mirror of
https://github.com/TomHarte/CLK.git
synced 2024-11-22 12:33:29 +00:00
231 lines
6.8 KiB
C++
231 lines
6.8 KiB
C++
//
|
|
// Flags.hpp
|
|
// Clock Signal
|
|
//
|
|
// Created by Thomas Harte on 05/10/2023.
|
|
// Copyright © 2023 Thomas Harte. All rights reserved.
|
|
//
|
|
|
|
#pragma once
|
|
|
|
#include "../../Numeric/Carry.hpp"
|
|
|
|
namespace InstructionSet::x86 {
|
|
|
|
namespace FlagValue {
|
|
|
|
//
|
|
// Standard flags.
|
|
//
|
|
|
|
static constexpr uint32_t Carry = 1 << 0;
|
|
static constexpr uint32_t Parity = 1 << 2;
|
|
static constexpr uint32_t AuxiliaryCarry = 1 << 4;
|
|
static constexpr uint32_t Zero = 1 << 6;
|
|
static constexpr uint32_t Sign = 1 << 7;
|
|
static constexpr uint32_t Trap = 1 << 8;
|
|
static constexpr uint32_t Interrupt = 1 << 9;
|
|
static constexpr uint32_t Direction = 1 << 10;
|
|
static constexpr uint32_t Overflow = 1 << 11;
|
|
|
|
//
|
|
// 80286+ additions.
|
|
//
|
|
|
|
static constexpr uint32_t IOPrivilege = (1 << 12) | (1 << 13);
|
|
static constexpr uint32_t NestedTask = 1 << 14;
|
|
|
|
//
|
|
// 16-bit protected mode flags.
|
|
//
|
|
|
|
static constexpr uint32_t ProtectionEnable = 1 << 16;
|
|
static constexpr uint32_t MonitorProcessorExtension = 1 << 17;
|
|
static constexpr uint32_t ProcessorExtensionExtension = 1 << 18;
|
|
static constexpr uint32_t TaskSwitch = 1 << 19;
|
|
|
|
//
|
|
// 32-bit protected mode flags.
|
|
//
|
|
|
|
static constexpr uint32_t Resume = 1 << 16;
|
|
static constexpr uint32_t VirtualMode = 1 << 17;
|
|
|
|
}
|
|
|
|
enum class Flag {
|
|
Carry,
|
|
AuxiliaryCarry,
|
|
Sign,
|
|
Overflow,
|
|
Trap,
|
|
Interrupt,
|
|
Direction,
|
|
Zero,
|
|
ParityOdd
|
|
};
|
|
|
|
enum class Condition {
|
|
Overflow,
|
|
Below,
|
|
Zero,
|
|
BelowOrEqual,
|
|
Sign,
|
|
ParityOdd,
|
|
Less,
|
|
LessOrEqual
|
|
};
|
|
|
|
class Flags {
|
|
public:
|
|
using FlagT = uint32_t;
|
|
|
|
// Flag getters.
|
|
template <Flag flag_v> bool flag() const {
|
|
switch(flag_v) {
|
|
case Flag::Carry: return carry_;
|
|
case Flag::AuxiliaryCarry: return auxiliary_carry_;
|
|
case Flag::Sign: return sign_;
|
|
case Flag::Overflow: return overflow_;
|
|
case Flag::Trap: return trap_;
|
|
case Flag::Interrupt: return interrupt_;
|
|
case Flag::Direction: return direction_ < 0;
|
|
case Flag::Zero: return !zero_;
|
|
case Flag::ParityOdd: return not_parity_bit();
|
|
}
|
|
}
|
|
|
|
// Condition evaluation.
|
|
template <Condition test> bool condition() const {
|
|
switch(test) {
|
|
case Condition::Overflow: return flag<Flag::Overflow>();
|
|
case Condition::Below: return flag<Flag::Carry>();
|
|
case Condition::Zero: return flag<Flag::Zero>();
|
|
case Condition::BelowOrEqual: return flag<Flag::Zero>() || flag<Flag::Carry>();
|
|
case Condition::Sign: return flag<Flag::Sign>();
|
|
case Condition::ParityOdd: return flag<Flag::ParityOdd>();
|
|
case Condition::Less: return flag<Flag::Sign>() != flag<Flag::Overflow>();
|
|
case Condition::LessOrEqual: return flag<Flag::Zero>() || flag<Flag::Sign>() != flag<Flag::Overflow>();
|
|
}
|
|
}
|
|
|
|
// Convenience setters.
|
|
|
|
/// Sets all of @c flags as a function of @c value:
|
|
/// • Flag::Zero: sets the zero flag if @c value is zero;
|
|
/// • Flag::Sign: sets the sign flag if the top bit of @c value is one;
|
|
/// • Flag::ParityOdd: sets parity based on the low 8 bits of @c value;
|
|
/// • Flag::Carry: sets carry if @c value is non-zero;
|
|
/// • Flag::AuxiliaryCarry: sets auxiliary carry if @c value is non-zero;
|
|
/// • Flag::Overflow: sets overflow if @c value is non-zero;
|
|
/// • Flag::Interrupt: sets interrupt if @c value is non-zero;
|
|
/// • Flag::Trap: sets interrupt if @c value is non-zero;
|
|
/// • Flag::Direction: sets direction if @c value is non-zero.
|
|
template <typename IntT, Flag... flags> void set_from(IntT value) {
|
|
for(const auto flag: {flags...}) {
|
|
switch(flag) {
|
|
default: break;
|
|
case Flag::Zero: zero_ = value; break;
|
|
case Flag::Sign: sign_ = value & Numeric::top_bit<IntT>(); break;
|
|
case Flag::ParityOdd: parity_ = value; break;
|
|
case Flag::Carry: carry_ = value; break;
|
|
case Flag::AuxiliaryCarry: auxiliary_carry_ = value; break;
|
|
case Flag::Overflow: overflow_ = value; break;
|
|
case Flag::Interrupt: interrupt_ = value; break;
|
|
case Flag::Trap: trap_ = value; break;
|
|
case Flag::Direction: direction_ = value ? -1 : 1; break;
|
|
}
|
|
}
|
|
}
|
|
template <Flag... flags> void set_from(FlagT value) {
|
|
set_from<FlagT, flags...>(value);
|
|
}
|
|
|
|
template <typename IntT> IntT carry_bit() const { return carry_ ? 1 : 0; }
|
|
bool not_parity_bit() const {
|
|
// x86 parity always considers the lowest 8-bits only.
|
|
auto result = static_cast<uint8_t>(parity_);
|
|
result ^= result >> 4;
|
|
result ^= result >> 2;
|
|
result ^= result >> 1;
|
|
return result & 1;
|
|
}
|
|
|
|
template <typename IntT> IntT direction() const { return static_cast<IntT>(direction_); }
|
|
|
|
// Complete value get and set.
|
|
void set(uint16_t value) {
|
|
set_from<Flag::Carry>(value & FlagValue::Carry);
|
|
set_from<Flag::AuxiliaryCarry>(value & FlagValue::AuxiliaryCarry);
|
|
set_from<Flag::Overflow>(value & FlagValue::Overflow);
|
|
set_from<Flag::Trap>(value & FlagValue::Trap);
|
|
set_from<Flag::Interrupt>(value & FlagValue::Interrupt);
|
|
set_from<Flag::Direction>(value & FlagValue::Direction);
|
|
|
|
set_from<uint8_t, Flag::Sign>(uint8_t(value));
|
|
|
|
set_from<Flag::Zero>((~value) & FlagValue::Zero);
|
|
set_from<Flag::ParityOdd>((~value) & FlagValue::Parity);
|
|
}
|
|
|
|
uint16_t get() const {
|
|
return
|
|
0xf002 |
|
|
|
|
(flag<Flag::Carry>() ? FlagValue::Carry : 0) |
|
|
(flag<Flag::AuxiliaryCarry>() ? FlagValue::AuxiliaryCarry : 0) |
|
|
(flag<Flag::Sign>() ? FlagValue::Sign : 0) |
|
|
(flag<Flag::Overflow>() ? FlagValue::Overflow : 0) |
|
|
(flag<Flag::Trap>() ? FlagValue::Trap : 0) |
|
|
(flag<Flag::Interrupt>() ? FlagValue::Interrupt : 0) |
|
|
(flag<Flag::Direction>() ? FlagValue::Direction : 0) |
|
|
(flag<Flag::Zero>() ? FlagValue::Zero : 0) |
|
|
|
|
(flag<Flag::ParityOdd>() ? 0 : FlagValue::Parity);
|
|
}
|
|
|
|
std::string to_string() const {
|
|
std::string result;
|
|
|
|
if(flag<Flag::Overflow>()) result += "O"; else result += "-";
|
|
if(flag<Flag::Direction>()) result += "D"; else result += "-";
|
|
if(flag<Flag::Interrupt>()) result += "I"; else result += "-";
|
|
if(flag<Flag::Trap>()) result += "T"; else result += "-";
|
|
if(flag<Flag::Sign>()) result += "S"; else result += "-";
|
|
if(flag<Flag::Zero>()) result += "Z"; else result += "-";
|
|
result += "-";
|
|
if(flag<Flag::AuxiliaryCarry>()) result += "A"; else result += "-";
|
|
result += "-";
|
|
if(!flag<Flag::ParityOdd>()) result += "P"; else result += "-";
|
|
result += "-";
|
|
if(flag<Flag::Carry>()) result += "C"; else result += "-";
|
|
|
|
return result;
|
|
}
|
|
|
|
bool operator ==(const Flags &rhs) const {
|
|
return get() == rhs.get();
|
|
}
|
|
|
|
private:
|
|
// Non-zero => set; zero => unset.
|
|
uint32_t carry_;
|
|
uint32_t auxiliary_carry_;
|
|
uint32_t sign_;
|
|
uint32_t overflow_;
|
|
uint32_t trap_;
|
|
uint32_t interrupt_;
|
|
|
|
// +1 = direction flag not set;
|
|
// -1 = direction flag set.
|
|
int32_t direction_;
|
|
|
|
// Zero => set; non-zero => unset.
|
|
uint32_t zero_;
|
|
|
|
// Odd number of bits => set; even => unset.
|
|
uint32_t parity_;
|
|
};
|
|
|
|
}
|