svm/assembler.cpp at master · sschellhoff/svm · GitHub

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#include"assembler.hpp"
#include<map>
#include<cctype>
#include"command_info.hpp"
#include<iostream>

enum TokenType {
WHITESPACE,
SOURCE,
TARGET,
COMMAND,
NUMBER
};

structTokenValue {
 std::string str;
 int_type no;
 command_type cmd;
};

structToken {
 TokenType type;
 TokenValue value;

Token() {}
Token(TokenType type) : type(type) {}
};

std::vector<command_type> error_program() {
return {Command::HALT};
}

std::vector<command_type> assemble(const std::string & program) {
 std::map<std::string, std::vector<std::size_t>> unknown_label_positions;
 std::map<std::string, std::size_t> label_positions;

 std::vector<command_type> result;

 std::size_t pos = 0;
 std::vector<Token> tokens;

while(pos < program.length()) {
auto start_pos = pos;
auto current = program[pos];

if(std::isspace(current)) {
for(;pos < program.length() && std::isspace(current); current = program[++pos]) {
 }
 Token ws(TokenType::WHITESPACE);
 tokens.push_back(ws);
continue;
 }

if(std::isalpha(current)) {
for(;pos < program.length() && std::isalpha(current); current = program[++pos]) {
 }
auto value = program.substr(start_pos, pos-start_pos);
if(pos < program.length() && current == ':') {
 pos++;
 Token target(TokenType::TARGET);
 target.value.str = value;
 tokens.push_back(target);
 } else {
if(doesCommandExist(value)) {
 Token cmd(TokenType::COMMAND);
 cmd.value.cmd = translateCommand(value);
 tokens.push_back(cmd);
 } else {
 Token src(TokenType::SOURCE);
 src.value.str = value;
 tokens.push_back(src);
 }
 }
continue;
 }

if(current == '-') {
 pos++;
if(pos >= program.length()) {
 std::cerr << "Unknown token" << std::endl;
returnerror_program();
 }
 current = program[pos];
 }
if(std::isdigit(current)) {
for(;pos < program.length() && std::isdigit(current); current = program[++pos]) {
 }
 int_type value = std::stoi(program.substr(start_pos, pos-start_pos));
 Token no(TokenType::NUMBER);
 no.value.no = value;
 tokens.push_back(no);
continue;
 }

// error
 std::cerr << "Unknown token" << std::endl;
returnerror_program();
 }

 pos = 0;
while(pos < tokens.size()) {
switch(tokens[pos].type) {
case TokenType::WHITESPACE:
break;
case TokenType::TARGET: {
auto target = tokens[pos].value.str;
if(label_positions.find(target) != label_positions.end()) {
 std::cerr << "Target is already defined: " << target << std::endl;
returnerror_program();
 }
if(unknown_label_positions.find(target) != unknown_label_positions.end()) {
for(auto label : unknown_label_positions.find(target)->second) {
 result[label] = result.size();
 }
 unknown_label_positions.erase(unknown_label_positions.find(target));
 }
 label_positions[target] = result.size();
 }
break;
case TokenType::SOURCE: {
auto source = tokens[pos].value.str;
if(label_positions.find(source) != label_positions.end()) {
 result.push_back(label_positions.find(source)->second);
 } else {
 unknown_label_positions[source].push_back(result.size());
 result.push_back(-1);
 }
 }
break;
case TokenType::NUMBER:
 result.push_back(tokens[pos].value.no);
break;
case TokenType::COMMAND:
 result.push_back(tokens[pos].value.cmd);
break;
default: {
 std::cerr << "Unknown tokentype" << std::endl;
returnerror_program();
 }

 }
 pos++;
 }
if(unknown_label_positions.size() > 0) {
 std::cerr << "There are are missing targets" << std::endl;
for(constauto &[key, value] : unknown_label_positions) {
 std::cerr << key << std::endl;
 }
 }

return result;
}