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emu/riscv64.cc

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// https://docs.riscv.org/reference/isa/unpriv/rv-32-64g.html
// https://riscv.org/wp-content/uploads/2024/12/riscv-calling.pdf
#if !defined(__cplusplus) || __cplusplus < 202302L
#error "C++23 or later is required. Either get a newer compiler " \
"or manually edit this file to include fmtlib (https://github.com/fmtlib/fmt) " \
"instead of <print> and remove this check."
#endif
#include <cstring>
#include <fstream>
#include <gelf.h>
#include <iostream>
#include <libelf.h>
#include <print>
#include <vector>
using i8 = int8_t;
using i16 = int16_t;
using i32 = int32_t;
using i64 = int64_t;
using u8 = uint8_t;
using u16 = uint16_t;
using u32 = uint32_t;
using u64 = uint64_t;
static_assert(sizeof(size_t) == sizeof(u64), "u64 must be 64-bit");
static_assert(std::endian::native == std::endian::little,
"Big endianness not supported");
static constexpr u64 MEMORY_SIZE = 20 * 1024 * 1024; // should be enough
static constexpr std::array<const char *, 32> REGS = {
"zero", "ra", "sp", "gp", "tp", "t0", "t1", "t2", "fp", "s1", "a0",
"a1", "a2", "a3", "a4", "a5", "a6", "a7", "s2", "s3", "s4", "s5",
"s6", "s7", "s8", "s9", "s10", "s11", "t3", "t4", "t5", "t6"};
enum Op {
INVALID,
ADD,
ADDI,
ADDIW,
ADDW,
AND,
ANDI,
AUIPC,
BEQ,
BGE,
BGEU,
BLT,
BLTU,
BNE,
DIV,
DIVU,
DIVUW,
DIVW,
ECALL,
JAL,
JALR,
LB,
LBU,
LD,
LH,
LHU,
LUI,
LW,
LWU,
MUL,
MULH,
MULHU,
MULW,
OR,
ORI,
REM,
REMU,
REMUW,
REMW,
SB,
SD,
SH,
SLL,
SLLI,
SLLIW,
SLLW,
SLT,
SLTI,
SLTIU,
SLTU,
SRA,
SRAI,
SRAIW,
SRAW,
SRL,
SRLI,
SRLIW,
SRLW,
SUB,
SUBW,
SW,
XOR,
XORI
};
struct Ins {
Op op;
u8 rd;
u8 funct3;
u8 rs1;
u8 rs2;
u8 funct7;
u8 shamt;
u8 funct6;
i32 imm;
};
struct Section {
u64 offset;
u64 size;
u64 entrypoint;
};
enum class Format { NONE, R, I, I_LOAD, I_SHIFT, S, B, U, J };
struct OpDef {
const char *mnemonic;
Format format;
};
static constexpr std::array<OpDef, 63> OP_TABLE = {{
{"???", Format::NONE}, {"add", Format::R},
{"addi", Format::I}, {"addiw", Format::I},
{"addw", Format::R}, {"and", Format::R},
{"andi", Format::I}, {"auipc", Format::U},
{"beq", Format::B}, {"bge", Format::B},
{"bgeu", Format::B}, {"blt", Format::B},
{"bltu", Format::B}, {"bne", Format::B},
{"div", Format::R}, {"divu", Format::R},
{"divuw", Format::R}, {"divw", Format::R},
{"ecall", Format::NONE}, {"jal", Format::J},
{"jalr", Format::I}, {"lb", Format::I_LOAD},
{"lbu", Format::I_LOAD}, {"ld", Format::I_LOAD},
{"lh", Format::I_LOAD}, {"lhu", Format::I_LOAD},
{"lui", Format::U}, {"lw", Format::I_LOAD},
{"lwu", Format::I_LOAD}, {"mul", Format::R},
{"mulh", Format::R}, {"mulhu", Format::R},
{"mulw", Format::R}, {"or", Format::R},
{"ori", Format::I}, {"rem", Format::R},
{"remu", Format::R}, {"remuw", Format::R},
{"remw", Format::R}, {"sb", Format::S},
{"sd", Format::S}, {"sh", Format::S},
{"sll", Format::R}, {"slli", Format::I_SHIFT},
{"slliw", Format::I_SHIFT}, {"sllw", Format::R},
{"slt", Format::R}, {"slti", Format::I},
{"sltiu", Format::I}, {"sltu", Format::R},
{"sra", Format::R}, {"srai", Format::I_SHIFT},
{"sraiw", Format::I_SHIFT}, {"sraw", Format::R},
{"srl", Format::R}, {"srli", Format::I_SHIFT},
{"srliw", Format::I_SHIFT}, {"srlw", Format::R},
{"sub", Format::R}, {"subw", Format::R},
{"sw", Format::S}, {"xor", Format::R},
{"xori", Format::I},
}};
class RISCV64 {
public:
RISCV64(const std::vector<char> &exe_bytes) {
Elf *elf =
elf_memory(const_cast<char *>(exe_bytes.data()), exe_bytes.size());
GElf_Ehdr ehdr;
gelf_getehdr(elf, &ehdr);
m_code_section = get_code_section(elf, ehdr);
m_pc = m_code_section.offset;
for (u64 i = 0; i < ehdr.e_phnum; i++) {
GElf_Phdr phdr;
gelf_getphdr(elf, i, &phdr);
if (phdr.p_type == PT_LOAD) {
std::copy_n(exe_bytes.data() + phdr.p_offset, phdr.p_filesz,
m_memory.data() + phdr.p_vaddr);
}
}
elf_end(elf);
u64 num_ins = m_code_section.size / 4;
m_decoded.resize(num_ins);
for (u64 i = 0; i < num_ins; i++) {
u32 raw;
std::memcpy(&raw, m_memory.data() + m_code_section.offset + i * 4,
sizeof(raw));
m_decoded[i] = decode_raw(raw);
}
}
void disassemble_all() {
for (m_pc = m_code_section.offset;
m_pc < m_code_section.offset + m_code_section.size; m_pc += 4) {
disassemble_one();
}
}
void disassemble_one() {
Ins ins = m_decoded[(m_pc - m_code_section.offset) / 4];
const OpDef &def = OP_TABLE[ins.op];
switch (def.format) {
case Format::R:
std::println("{} {}, {}, {}", def.mnemonic, REGS[ins.rd], REGS[ins.rs1],
REGS[ins.rs2]);
break;
case Format::I:
std::println("{} {}, {}, {}", def.mnemonic, REGS[ins.rd], REGS[ins.rs1],
ins.imm);
break;
case Format::I_LOAD:
std::println("{} {}, {}({})", def.mnemonic, REGS[ins.rd], ins.imm,
REGS[ins.rs1]);
break;
case Format::I_SHIFT:
std::println("{} {}, {}, {}", def.mnemonic, REGS[ins.rd], REGS[ins.rs1],
ins.shamt);
break;
case Format::U:
std::println("{} {}, {}", def.mnemonic, REGS[ins.rd], ins.imm);
break;
case Format::S:
std::println("{} {}, {}({})", def.mnemonic, REGS[ins.rs2], ins.imm,
REGS[ins.rs1]);
break;
case Format::B:
std::println("{} {}, {}, {}", def.mnemonic, REGS[ins.rs1], REGS[ins.rs2],
ins.imm);
break;
case Format::J:
std::println("{} {}, {}", def.mnemonic, REGS[ins.rd], ins.imm);
break;
case Format::NONE:
std::println("{}", def.mnemonic);
break;
}
}
void dump() {
std::print("REGS:");
for (u64 i = 0; i < 32; i++) {
std::print(" {}", m_regs[i]);
}
std::println();
}
void execute() {
m_pc = m_code_section.entrypoint;
m_regs[2] = MEMORY_SIZE - 1024; // set the stack pointer
while (m_pc < m_code_section.offset + m_code_section.size) {
m_regs[0] = 0; // clear the zero register
Ins i = m_decoded[(m_pc - m_code_section.offset) / 4];
switch (i.op) {
case Op::INVALID: {
std::println(stderr, "Tried to execute Op::INVALID");
exit(1);
}; break;
case Op::ADD: {
m_regs[i.rd] = m_regs[i.rs1] + m_regs[i.rs2];
}; break;
case Op::ADDI: {
m_regs[i.rd] = m_regs[i.rs1] + i.imm;
}; break;
case Op::ADDIW: {
m_regs[i.rd] = (i32)m_regs[i.rs1] + (i32)i.imm;
}; break;
case Op::ADDW: {
m_regs[i.rd] = (i32)(m_regs[i.rs1] + m_regs[i.rs2]);
}; break;
case Op::AND: {
m_regs[i.rd] = m_regs[i.rs1] & m_regs[i.rs2];
}; break;
case Op::ANDI: {
std::println(stderr, "ANDI unimplemented");
exit(1);
}; break;
case Op::AUIPC: {
m_regs[i.rd] = m_pc + ((i64)i.imm << 12);
}; break;
case Op::BEQ: {
if (m_regs[i.rs1] == m_regs[i.rs2]) {
m_pc += i.imm;
continue;
}
}; break;
case Op::BGE: {
if (m_regs[i.rs1] >= m_regs[i.rs2]) {
m_pc += i.imm;
continue;
}
}; break;
case Op::BGEU: {
std::println(stderr, "BGEU unimplemented");
exit(1);
}; break;
case Op::BLT: {
if (m_regs[i.rs1] < m_regs[i.rs2]) {
m_pc += i.imm;
continue;
}
}; break;
case Op::BLTU: {
if ((u64)m_regs[i.rs1] < (u64)m_regs[i.rs2]) {
m_pc += i.imm;
continue;
}
}; break;
case Op::BNE: {
if (m_regs[i.rs1] != m_regs[i.rs2]) {
m_pc += i.imm;
continue;
}
}; break;
case Op::DIV: {
if (m_regs[i.rs2] == 0) {
m_regs[i.rd] = -1;
} else {
m_regs[i.rd] = m_regs[i.rs1] / m_regs[i.rs2];
}
}; break;
case Op::DIVU: {
std::println(stderr, "DIVU unimplemented");
exit(1);
}; break;
case Op::DIVUW: {
if (m_regs[i.rs2] == 0) {
m_regs[i.rd] = -1LL;
} else {
m_regs[i.rd] = (i32)((u32)m_regs[i.rs1] / (u32)m_regs[i.rs2]);
}
}; break;
case Op::DIVW: {
if (m_regs[i.rs2] == 0) {
m_regs[i.rd] = (u64)(i64)(-1);
} else {
m_regs[i.rd] = (i64)(m_regs[i.rs1] / m_regs[i.rs2]);
}
}; break;
case Op::ECALL: {
// https://jborza.com/post/2021-05-11-riscv-linux-syscalls/
switch (m_regs[17]) {
case 63: { // read
if (m_regs[10] != 0) {
std::println(stderr, "read syscall implemented only for stdin.");
exit(1);
}
u64 start = m_regs[11];
u64 count = m_regs[12];
u64 bytes_read = 0;
for (u64 i = 0; i < count; i++) {
char c;
if (!std::cin.get(c))
break;
m_memory[start + i] = (u8)c;
bytes_read++;
if (c == '\n')
break;
}
m_regs[10] = bytes_read;
}; break;
case 64: { // write
if (m_regs[10] != 1) {
std::println(stderr, "write syscall implemented only for stdout.");
exit(1);
}
u64 start = m_regs[11];
u64 end = m_regs[11] + m_regs[12];
for (u64 i = start; i < end; i++) {
std::cout.put(m_memory[i]);
}
}; break;
case 93: { // exit
std::println("Program exited with code {}.", m_regs[10]);
return;
}; break;
case 169: { // gettimeofday
// TODO: actually return the time
i64 tv_addr = m_regs[10];
i64 tz_addr = m_regs[11];
u8 tv_buf[16] = {
0xD2, 0x02, 0x96, 0x49,
0x00, 0x00, 0x00, 0x00, // tv_sec = 1234567890
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, // tv_usec = 0
};
memcpy(&m_memory[tv_addr], tv_buf, 16);
memset(&m_memory[tz_addr], 0, 8);
m_regs[10] = 0;
}; break;
default:
std::println(stderr, "Unimplemented syscall: {}", m_regs[17]);
exit(1);
}
}; break;
case Op::JAL: {
m_regs[i.rd] = m_pc + 4;
m_pc += i.imm;
continue;
}; break;
case Op::JALR: {
u64 target = (m_regs[i.rs1] + i.imm) & ~(u64)1;
m_regs[i.rd] = m_pc + 4;
m_pc = target;
continue;
}; break;
case Op::LB: {
m_regs[i.rd] = (i8)m_memory[m_regs[i.rs1] + i.imm];
}; break;
case Op::LBU: {
m_regs[i.rd] = m_memory[m_regs[i.rs1] + i.imm];
}; break;
case Op::LD: {
m_regs[i.rd] = *(u64 *)&m_memory[m_regs[i.rs1] + i.imm];
}; break;
case Op::LH: {
m_regs[i.rd] = *(i16 *)&m_memory[m_regs[i.rs1] + i.imm];
}; break;
case Op::LHU: {
std::println(stderr, "LHU unimplemented");
exit(1);
}; break;
case Op::LUI: {
m_regs[i.rd] = (i64)(i32)(i.imm << 12);
}; break;
case Op::LW: {
m_regs[i.rd] = *(i32 *)&m_memory[m_regs[i.rs1] + i.imm];
}; break;
case Op::LWU: {
std::println(stderr, "LWU unimplemented");
exit(1);
}; break;
case Op::MUL: {
m_regs[i.rd] = m_regs[i.rs1] * m_regs[i.rs2];
}; break;
case Op::MULH: {
i64 a_hi = m_regs[i.rs1] >> 32;
i64 b_hi = m_regs[i.rs2] >> 32;
u64 a_lo = (u32)m_regs[i.rs1];
u64 b_lo = (u32)m_regs[i.rs2];
u64 p0 = a_lo * b_lo;
i64 p1 = a_hi * b_lo;
i64 p2 = b_hi * a_lo;
i64 p3 = a_hi * b_hi;
i64 carry = (p0 >> 32);
i64 mid = p1 + p2 + carry;
m_regs[i.rd] = p3 + (mid >> 32);
}; break;
case Op::MULHU: {
u64 a = m_regs[i.rs1];
u64 b = m_regs[i.rs2];
u64 a_lo = a & 0xffffffff;
u64 a_hi = a >> 32;
u64 b_lo = b & 0xffffffff;
u64 b_hi = b >> 32;
u64 lo_lo = a_lo * b_lo;
u64 hi_lo = a_hi * b_lo;
u64 lo_hi = a_lo * b_hi;
u64 hi_hi = a_hi * b_hi;
u64 mid = (lo_lo >> 32) + (hi_lo & 0xffffffff) + (lo_hi & 0xffffffff);
m_regs[i.rd] = hi_hi + (hi_lo >> 32) + (lo_hi >> 32) + (mid >> 32);
}; break;
case Op::MULW: {
m_regs[i.rd] = (i32)(m_regs[i.rs1] * m_regs[i.rs2]);
}; break;
case Op::OR: {
m_regs[i.rd] = m_regs[i.rs1] | m_regs[i.rs2];
}; break;
case Op::ORI: {
std::println(stderr, "ORI unimplemented");
exit(1);
}; break;
case Op::REM: {
if (m_regs[i.rs2] == 0) {
m_regs[i.rd] = m_regs[i.rs1];
} else {
m_regs[i.rd] = m_regs[i.rs1] % m_regs[i.rs2];
}
}; break;
case Op::REMU: {
if (m_regs[i.rs2] == 0) {
m_regs[i.rd] = m_regs[i.rs1];
} else {
m_regs[i.rd] = (u64)m_regs[i.rs1] % (u64)m_regs[i.rs2];
}
}; break;
case Op::REMUW: {
if (m_regs[i.rs2] == 0) {
m_regs[i.rd] = (i32)m_regs[i.rs1];
} else {
m_regs[i.rd] = (i32)((u32)m_regs[i.rs1] % (u32)m_regs[i.rs2]);
}
}; break;
case Op::REMW: {
std::println(stderr, "REMW unimplemented");
exit(1);
}; break;
case Op::SB: {
u64 addr = m_regs[i.rs1] + i.imm;
m_memory[addr] = m_regs[i.rs2];
}; break;
case Op::SD: {
u64 addr = m_regs[i.rs1] + i.imm;
*(u64 *)(&m_memory[addr]) = m_regs[i.rs2];
}; break;
case Op::SH: {
u64 addr = m_regs[i.rs1] + i.imm;
*(u16 *)(&m_memory[addr]) = m_regs[i.rs2];
}; break;
case Op::SLL: {
std::println(stderr, "SLL unimplemented");
exit(1);
}; break;
case Op::SLLI: {
m_regs[i.rd] = m_regs[i.rs1] << i.shamt;
}; break;
case Op::SLLIW: {
m_regs[i.rd] = (i32)m_regs[i.rs1] << i.shamt;
}; break;
case Op::SLLW: {
m_regs[i.rd] =
(i32)(u32)((u32)m_regs[i.rs1] << ((u32)m_regs[i.rs2] & 0b11111));
}; break;
case Op::SLT: {
m_regs[i.rd] = (m_regs[i.rs1] < m_regs[i.rs2]) ? 1 : 0;
}; break;
case Op::SLTI: {
std::println(stderr, "SLTI unimplemented");
exit(1);
}; break;
case Op::SLTIU: {
m_regs[i.rd] = ((u64)m_regs[i.rs1] < (u64)(i64)i.imm) ? 1 : 0;
}; break;
case Op::SLTU: {
m_regs[i.rd] = ((u64)m_regs[i.rs1] < (u64)m_regs[i.rs2]) ? 1 : 0;
}; break;
case Op::SRA: {
std::println(stderr, "SRA unimplemented");
exit(1);
}; break;
case Op::SRAI: {
m_regs[i.rd] = (i64)m_regs[i.rs1] >> i.shamt;
}; break;
case Op::SRAIW: {
m_regs[i.rd] = (i32)m_regs[i.rs1] >> i.shamt;
}; break;
case Op::SRAW: {
m_regs[i.rd] = ((i32)m_regs[i.rs1]) >> ((u32)m_regs[i.rs2] & 0b11111);
}; break;
case Op::SRL: {
std::println(stderr, "SRL unimplemented");
exit(1);
}; break;
case Op::SRLI: {
m_regs[i.rd] = (u64)m_regs[i.rs1] >> i.shamt;
}; break;
case Op::SRLIW: {
m_regs[i.rd] = (i32)((u32)m_regs[i.rs1] >> i.shamt);
}; break;
case Op::SRLW: {
m_regs[i.rd] =
(i32)((u32)m_regs[i.rs1] >> ((u32)m_regs[i.rs2] & 0b11111));
}; break;
case Op::SUB: {
m_regs[i.rd] = m_regs[i.rs1] - m_regs[i.rs2];
}; break;
case Op::SUBW: {
m_regs[i.rd] = (i32)(m_regs[i.rs1] - m_regs[i.rs2]);
}; break;
case Op::SW: {
u64 addr = m_regs[i.rs1] + i.imm;
*(u32 *)(&m_memory[addr]) = m_regs[i.rs2];
}; break;
case Op::XOR: {
m_regs[i.rd] = m_regs[i.rs1] ^ m_regs[i.rs2];
}; break;
case Op::XORI: {
m_regs[i.rd] = m_regs[i.rs1] ^ i.imm;
}; break;
}
m_pc += 4;
}
}
private:
std::vector<u8> m_memory = std::vector<u8>(MEMORY_SIZE, 0);
std::vector<Ins> m_decoded;
u64 m_pc;
std::array<i64, 32> m_regs{};
Section m_code_section;
static Section get_code_section(Elf *elf, GElf_Ehdr ehdr) {
u64 str_table_index;
if (elf_getshdrstrndx(elf, &str_table_index) != 0) {
std::println(stderr, "elf_getshdrstrndx failed: {}", elf_errmsg(-1));
exit(1);
}
Elf_Scn *section = nullptr;
while ((section = elf_nextscn(elf, section)) != nullptr) {
GElf_Shdr header;
if (gelf_getshdr(section, &header) != &header)
continue;
const char *name = elf_strptr(elf, str_table_index, header.sh_name);
if (name && std::string_view(name) == ".text") {
return Section{.offset = header.sh_addr,
.size = header.sh_size,
.entrypoint = ehdr.e_entry};
}
}
std::println(stderr, "Failed to locate .text");
exit(1);
}
Ins decode_raw(u32 raw) {
u8 opcode = raw & 0b1111111;
Ins i;
i.op = Op::INVALID;
switch (opcode) {
case 0b1100011: {
i.funct3 = (raw >> 12) & 0b111;
i.rs1 = (raw >> 15) & 0b11111;
i.rs2 = (raw >> 20) & 0b11111;
i32 imm_12 = (raw >> 31) & 0b1;
i32 imm_10_5 = (raw >> 25) & 0b111111;
i32 imm_4_1 = (raw >> 8) & 0b1111;
i32 imm_11 = (raw >> 7) & 0b1;
i.imm =
(imm_12 << 12) | (imm_11 << 11) | (imm_10_5 << 5) | (imm_4_1 << 1);
i.imm = (i.imm << 19) >> 19;
if (i.funct3 == 0b000) {
i.op = Op::BEQ;
} else if (i.funct3 == 0b001) {
i.op = Op::BNE;
} else if (i.funct3 == 0b100) {
i.op = Op::BLT;
} else if (i.funct3 == 0b101) {
i.op = Op::BGE;
} else if (i.funct3 == 0b110) {
i.op = Op::BLTU;
} else if (i.funct3 == 0b111) {
i.op = Op::BGEU;
} else {
std::println(stderr, "B-type: unrecognized funct3: {:03b}", i.funct3);
exit(1);
}
}; break;
case 0b0010011: {
i.rd = (raw >> 7) & 0b11111;
i.funct3 = (raw >> 12) & 0b111;
i.rs1 = (raw >> 15) & 0b11111;
i.imm = ((i32)raw) >> 20;
i.shamt = (raw >> 20) & 0b111111;
i.funct6 = (raw >> 26) & 0b111111;
if (i.funct3 == 0b000) {
i.op = Op::ADDI;
} else if (i.funct3 == 0b001) {
if (i.funct6 == 0b000000) {
i.op = Op::SLLI;
} else {
std::println(stderr,
"I-type 1: funct3=001: unrecognized funct6: {:b}",
i.funct6);
exit(1);
}
} else if (i.funct3 == 0b010) {
i.op = Op::SLTI;
} else if (i.funct3 == 0b011) {
i.op = Op::SLTIU;
} else if (i.funct3 == 0b100) {
i.op = Op::XORI;
} else if (i.funct3 == 0b101) {
i.shamt = (raw >> 20) & 0b111111;
i.funct6 = (raw >> 26) & 0b111111;
if (i.funct6 == 0b000000) {
i.op = Op::SRLI;
} else if (i.funct6 == 0b010000) {
i.op = Op::SRAI;
} else {
std::println(stderr,
"I-type 1: funct3=101: unrecognized funct6: {:b}",
i.funct6);
exit(1);
}
} else if (i.funct3 == 0b110) {
i.op = Op::ORI;
} else if (i.funct3 == 0b111) {
i.op = Op::ANDI;
} else {
std::println(stderr, "I-type 1: unrecognized funct3: {:03b}", i.funct3);
exit(1);
}
}; break;
case 0b0000011: {
i.rd = (raw >> 7) & 0b11111;
i.funct3 = (raw >> 12) & 0b111;
i.rs1 = (raw >> 15) & 0b11111;
i.imm = ((i32)raw) >> 20;
if (i.funct3 == 0b000) {
i.op = Op::LB;
} else if (i.funct3 == 0b001) {
i.op = Op::LH;
} else if (i.funct3 == 0b010) {
i.op = Op::LW;
} else if (i.funct3 == 0b011) {
i.op = Op::LD;
} else if (i.funct3 == 0b100) {
i.op = Op::LBU;
} else if (i.funct3 == 0b101) {
i.op = Op::LHU;
} else if (i.funct3 == 0b110) {
i.op = Op::LWU;
} else {
std::println(stderr, "I-type 2: unrecognized funct3: {:03b}", i.funct3);
exit(1);
}
}; break;
case 0b1100111: {
i.rd = (raw >> 7) & 0b11111;
i.funct3 = (raw >> 12) & 0b111;
i.rs1 = (raw >> 15) & 0b11111;
i.imm = ((i32)raw) >> 20;
i.op = Op::JALR;
}; break;
case 0b1110011: {
i.rd = (raw >> 7) & 0b11111;
i.funct3 = (raw >> 12) & 0b111;
i.rs1 = (raw >> 15) & 0b11111;
i.imm = ((i32)raw) >> 20;
if (i.funct3 == 0b000) {
if (i.imm == 0) {
i.op = Op::ECALL;
} else {
std::println(stderr, "I-type 4: funct3=000 unrecognized imm: {:b}",
i.imm);
exit(1);
}
} else {
std::println(stderr, "I-type 4: unrecognized funct3: {:03b}", i.funct3);
exit(1);
}
}; break;
case 0b1101111: {
i.rd = (raw >> 7) & 0b11111;
i32 imm_20 = (raw >> 31) & 0b1;
i32 imm_10_1 = (raw >> 21) & 0b1111111111;
i32 imm_11 = (raw >> 20) & 0b1;
i32 imm_19_12 = (raw >> 12) & 0b11111111;
i.imm =
(imm_20 << 20) | (imm_19_12 << 12) | (imm_11 << 11) | (imm_10_1 << 1);
i.imm = (i.imm << 11) >> 11;
i.op = Op::JAL;
}; break;
case 0b0110011: {
i.rd = (raw >> 7) & 0b11111;
i.funct3 = (raw >> 12) & 0b111;
i.rs1 = (raw >> 15) & 0b11111;
i.rs2 = (raw >> 20) & 0b11111;
i.funct7 = (u8)((raw >> 25) & 0b1111111);
if (i.funct3 == 0b000) {
if (i.funct7 == 0b0000000) {
i.op = Op::ADD;
} else if (i.funct7 == 0b0100000) {
i.op = Op::SUB;
} else if (i.funct7 == 0b0000001) {
i.op = Op::MUL;
} else {
std::println(stderr,
"R-type 1: funct3=0b000: unrecognized funct7: {:b}",
i.funct7);
exit(1);
}
} else if (i.funct3 == 0b001) {
if (i.funct7 == 0b0000000) {
i.op = Op::SLL;
} else if (i.funct7 == 0b0000001) {
i.op = Op::MULH;
} else {
std::println(stderr,
"R-type 1: funct3=0b001: unrecognized funct7: {:b}",
i.funct7);
exit(1);
}
} else if (i.funct3 == 0b010) {
if (i.funct7 == 0b0000000) {
i.op = Op::SLT;
} else {
std::println(stderr,
"R-type 1: funct3=0b010: unrecognized funct7: {:b}",
i.funct7);
exit(1);
}
} else if (i.funct3 == 0b011) {
if (i.funct7 == 0b0000000) {
i.op = Op::SLTU;
} else if (i.funct7 == 0b0000001) {
i.op = Op::MULHU;
} else {
std::println(stderr,
"R-type 1: funct3=0b011: unrecognized funct7: {:b}",
i.funct7);
exit(1);
}
} else if (i.funct3 == 0b100) {
if (i.funct7 == 0b0000000) {
i.op = Op::XOR;
} else if (i.funct7 == 0b0000001) {
i.op = Op::DIV;
} else {
std::println(stderr,
"R-type 1: funct3=0b100: unrecognized funct7: {:b}",
i.funct7);
exit(1);
}
} else if (i.funct3 == 0b101) {
if (i.funct7 == 0b0000000) {
i.op = Op::SRL;
} else if (i.funct7 == 0b0000001) {
i.op = Op::DIVU;
} else if (i.funct7 == 0b0100000) {
i.op = Op::SRA;
} else {
std::println(stderr,
"R-type 1: funct3=0b101: unrecognized funct7: {:b}",
i.funct7);
exit(1);
}
} else if (i.funct3 == 0b110) {
if (i.funct7 == 0b0000001) {
i.op = Op::REM;
} else if (i.funct7 == 0b0000000) {
i.op = Op::OR;
} else {
std::println(stderr,
"R-type 1: funct3=0b110: unrecognized funct7: {:b}",
i.funct7);
exit(1);
}
} else if (i.funct3 == 0b111) {
if (i.funct7 == 0b000) {
i.op = Op::AND;
} else if (i.funct7 == 0b001) {
i.op = Op::REMU;
} else {
std::println(stderr,
"R-type 1: funct3=0b111: unrecognized funct7: {:b}",
i.funct7);
exit(1);
}
} else {
std::println(stderr, "R-type 1: unrecognized funct3: {:03b}", i.funct3);
exit(1);
}
}; break;
case 0b0101111:
std::println(stderr, "A extension not implemented yet.");
exit(1);
case 0b0111011: {
i.rd = (raw >> 7) & 0b11111;
i.funct3 = (raw >> 12) & 0b111;
i.rs1 = (raw >> 15) & 0b11111;
i.rs2 = (raw >> 20) & 0b11111;
i.funct7 = (u8)((raw >> 25) & 0b1111111);
if (i.funct3 == 0b000) {
if (i.funct7 == 0b0000000) {
i.op = Op::ADDW;
} else if (i.funct7 == 0b0100000) {
i.op = Op::SUBW;
} else if (i.funct7 == 0b0000001) {
i.op = Op::MULW;
} else {
std::println(stderr,
"R-type 3: funct3=000: unrecognized funct7: {:b}",
i.funct7);
exit(1);
}
} else if (i.funct3 == 0b001) {
i.op = Op::SLLW;
} else if (i.funct3 == 0b100) {
i.op = Op::DIVW;
} else if (i.funct3 == 0b101) {
if (i.funct7 == 0b0000000) {
i.op = Op::SRLW;
} else if (i.funct7 == 0b0100000) {
i.op = Op::SRAW;
} else if (i.funct7 == 0b0000001) {
i.op = Op::DIVUW;
} else {
std::println(stderr,
"R-type 3: funct3=101: unrecognized funct7: {:b}",
i.funct7);
exit(1);
}
} else if (i.funct3 == 0b110) {
i.op = Op::REMW;
} else if (i.funct3 == 0b111) {
i.op = Op::REMUW;
} else {
std::println(stderr, "R-type 3: unrecognized funct3: {:03b}", i.funct3);
exit(1);
}
}; break;
case 0b0011011: {
i.rd = (raw >> 7) & 0b11111;
i.funct3 = (raw >> 12) & 0b111;
i.rs1 = (raw >> 15) & 0b11111;
i.imm = ((i32)raw) >> 20;
i.shamt = (raw >> 20) & 0b11111;
i.funct7 = (raw >> 25) & 0b1111111;
if (i.funct3 == 0b000) {
i.op = Op::ADDIW;
} else if (i.funct3 == 0b001) {
i.op = Op::SLLIW;
} else if (i.funct3 == 0b101) {
if (i.funct7 == 0b0000000) {
i.op = Op::SRLIW;
} else if (i.funct7 == 0b0100000) {
i.op = Op::SRAIW;
} else {
std::println(stderr,
"R-type 4: funct3=101: unrecognized funct7: {:b}",
i.funct7);
exit(1);
}
} else {
std::println(stderr, "R-type 4: unrecognized funct3: {:03b}", i.funct3);
exit(1);
}
}; break;
case 0b0000111: {
std::println(stderr, "F extension not implemented yet.");
exit(1);
}; break;
case 0b0100111: {
std::println(stderr, "F extension not implemented yet.");
exit(1);
}; break;
case 0b0100011: {
i.funct3 = (raw >> 12) & 0b111;
i.rs1 = (raw >> 15) & 0b11111;
i.rs2 = (raw >> 20) & 0b11111;
i32 imm_11_5 = (raw >> 25) & 0b1111111;
i32 imm_4_0 = (raw >> 7) & 0b11111;
i.imm = (imm_11_5 << 5) | imm_4_0;
i.imm = (i.imm << 20) >> 20;
if (i.funct3 == 0b000) {
i.op = Op::SB;
} else if (i.funct3 == 0b001) {
i.op = Op::SH;
} else if (i.funct3 == 0b010) {
i.op = Op::SW;
} else if (i.funct3 == 0b011) {
i.op = Op::SD;
} else {
std::println(stderr, "S-type: unrecognized funct3: {:03b}", i.funct3);
exit(1);
}
}; break;
case 0b0110111: {
i.rd = (raw >> 7) & 0b11111;
i.imm = raw >> 12;
i.op = Op::LUI;
}; break;
case 0b0010111: {
i.rd = (raw >> 7) & 0b11111;
i.imm = raw >> 12;
i.op = Op::AUIPC;
}; break;
default:
std::println(stderr, "Unrecognized opcode: {:07b}", opcode);
exit(1);
}
return i;
}
};
int main(int argc, char *argv[]) {
if (elf_version(EV_CURRENT) == EV_NONE) {
std::println(stderr, "Failed to initialize libelf: {}", elf_errmsg(-1));
return 1;
}
const char *path = nullptr;
for (int i = 1; i < argc; i++) {
path = argv[i];
}
if (path == nullptr) {
std::println(stderr, "Usage: {} <path>", argv[0]);
return 1;
}
std::ifstream file(path, std::ios::binary | std::ios::ate);
if (!file) {
std::println(stderr, "Failed to open: {}", path);
return 1;
}
i64 exe_size = file.tellg();
file.seekg(0, std::ios::beg);
std::vector<char> exe_bytes(exe_size);
file.read(exe_bytes.data(), exe_size);
file.close();
RISCV64 r(exe_bytes);
exe_bytes.clear();
exe_bytes.shrink_to_fit();
r.disassemble_all();
std::println("END DISASSEMBLY");
r.execute();
}
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