risc/src/parse_program.cpp at main · lhalf/risc · GitHub

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#include "parse_program.hpp"
#include <sstream>
#include <stdexcept>
#include <algorithm>

std::array<std::optional<Instruction>, std::numeric_limits<uint8_t>::max()> parse_program(const std::string& program_text) {
    std::array<std::optional<Instruction>, std::numeric_limits<uint8_t>::max()> instructions{};
    std::istringstream input(program_text);
    std::string line;
    uint8_t index = 0;

    while (std::getline(input, line)) {
        // strip whitespace
        line.erase(0, line.find_first_not_of(" \t"));
        line.erase(line.find_last_not_of(" \t") + 1);

        // ignore empty lines or commented lines
        if (line.empty() || line[0] == '#') continue;

        if (index >= instructions.size()) {
            throw std::runtime_error("program too large for instruction memory");
        }

        instructions.at(index++) = parse_line(line);
    }

    return instructions;
}

Instruction parse_line(const std::string& line) {
    std::istringstream ss(line);
    std::string opcode;
    ss >> opcode;

    if (opcode == "ADD") {
        std::string register_1, register_2, output_register;
        ss >> register_1 >> register_2 >> output_register;
        return Instruction::add(
            parse_register(clean_token(register_1)),
            parse_register(clean_token(register_2)),
            parse_register(clean_token(output_register))
        );
    }
    else if (opcode == "SUB") {
        std::string register_1, register_2, output_register;
        ss >> register_1 >> register_2 >> output_register;
        return Instruction::sub(
            parse_register(clean_token(register_1)),
            parse_register(clean_token(register_2)),
            parse_register(clean_token(output_register))
        );
    }
    else if (opcode == "CMP") {
        std::string register_1, register_2;
        ss >> register_1 >> register_2;
        return Instruction::compare(
            parse_register(clean_token(register_1)),
            parse_register(clean_token(register_2))
        );
    }
    else if (opcode == "LOAD") {
        std::string address, output_register;
        ss >> address >> output_register;
        return Instruction::load(
            parse_u8(clean_token(address)),
            parse_register(clean_token(output_register))
        );
    }
    else if (opcode == "STORE") {
        std::string input_register, address;
        ss >> input_register >> address;
        return Instruction::store(
            parse_register(clean_token(input_register)),
            parse_u8(clean_token(address))
        );
    }
    else if (opcode == "JMP") {
        std::string address;
        ss >> address;
        return Instruction::jump(parse_u8(clean_token(address)));
    }
    else if (opcode == "JMP_EQ") {
        std::string address;
        ss >> address;
        return Instruction::jump_equal(parse_u8(clean_token(address)));
    }
    else if (opcode == "HALT") {
        return Instruction::halt();
    }
    else if (opcode == "PRINT") {
        std::string address;
        ss >> address;
        return Instruction::print(parse_u8(clean_token(address)));
    }
    else {
        throw std::runtime_error("unknown instruction: " + opcode);
    }
}

Register parse_register(const std::string& token) {
    if (token.empty() || token[0] != 'R') {
        throw std::runtime_error("expected register, got: " + token );
    }

    int register_index = std::stoi(token.substr(1));
    if (register_index < 0 || register_index > 7) {
        throw std::runtime_error("register out of bounds: " + token );
    }

    return static_cast<Register>(register_index);
}

uint8_t parse_u8(const std::string& token) {
    int value = std::stoi(token);
    if (value < 0 || value > static_cast<int>(std::numeric_limits<uint8_t>::max())) {
        throw std::runtime_error("u8 value out of bounds: " + token);
    }
    return static_cast<uint8_t>(value);
}

std::string clean_token(std::string token) {
    token.erase(std::remove(token.begin(), token.end(), ','), token.end());
    return token;
}