneeded; handled as pseudo instruction
	default:
		return -1;
	}
	return 0;
}

static int disassemble(const RzAsm *a, RzAsmOp *op, const ut8 *buf, int len) {
	RzAsmLm32Instruction instr = { 0 };
	instr.value = buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
	instr.addr = a->pc;
	if (rz_asm_lm32_decode(&instr)) {
		rz_strbuf_set(&op->buf_asm, "invalid");
		return -1;
	}
	// op->buf_asm is 256 chars long, which is more than sufficient
	if (rz_asm_lm32_stringify(&instr, rz_strbuf_get(&op->buf_asm))) {
		rz_strbuf_set(&op->buf_asm, "invalid");
		return -1;
	}
	return 4;
}

RzAsmPlugin rz_asm_plugin_lm32 = {
	.name = "lm32",
	.arch = "lm32",
	.desc = "Lattice Micro 32 ISA disassembler",
	.author = "Felix Held",
	.license = "BSD",
	.bits = 32,
	.endian = RZ_SYS_ENDIAN_BIG,
	.disassemble = &disassemble,
};
