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6502-cpp
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6502-cpp/src/6502-c++.cpp

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#include <cassert>
#include <cctype>
#include <ctre.hpp>
#include <fmt/format.h>
#include <fstream>
#include <iostream>
#include <map>
#include <regex>
#include <set>
#include <string>
#include <vector>
#include "../include/assembly.hpp"
#include "../include/6502.hpp"
#include "../include/optimizer.hpp"
#include "../include/personalities/c64.hpp"
int parse_8bit_literal(const std::string &s)
{
return std::stoi(std::string(std::next(std::begin(s)), std::end(s)));
}
std::string_view strip_lo_hi(std::string_view s)
{
const auto matcher = ctre::match<R"((lo|hi)8\((.*)\))">;
if (const auto results = matcher(s); results) {
return results.get<2>();
}
return s;
}
std::string fixup_8bit_literal(const std::string &s)
{
if (s[0] == '$') {
return "#" + std::to_string(static_cast<uint8_t>(parse_8bit_literal(s)));
}
if (s.starts_with("0x")) {
return "#$" + s.substr(2);
}
if (s.starts_with("lo8(")) {
return fmt::format("#<{}", strip_lo_hi(s));
}
if (s.starts_with("hi8(")) {
return fmt::format("#>{}", strip_lo_hi(s));
}
const auto is_num = std::all_of(begin(s), end(s), [](const auto c) { return (c >= '0' && c <= '9') || c == '-'; });
if (is_num) {
return "#<" + s;
}
return s;
}
struct AVR : ASMLine
{
enum class OpCode {
unknown,
adc,
add,
andi,
breq,
brlo,
brne,
brsh,
clr,
com,
cpc,
cpi,
cpse,
dec,
eor,
ld,
ldi,
lds,
lsl,
lsr,
mov,
pop,
push,
rcall,
ret,
rjmp,
rol,
sbci,
sbiw,
sbrc,
sbrs,
st,
sts,
subi,
swap,
};
[[nodiscard]] static constexpr OpCode parse_opcode(Type t, std::string_view o)
{
switch (t) {
case Type::Label:
case Type::Directive:
return OpCode::unknown;
case Type::Instruction: {
if (o == "ldi") { return OpCode::ldi; }
if (o == "sts") { return OpCode::sts; }
if (o == "ret") { return OpCode::ret; }
if (o == "mov") { return OpCode::mov; }
if (o == "lsl") { return OpCode::lsl; }
if (o == "rol") { return OpCode::rol; }
if (o == "rcall") { return OpCode::rcall; }
if (o == "ld") { return OpCode::ld; }
if (o == "subi") { return OpCode::subi; }
if (o == "sbci") { return OpCode::sbci; }
if (o == "st") { return OpCode::st; }
if (o == "lds") { return OpCode::lds; }
if (o == "lsr") { return OpCode::lsr; }
if (o == "andi") { return OpCode::andi; }
if (o == "eor") { return OpCode::eor; }
if (o == "sbrc") { return OpCode::sbrc; }
if (o == "rjmp") { return OpCode::rjmp; }
if (o == "sbrs") { return OpCode::sbrs; }
if (o == "brne") { return OpCode::brne; }
if (o == "dec") { return OpCode::dec; }
if (o == "sbiw") { return OpCode::sbiw; }
if (o == "push") { return OpCode::push; }
if (o == "pop") { return OpCode::pop; }
if (o == "com") { return OpCode::com; }
if (o == "swap") { return OpCode::swap; }
if (o == "clr") { return OpCode::clr; }
if (o == "cpse") { return OpCode::cpse; }
if (o == "cpi") { return OpCode::cpi; }
if (o == "brlo") { return OpCode::brlo; }
if (o == "add") { return OpCode::add; }
if (o == "adc") { return OpCode::adc; }
if (o == "cpc") { return OpCode::cpc; }
if (o == "brsh") { return OpCode::brsh; }
if (o == "breq") { return OpCode::breq; }
}
}
throw std::runtime_error(fmt::format("Unknown opcode: {}"));
}
static int get_register_number(const char reg_name)
{
if (reg_name == 'X') {
return 26;
}
if (reg_name == 'Y') {
return 28;
}
if (reg_name == 'Z') {
return 30;
}
throw std::runtime_error("Unknown register name");
}
static Operand parse_operand(std::string_view o)
{
if (o.empty()) {
return Operand();
}
if (o[0] == 'r' && o.size() > 1) {
return Operand(Operand::Type::reg, atoi(&o[1]));
} else {
return Operand(Operand::Type::literal, std::string{ o });
}
}
AVR(const int t_line_num, std::string_view t_line_text, Type t, std::string_view t_opcode, std::string_view o1 = "", std::string_view o2 = "")
: ASMLine(t, std::string(t_opcode)), line_num(t_line_num), line_text(std::string(t_line_text)),
opcode(parse_opcode(t, t_opcode)), operand1(parse_operand(o1)), operand2(parse_operand(o2))
{
}
int line_num;
std::string line_text;
OpCode opcode;
Operand operand1;
Operand operand2;
};
void indirect_load(std::vector<mos6502> &instructions, const std::string &from_address_low_byte, const std::string &to_address)
{
instructions.emplace_back(mos6502::OpCode::ldy, Operand(Operand::Type::literal, "#0"));
instructions.emplace_back(mos6502::OpCode::lda, Operand(Operand::Type::literal, "(" + from_address_low_byte + "), Y"));
instructions.emplace_back(mos6502::OpCode::sta, Operand(Operand::Type::literal, to_address));
}
void indirect_store(std::vector<mos6502> &instructions, const std::string &from_address, const std::string &to_address_low_byte)
{
instructions.emplace_back(mos6502::OpCode::lda, Operand(Operand::Type::literal, from_address));
instructions.emplace_back(mos6502::OpCode::ldy, Operand(Operand::Type::literal, "#0"));
instructions.emplace_back(mos6502::OpCode::sta, Operand(Operand::Type::literal, "(" + to_address_low_byte + "), Y"));
}
void fixup_16_bit_N_Z_flags(std::vector<mos6502> &instructions)
{
// need to get both Z and N set appropriately
// assuming A contains higher order byte and Y contains lower order byte
instructions.emplace_back(ASMLine::Type::Directive, "; BEGIN remove if next is lda");
instructions.emplace_back(ASMLine::Type::Directive, "; set CPU flags assuming A holds the higher order byte already");
std::string set_flag_label = "flags_set_after_16_bit_op_" + std::to_string(instructions.size());
// if high order is negative, we know it's not 0 and it is negative
instructions.emplace_back(mos6502::OpCode::bmi, Operand(Operand::Type::literal, set_flag_label));
// if it's not 0, then branch down, we know the result is not 0 and not negative
instructions.emplace_back(mos6502::OpCode::bne, Operand(Operand::Type::literal, set_flag_label));
// if the higher order byte is 0, test the lower order byte, which was saved for us in Y
instructions.emplace_back(mos6502::OpCode::txa);
// if low order is not negative, we know it's 0 or not 0
instructions.emplace_back(mos6502::OpCode::bpl, Operand(Operand::Type::literal, set_flag_label));
// if low order byte is negative, shift right by one bit, then we'll get the proper Z/N flags
instructions.emplace_back(mos6502::OpCode::lsr);
instructions.emplace_back(ASMLine::Type::Label, set_flag_label);
instructions.emplace_back(ASMLine::Type::Directive, "; END remove if next is lda");
}
void subtract_16_bit(const Personality &personality, std::vector<mos6502> &instructions, int reg, const std::uint16_t value)
{
//instructions.emplace_back(mos6502::OpCode::sta, Operand(Operand::Type::literal, address_low_byte));
instructions.emplace_back(mos6502::OpCode::sec);
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(reg));
instructions.emplace_back(mos6502::OpCode::sbc, Operand(Operand::Type::literal, "#" + std::to_string((value & 0xFFu))));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(reg));
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(reg + 1));
instructions.emplace_back(mos6502::OpCode::sbc, Operand(Operand::Type::literal, "#" + std::to_string((value >> 8u) & 0xFFu)));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(reg + 1));
instructions.emplace_back(mos6502::OpCode::tax);
fixup_16_bit_N_Z_flags(instructions);
}
void increment_16_bit(const Personality &personality, std::vector<mos6502> &instructions, int reg)
{
//instructions.emplace_back(mos6502::OpCode::sta, Operand(Operand::Type::literal, address_low_byte));
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(reg));
instructions.emplace_back(mos6502::OpCode::clc);
instructions.emplace_back(mos6502::OpCode::adc, Operand(Operand::Type::literal, "#1"));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(reg));
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(reg + 1));
instructions.emplace_back(mos6502::OpCode::adc, Operand(Operand::Type::literal, "#0"));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(reg + 1));
}
void translate_instruction(const Personality &personality, std::vector<mos6502> &instructions, const AVR::OpCode op, const Operand &o1, const Operand &o2)
{
const auto translate_register_number = [](const Operand &reg) {
if (reg.value == "__zero_reg__") {
return 1;
} else if (reg.value == "__temp_reg__") {
return 0;
} else {
return reg.reg_num;
}
};
const auto o1_reg_num = translate_register_number(o1);
const auto o2_reg_num = translate_register_number(o2);
switch (op) {
case AVR::OpCode::dec:
instructions.emplace_back(mos6502::OpCode::dec, personality.get_register(o1_reg_num));
return;
case AVR::OpCode::ldi:
instructions.emplace_back(mos6502::OpCode::lda, Operand(o2.type, fixup_8bit_literal(o2.value)));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
return;
case AVR::OpCode::sts:
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o2_reg_num));
instructions.emplace_back(mos6502::OpCode::sta, Operand(o1.type, o1.value));
return;
case AVR::OpCode::ret:
instructions.emplace_back(mos6502::OpCode::rts);
return;
case AVR::OpCode::mov:
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o2_reg_num));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
return;
case AVR::OpCode::lsl:
instructions.emplace_back(mos6502::OpCode::asl, personality.get_register(o1_reg_num));
return;
case AVR::OpCode::rol:
instructions.emplace_back(mos6502::OpCode::rol, personality.get_register(o1_reg_num));
return;
case AVR::OpCode::rcall:
instructions.emplace_back(mos6502::OpCode::jsr, o1);
return;
case AVR::OpCode::ld: {
if (o2.value == "Z" || o2.value == "X" || o2.value == "Y") {
indirect_load(instructions, personality.get_register(o2.value[0]).value, personality.get_register(o1_reg_num).value);
return;
}
if (o2.value == "Z+" || o2.value == "X+" || o2.value == "Y+") {
indirect_load(instructions, personality.get_register(o2.value[0]).value, personality.get_register(o1_reg_num).value);
increment_16_bit(personality, instructions, AVR::get_register_number(o2.value[0]));
return;
}
throw std::runtime_error("Unhandled ld to non-Z");
}
case AVR::OpCode::sbci: {
// we want to utilize the carry flag, however it was set previously
// (it's really a borrow flag on the 6502)
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));
instructions.emplace_back(mos6502::OpCode::sbc, Operand(o2.type, fixup_8bit_literal(o2.value)));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
fixup_16_bit_N_Z_flags(instructions);
return;
}
case AVR::OpCode::subi: {
// to do: deal with Carry bit (and other flags) nonsense from AVR
// if |x| < |y| -> x-y +carry
// for these special cases with -(1) and -(-(1))
if (o2.value == "lo8(-(-1))") {
instructions.emplace_back(mos6502::OpCode::dec, personality.get_register(o1_reg_num));
return;
}
if (o2.value == "lo8(-(1))") {
instructions.emplace_back(mos6502::OpCode::inc, personality.get_register(o1_reg_num));
return;
}
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));
// have to set carry flag, since it gets inverted by sbc
instructions.emplace_back(mos6502::OpCode::sec);
instructions.emplace_back(mos6502::OpCode::sbc, Operand(o2.type, fixup_8bit_literal(o2.value)));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
// temporarily store lower order (not carried substraction) byte into Y for checking
// later if this is a two byte subtraction operation
instructions.emplace_back(mos6502::OpCode::tax);
return;
}
case AVR::OpCode::st: {
if (o1.value == "Z" || o1.value == "Y" || o1.value == "X") {
indirect_store(instructions, personality.get_register(o2_reg_num).value, personality.get_register(o1.value[0]).value);
return;
}
if (o1.value == "Z+" || o1.value == "Y+" || o1.value == "X+") {
indirect_store(instructions, personality.get_register(o2_reg_num).value, personality.get_register(o1.value[0]).value);
increment_16_bit(personality, instructions, AVR::get_register_number(o1.value[0]));
return;
}
throw std::runtime_error("Unhandled st");
}
case AVR::OpCode::lds: {
instructions.emplace_back(mos6502::OpCode::lda, o2);
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
return;
}
case AVR::OpCode::lsr: {
instructions.emplace_back(mos6502::OpCode::lsr, personality.get_register(o1_reg_num));
return;
}
case AVR::OpCode::andi: {
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));
instructions.emplace_back(mos6502::OpCode::AND, Operand(o2.type, fixup_8bit_literal(o2.value)));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
return;
}
case AVR::OpCode::eor: {
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));
instructions.emplace_back(mos6502::OpCode::eor, personality.get_register(o2_reg_num));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
return;
}
case AVR::OpCode::cpse: {
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));
instructions.emplace_back(mos6502::OpCode::bit, personality.get_register(o2_reg_num));
std::string new_label_name = "skip_next_instruction_" + std::to_string(instructions.size());
instructions.emplace_back(mos6502::OpCode::beq, Operand(Operand::Type::literal, new_label_name));
instructions.emplace_back(ASMLine::Type::Directive, new_label_name);
return;
}
case AVR::OpCode::sbrc: {
instructions.emplace_back(mos6502::OpCode::lda, Operand(o2.type, fixup_8bit_literal("$" + std::to_string(1 << (atoi(o2.value.c_str()))))));
instructions.emplace_back(mos6502::OpCode::bit, personality.get_register(o1_reg_num));
std::string new_label_name = "skip_next_instruction_" + std::to_string(instructions.size());
instructions.emplace_back(mos6502::OpCode::beq, Operand(Operand::Type::literal, new_label_name));
instructions.emplace_back(ASMLine::Type::Directive, new_label_name);
return;
}
case AVR::OpCode::sbrs: {
instructions.emplace_back(mos6502::OpCode::lda, Operand(o2.type, fixup_8bit_literal("$" + std::to_string(1 << (atoi(o2.value.c_str()))))));
instructions.emplace_back(mos6502::OpCode::bit, personality.get_register(o1_reg_num));
std::string new_label_name = "skip_next_instruction_" + std::to_string(instructions.size());
instructions.emplace_back(mos6502::OpCode::bne, Operand(Operand::Type::literal, new_label_name));
instructions.emplace_back(ASMLine::Type::Directive, new_label_name);
return;
}
case AVR::OpCode::brne: {
if (o1.value == "0b") {
instructions.emplace_back(mos6502::OpCode::bne, Operand(Operand::Type::literal, "memcpy_0"));
} else {
instructions.emplace_back(mos6502::OpCode::bne, o1);
}
return;
}
case AVR::OpCode::rjmp: {
instructions.emplace_back(mos6502::OpCode::jmp, o1);
return;
}
case AVR::OpCode::sbiw: {
subtract_16_bit(personality, instructions, o1_reg_num, static_cast<std::uint16_t>(std::stoi(o2.value)));
return;
}
case AVR::OpCode::push: {
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));
instructions.emplace_back(mos6502::OpCode::pha);
return;
}
case AVR::OpCode::pop: {
instructions.emplace_back(mos6502::OpCode::pla);
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
return;
}
case AVR::OpCode::com: {
// We're doing this in the same way the AVR does it, to make sure the C flag is set properly
instructions.emplace_back(mos6502::OpCode::clc);
instructions.emplace_back(mos6502::OpCode::lda, Operand(Operand::Type::literal, "#$FF"));
instructions.emplace_back(mos6502::OpCode::sbc, personality.get_register(o1_reg_num));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
return;
}
case AVR::OpCode::clr: {
instructions.emplace_back(mos6502::OpCode::lda, Operand(Operand::Type::literal, "#$00"));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
return;
}
case AVR::OpCode::cpi: {
// note that this will leave the C flag in the 6502 borrow state, not normal carry state
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));
instructions.emplace_back(mos6502::OpCode::cmp, Operand(o2.type, fixup_8bit_literal(o2.value)));
return;
}
case AVR::OpCode::brlo: {
if (o1.value == ".+2") {
// assumes 6502 'borrow' for Carry flag instead of carry, so bcc instead of bcs
std::string new_label_name = "skip_next_instruction_" + std::to_string(instructions.size());
instructions.emplace_back(mos6502::OpCode::bcc, Operand(Operand::Type::literal, new_label_name));
instructions.emplace_back(ASMLine::Type::Directive, new_label_name);
return;
} else {
instructions.emplace_back(mos6502::OpCode::bcc, o1);
return;
}
}
case AVR::OpCode::swap: {
// from http://www.6502.org/source/general/SWN.html
// ASL A
// ADC #$80
// ROL A
// ASL A
// ADC #$80
// ROL A
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));
instructions.emplace_back(mos6502::OpCode::asl);
instructions.emplace_back(mos6502::OpCode::adc, Operand(Operand::Type::literal, "#$80"));
instructions.emplace_back(mos6502::OpCode::rol);
instructions.emplace_back(mos6502::OpCode::asl);
instructions.emplace_back(mos6502::OpCode::adc, Operand(Operand::Type::literal, "#$80"));
instructions.emplace_back(mos6502::OpCode::rol);
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
return;
}
case AVR::OpCode::add: {
instructions.emplace_back(mos6502::OpCode::clc);
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));
instructions.emplace_back(mos6502::OpCode::adc, personality.get_register(o2_reg_num));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
return;
}
case AVR::OpCode::adc: {
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));
instructions.emplace_back(mos6502::OpCode::adc, personality.get_register(o2_reg_num));
instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(o1_reg_num));
return;
}
case AVR::OpCode::cpc: {
// this instruction seems to need to be used in the case after a sbc operation, where the
// carry flag is set to the appropriate borrow state, so I'm going to not invert
// the carry flag here, and assume that it's set how the 6502 wants it to be
// set from the previous operation
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));
instructions.emplace_back(mos6502::OpCode::sbc, personality.get_register(o2_reg_num));
return;
}
case AVR::OpCode::brsh: {
if (o1.value == ".+2") {
// assumes 6502 'borrow' for Carry flag instead of carry, so bcs instead of bcc
std::string new_label_name = "skip_next_instruction_" + std::to_string(instructions.size());
instructions.emplace_back(mos6502::OpCode::bcs, Operand(Operand::Type::literal, new_label_name));
instructions.emplace_back(ASMLine::Type::Directive, new_label_name);
return;
} else {
instructions.emplace_back(mos6502::OpCode::bcs, o1);
return;
}
}
case AVR::OpCode::breq: {
instructions.emplace_back(mos6502::OpCode::beq, o1);
return;
}
case AVR::OpCode::unknown: {
throw std::runtime_error("Could not translate 'unknown' instruction");
}
}
throw std::runtime_error("Could not translate unhandled instruction");
}
enum class LogLevel {
Warning,
Error
};
std::string to_string(const LogLevel ll)
{
switch (ll) {
case LogLevel::Warning:
return "warning";
case LogLevel::Error:
return "error";
}
return "unknown";
}
void log(LogLevel ll, const AVR &i, const std::string &message)
{
std::cerr << to_string(ll) << ": " << i.line_num << ": " << message << ": `" << i.line_text << "`\n";
}
void log(LogLevel ll, const std::size_t line_no, const std::string &line, const std::string &message)
{
std::cerr << to_string(ll) << ": " << line_no << ": " << message << ": `" << line << "`\n";
}
void to_mos6502(const Personality &personality, const AVR &from_instruction, std::vector<mos6502> &instructions)
{
try {
switch (from_instruction.type) {
case ASMLine::Type::Label:
if (from_instruction.text == "0") {
instructions.emplace_back(from_instruction.type, "-memcpy_0");
} else {
instructions.emplace_back(from_instruction.type, from_instruction.text);
}
return;
case ASMLine::Type::Directive:
if (from_instruction.text.starts_with(".string")) {
instructions.emplace_back(ASMLine::Type::Directive, ".asc " + from_instruction.text.substr(7));
} else if (from_instruction.text.starts_with(".zero")) {
const auto count = std::stoull(&*std::next(from_instruction.text.begin(), 6), nullptr, 10);
std::string zeros;
for (std::size_t i = 0; i < count; ++i) {
if ((i % 40) == 0) {
if (!zeros.empty()) {
instructions.emplace_back(ASMLine::Type::Directive, zeros);
zeros.clear();
}
zeros += ".byt 0";
} else {
zeros += ",0";
}
}
if (!zeros.empty()) {
instructions.emplace_back(ASMLine::Type::Directive, zeros);
}
} else {
instructions.emplace_back(ASMLine::Type::Directive, "; Unknown directive: " + from_instruction.text);
}
return;
case ASMLine::Type::Instruction:
const auto head = instructions.size();
try {
translate_instruction(personality, instructions, from_instruction.opcode, from_instruction.operand1, from_instruction.operand2);
} catch (const std::exception &e) {
instructions.emplace_back(ASMLine::Type::Directive, "; Unhandled opcode: '" + from_instruction.text + "' " + e.what());
log(LogLevel::Error, from_instruction, e.what());
}
auto text = from_instruction.line_text;
if (text[0] == '\t') {
text.erase(0, 1);
}
for_each(std::next(instructions.begin(), static_cast<std::ptrdiff_t>(head)), instructions.end(), [text](auto &ins) {
ins.comment = text;
});
return;
}
} catch (const std::exception &e) {
log(LogLevel::Error, from_instruction, e.what());
}
}
bool fix_long_branches(std::vector<mos6502> &instructions, int &branch_patch_count)
{
std::map<std::string, size_t> labels;
for (size_t op = 0; op < instructions.size(); ++op) {
if (instructions[op].type == ASMLine::Type::Label) {
labels[instructions[op].text] = op;
}
}
for (size_t op = 0; op < instructions.size(); ++op) {
if (instructions[op].is_branch && std::abs(static_cast<int>(labels[instructions[op].op.value]) - static_cast<int>(op)) * 3 > 255) {
++branch_patch_count;
const auto going_to = instructions[op].op.value;
const auto new_pos = "patch_" + std::to_string(branch_patch_count);
// uh-oh too long of a branch, have to convert this to a jump...
std::map<mos6502::OpCode, mos6502::OpCode> branch_mapping;
branch_mapping[mos6502::OpCode::bne] = mos6502::OpCode::beq;
branch_mapping[mos6502::OpCode::beq] = mos6502::OpCode::bne;
branch_mapping[mos6502::OpCode::bcc] = mos6502::OpCode::bcs;
branch_mapping[mos6502::OpCode::bcs] = mos6502::OpCode::bcc;
const auto mapping = branch_mapping.find(instructions[op].opcode);
if (mapping != branch_mapping.end()) {
const auto comment = instructions[op].comment;
instructions[op] = mos6502(mapping->second, Operand(Operand::Type::literal, new_pos));
instructions.insert(std::next(std::begin(instructions), static_cast<std::ptrdiff_t>(op + 1)), mos6502(mos6502::OpCode::jmp, Operand(Operand::Type::literal, going_to)));
instructions.insert(std::next(std::begin(instructions), static_cast<std::ptrdiff_t>(op + 2)), mos6502(ASMLine::Type::Label, new_pos));
instructions[op].comment = instructions[op + 1].comment = instructions[op + 2].comment = comment;
return true;
}
throw std::runtime_error("Don't know how to reorg this branch: " + instructions[op].to_string());
}
}
return false;
}
bool fix_overwritten_flags(std::vector<mos6502> &instructions)
{
if (instructions.size() < 3) {
return false;
}
for (size_t op = 0; op < instructions.size(); ++op) {
if (instructions[op].is_comparison) {
auto op2 = op + 1;
while (op2 < instructions.size()
&& !instructions[op2].is_comparison
&& !instructions[op2].is_branch) {
++op2;
}
if (op2 < instructions.size()
&& (op2 - op) > 1
&& instructions[op2 - 1].opcode != mos6502::OpCode::plp) {
if (instructions[op2].is_comparison) {
continue;
}
if (instructions[op2].is_branch) {
// insert a pull of processor status before the branch
instructions.insert(std::next(std::begin(instructions), static_cast<std::ptrdiff_t>(op2)), mos6502(mos6502::OpCode::plp));
// insert a push of processor status after the comparison
instructions.insert(std::next(std::begin(instructions), static_cast<std::ptrdiff_t>(op + 1)), mos6502(mos6502::OpCode::php));
return true;
}
}
}
}
return false;
}
void run(const Personality &personality, std::istream &input)
{
std::regex Comment(R"(\s*\#.*)");
std::regex Label(R"(^\s*(\S+):.*)");
std::regex Directive(R"(^\s*(\..+))");
std::regex UnaryInstruction(R"(^\s+(\S+)\s+(\S+))");
std::regex BinaryInstruction(R"(^\s+(\S+)\s+(\S+),\s*(\S+))");
std::regex Instruction(R"(^\s+(\S+))");
std::size_t lineno = 0;
std::vector<AVR> instructions;
while (input.good()) {
std::string line;
getline(input, line);
try {
std::smatch match;
if (std::regex_match(line, match, Label)) {
instructions.emplace_back(lineno, line, ASMLine::Type::Label, match[1].str());
} else if (std::regex_match(line, match, Comment)) {
// don't care about comments
} else if (std::regex_match(line, match, Directive)) {
instructions.emplace_back(lineno, line, ASMLine::Type::Directive, match[1].str());
} else if (std::regex_match(line, match, BinaryInstruction)) {
instructions.emplace_back(lineno, line, ASMLine::Type::Instruction, match[1].str(), match[2].str(), match[3].str());
} else if (std::regex_match(line, match, UnaryInstruction)) {
instructions.emplace_back(lineno, line, ASMLine::Type::Instruction, match[1].str(), match[2].str());
} else if (std::regex_match(line, match, Instruction)) {
instructions.emplace_back(lineno, line, ASMLine::Type::Instruction, match[1].str());
} else if (line.empty()) {
// skip empty lines
}
} catch (const std::exception &e) {
log(LogLevel::Error, lineno, line, e.what());
}
++lineno;
}
std::set<std::string> labels;
for (const auto &i : instructions) {
if (i.type == ASMLine::Type::Label) {
labels.insert(i.text);
}
}
std::set<std::string> used_labels{ "main" };
for (const auto &i : instructions) {
if (i.type == ASMLine::Type::Instruction) {
const auto check_label = [&](const std::string &value) {
if (labels.count(value) != 0) {
used_labels.insert(value);
}
};
check_label(i.operand1.value);
check_label(i.operand2.value);
check_label(std::string{ strip_lo_hi(i.operand1.value) });
check_label(std::string{ strip_lo_hi(i.operand2.value) });
}
}
const auto new_labels =
[&used_labels]() {
std::map<std::string, std::string> result;
for (const auto &l : used_labels) {
auto newl = l;
std::transform(newl.begin(), newl.end(), newl.begin(), [](const auto c) { return std::tolower(c); });
newl.erase(std::remove_if(newl.begin(), newl.end(), [](const auto c) { return !std::isalnum(c); }), std::end(newl));
result.emplace(std::make_pair(l, newl));
}
return result;
}();
for (auto &i : instructions) {
if (i.type == ASMLine::Type::Label) {
if (i.text == "0") {
i.text = "-memcpy_0";
} else {
i.text = new_labels.at(i.text);
}
}
if (i.operand2.value.starts_with("lo8(") || i.operand2.value.starts_with("hi8(")) {
const auto potential_label = strip_lo_hi(i.operand2.value);
const auto itr1 = new_labels.find(std::string{ potential_label });
if (itr1 != new_labels.end()) {
i.operand2.value.replace(4, potential_label.size(), itr1->second);
}
}
const auto itr1 = new_labels.find(i.operand1.value);
if (itr1 != new_labels.end()) {
i.operand1.value = itr1->second;
}
const auto itr2 = new_labels.find(i.operand2.value);
if (itr2 != new_labels.end()) {
i.operand2.value = itr2->second;
}
}
std::vector<mos6502> new_instructions;
personality.insert_autostart_sequence(new_instructions);
// set __zero_reg__ (reg 1 on AVR) to 0
new_instructions.emplace_back(mos6502::OpCode::lda, Operand(Operand::Type::literal, "#$00"));
new_instructions.emplace_back(mos6502::OpCode::sta, personality.get_register(1));
new_instructions.emplace_back(mos6502::OpCode::jmp, Operand(Operand::Type::literal, "main"));
int instructions_to_skip = 0;
std::string next_label_name;
for (const auto &i : instructions) {
to_mos6502(personality, i, new_instructions);
// intentionally copy so we don't invalidate the reference
const auto last_instruction = new_instructions.back();
const auto last_instruction_loc = new_instructions.size() - 1;
if (instructions_to_skip == 1) {
new_instructions.emplace_back(ASMLine::Type::Label, next_label_name);
}
--instructions_to_skip;
if (last_instruction.type == ASMLine::Type::Directive && last_instruction.text.starts_with("skip_next_instruction")) {
instructions_to_skip = 1;
next_label_name = last_instruction.text;
new_instructions.erase(std::next(new_instructions.begin(), static_cast<std::ptrdiff_t>(last_instruction_loc)));
}
if (last_instruction.type == ASMLine::Type::Directive && last_instruction.text.starts_with("skip_next_2_instructions")) {
instructions_to_skip = 2;
next_label_name = last_instruction.text;
new_instructions.erase(std::next(new_instructions.begin(), static_cast<std::ptrdiff_t>(last_instruction_loc)));
}
}
while (fix_overwritten_flags(new_instructions)) {
// do it however many times it takes
}
while (optimize(new_instructions)) {
// do it however many times it takes
}
int branch_patch_count = 0;
while (fix_long_branches(new_instructions, branch_patch_count)) {
// do it however many times it takes
}
for (const auto &i : new_instructions) {
std::cout << i.to_string() << '\n';
}
}
int main(const int argc, const char **argv)
{
std::ifstream input_file;
std::istream &input = [&]() -> std::istream & {
if (argc > 1) {
input_file.open(argv[1]);
return input_file;
} else {
return std::cin;
}
}();
C64 personality;
std::cout << "; AVR Mode\n";
run(personality, input);
}
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