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Begin support for signed 'S' operations from AVR

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This commit is contained in:
Jason Turner
2021-05-27 12:05:44 -06:00
parent 8b159faa59
commit 841a80f2dd
2 changed files with 31 additions and 0 deletions
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4
include/6502.hpp
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@@ -19,6 +19,7 @@ struct mos6502 : ASMLine
bmi,
bne,
bpl,
bvs,
cpx,
cpy,
@@ -79,6 +80,7 @@ struct mos6502 : ASMLine
case OpCode::bpl:
case OpCode::bcc:
case OpCode::bcs:
case OpCode::bvs:
return true;
case OpCode::adc:
case OpCode::AND:
@@ -145,6 +147,7 @@ struct mos6502 : ASMLine
case OpCode::bpl:
case OpCode::bcc:
case OpCode::bcs:
case OpCode::bvs:
case OpCode::clc:
case OpCode::dec:
case OpCode::dex:
@@ -251,6 +254,7 @@ struct mos6502 : ASMLine
case OpCode::cpx: return "cpx";
case OpCode::dey: return "dey";
case OpCode::iny: return "iny";
case OpCode::bvs: return "bvs";
case OpCode::unknown: return "";
}

27
src/6502-c++.cpp
View File

@@ -94,6 +94,7 @@ struct AVR : ASMLine
andi,
breq,
brge,
brlo,
brne,
brsh,
@@ -207,6 +208,7 @@ struct AVR : ASMLine
if (o == "nop") { return OpCode::nop; }
if (o == "jmp") { return OpCode::jmp; }
if (o == "tst") { return OpCode::tst; }
if (o=="brge"){ return OpCode::brge; }
}
}
throw std::runtime_error(fmt::format("Unknown opcode: {}", o));
@@ -270,6 +272,24 @@ void indirect_store(std::vector<mos6502> &instructions,
instructions.emplace_back(mos6502::OpCode::sta, Operand(Operand::Type::literal, "(" + to_address_low_byte + "), Y"));
}
// returns the "s_set","s_clear" labels to use for later
[[nodiscard]] std::pair<std::string, std::string> setup_S_flag(std::vector<mos6502> &instructions)
{
const auto location = instructions.size();
std::string n_set = fmt::format("n_set_{}", location);
std::string s_set = fmt::format("s_set_{}", location);
std::string s_clear = fmt::format("s_clear_{}", location);
instructions.emplace_back(mos6502::OpCode::bmi, Operand(Operand::Type::literal, n_set));
instructions.emplace_back(mos6502::OpCode::bvs, Operand(Operand::Type::literal, s_set));
instructions.emplace_back(mos6502::OpCode::jmp, Operand(Operand::Type::literal, s_clear));
instructions.emplace_back(ASMLine::Type::Label, n_set);
instructions.emplace_back(mos6502::OpCode::bvs, Operand(Operand::Type::literal, s_clear));
instructions.emplace_back(mos6502::OpCode::jmp, Operand(Operand::Type::literal, s_set));
return {s_set, s_clear};
}
void fixup_16_bit_N_Z_flags(std::vector<mos6502> &instructions)
{
@@ -481,6 +501,13 @@ void translate_instruction(const Personality &personality,
throw std::runtime_error("Unhandled 'std'");
}
case AVR::OpCode::brge: {
const auto [s_set, s_clear] = setup_S_flag(instructions);
instructions.emplace_back(ASMLine::Type::Label, s_clear);
instructions.emplace_back(mos6502::OpCode::jmp, o1);
instructions.emplace_back(ASMLine::Type::Label, s_set);
return;
}
case AVR::OpCode::sub: {
instructions.emplace_back(mos6502::OpCode::sec);
instructions.emplace_back(mos6502::OpCode::lda, personality.get_register(o1_reg_num));