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CLK/InstructionSets/M68k/Instruction.hpp

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11 KiB
C++

//
// Instruction.hpp
// Clock Signal
//
// Created by Thomas Harte on 10/04/2022.
// Copyright © 2022 Thomas Harte. All rights reserved.
//
#ifndef InstructionSets_68k_Instruction_hpp
#define InstructionSets_68k_Instruction_hpp
#include <cstdint>
#include "Model.hpp"
namespace InstructionSet {
namespace M68k {
enum class Operation: uint8_t {
Undefined,
NOP,
ABCD, SBCD, NBCD,
ADDb, ADDw, ADDl,
ADDAw, ADDAl,
ADDXb, ADDXw, ADDXl,
SUBb, SUBw, SUBl,
SUBAw, SUBAl,
SUBXb, SUBXw, SUBXl,
MOVEb, MOVEw, MOVEl,
MOVEAw, MOVEAl,
LEA, PEA,
MOVEtoSR, MOVEfromSR,
MOVEtoCCR,
MOVEtoUSP, MOVEfromUSP,
ORItoSR, ORItoCCR,
ANDItoSR, ANDItoCCR,
EORItoSR, EORItoCCR,
BTST, BCLR,
BCHG, BSET,
CMPb, CMPw, CMPl,
CMPAw, CMPAl,
TSTb, TSTw, TSTl,
JMP,
JSR, RTS,
DBcc,
Scc,
Bccb, Bccw, Bccl,
BSRb, BSRw, BSRl,
CLRb, CLRw, CLRl,
NEGXb, NEGXw, NEGXl,
NEGb, NEGw, NEGl,
ASLb, ASLw, ASLl, ASLm,
ASRb, ASRw, ASRl, ASRm,
LSLb, LSLw, LSLl, LSLm,
LSRb, LSRw, LSRl, LSRm,
ROLb, ROLw, ROLl, ROLm,
RORb, RORw, RORl, RORm,
ROXLb, ROXLw, ROXLl, ROXLm,
ROXRb, ROXRw, ROXRl, ROXRm,
MOVEMl, MOVEMw,
MOVEPl, MOVEPw,
ANDb, ANDw, ANDl,
EORb, EORw, EORl,
NOTb, NOTw, NOTl,
ORb, ORw, ORl,
MULU, MULS,
DIVU, DIVS,
RTE, RTR,
TRAP, TRAPV,
CHK,
EXG, SWAP,
TAS,
EXTbtow, EXTwtol,
LINKw, UNLINK,
STOP, RESET,
Max = RESET
};
template <Model model>
constexpr bool requires_supervisor(Operation op) {
switch(op) {
case Operation::MOVEfromSR:
if constexpr (model == Model::M68000) {
return false;
}
[[fallthrough]];
case Operation::ORItoSR: case Operation::ANDItoSR:
case Operation::EORItoSR: case Operation::RTE:
case Operation::RESET: case Operation::STOP:
case Operation::MOVEtoUSP: case Operation::MOVEfromUSP:
return true;
default:
return false;
}
}
enum class DataSize {
Byte = 0,
Word = 1,
LongWord = 2,
};
/// Classifies operations by the size of their memory accesses, if any.
constexpr DataSize size(Operation operation) {
switch(operation) {
// These are given a value arbitrarily, to
// complete the switch statement.
case Operation::Undefined:
case Operation::NOP:
case Operation::STOP:
case Operation::RESET:
case Operation::RTE: case Operation::RTR:
case Operation::TRAP:
case Operation::TRAPV:
case Operation::ABCD: case Operation::SBCD:
case Operation::NBCD:
case Operation::ADDb: case Operation::ADDXb:
case Operation::SUBb: case Operation::SUBXb:
case Operation::MOVEb:
case Operation::ORItoCCR:
case Operation::ANDItoCCR:
case Operation::EORItoCCR:
case Operation::BTST: case Operation::BCLR:
case Operation::BCHG: case Operation::BSET:
case Operation::CMPb: case Operation::TSTb:
case Operation::Bccb: case Operation::BSRb:
case Operation::CLRb:
case Operation::NEGXb: case Operation::NEGb:
case Operation::ASLb: case Operation::ASRb:
case Operation::LSLb: case Operation::LSRb:
case Operation::ROLb: case Operation::RORb:
case Operation::ROXLb: case Operation::ROXRb:
case Operation::ANDb: case Operation::EORb:
case Operation::NOTb: case Operation::ORb:
case Operation::CHK:
case Operation::TAS:
return DataSize::Byte;
case Operation::ADDw: case Operation::ADDAw:
case Operation::ADDXw: case Operation::SUBw:
case Operation::SUBAw: case Operation::SUBXw:
case Operation::MOVEw: case Operation::MOVEAw:
case Operation::ORItoSR:
case Operation::ANDItoSR:
case Operation::EORItoSR:
case Operation::MOVEtoSR:
case Operation::MOVEfromSR:
case Operation::MOVEtoCCR:
case Operation::CMPw: case Operation::CMPAw:
case Operation::TSTw:
case Operation::DBcc: case Operation::Scc:
case Operation::Bccw: case Operation::BSRw:
case Operation::CLRw:
case Operation::NEGXw: case Operation::NEGw:
case Operation::ASLw: case Operation::ASLm:
case Operation::ASRw: case Operation::ASRm:
case Operation::LSLw: case Operation::LSLm:
case Operation::LSRw: case Operation::LSRm:
case Operation::ROLw: case Operation::ROLm:
case Operation::RORw: case Operation::RORm:
case Operation::ROXLw: case Operation::ROXLm:
case Operation::ROXRw: case Operation::ROXRm:
case Operation::MOVEMw:
case Operation::MOVEPw:
case Operation::ANDw: case Operation::EORw:
case Operation::NOTw: case Operation::ORw:
case Operation::DIVU: case Operation::DIVS:
case Operation::MULU: case Operation::MULS:
case Operation::EXTbtow:
case Operation::LINKw:
return DataSize::Word;
case Operation::ADDl: case Operation::ADDAl:
case Operation::ADDXl: case Operation::SUBl:
case Operation::SUBAl: case Operation::SUBXl:
case Operation::MOVEl: case Operation::MOVEAl:
case Operation::LEA: case Operation::PEA:
case Operation::EXG: case Operation::SWAP:
case Operation::MOVEtoUSP:
case Operation::MOVEfromUSP:
case Operation::CMPl: case Operation::CMPAl:
case Operation::TSTl:
case Operation::JMP: case Operation::JSR:
case Operation::RTS:
case Operation::Bccl: case Operation::BSRl:
case Operation::CLRl:
case Operation::NEGXl: case Operation::NEGl:
case Operation::ASLl: case Operation::ASRl:
case Operation::LSLl: case Operation::LSRl:
case Operation::ROLl: case Operation::RORl:
case Operation::ROXLl: case Operation::ROXRl:
case Operation::MOVEMl:
case Operation::MOVEPl:
case Operation::ANDl: case Operation::EORl:
case Operation::NOTl: case Operation::ORl:
case Operation::EXTwtol:
case Operation::UNLINK:
return DataSize::LongWord;
}
}
template <Operation op>
constexpr uint32_t quick(uint16_t instruction) {
switch(op) {
case Operation::Bccb:
case Operation::BSRb:
case Operation::MOVEl: return uint32_t(int8_t(instruction));
case Operation::TRAP: return uint32_t(instruction & 15);
default: {
uint32_t value = (instruction >> 9) & 7;
value |= (value - 1)&8;
return value;
}
}
}
constexpr uint32_t quick(Operation op, uint16_t instruction) {
switch(op) {
case Operation::MOVEl: return quick<Operation::MOVEl>(instruction);
case Operation::Bccb: return quick<Operation::Bccb>(instruction);
case Operation::BSRb: return quick<Operation::BSRb>(instruction);
case Operation::TRAP: return quick<Operation::TRAP>(instruction);
default:
// ADDw is arbitrary; anything other than those listed above will do.
return quick<Operation::ADDw>(instruction);
}
}
enum class Condition {
True = 0x00, False = 0x01,
High = 0x02, LowOrSame = 0x03,
CarryClear = 0x04, CarrySet = 0x05,
NotEqual = 0x06, Equal = 0x07,
OverflowClear = 0x08, OverflowSet = 0x09,
Positive = 0x0a, Negative = 0x0b,
GreaterThanOrEqual = 0x0c, LessThan = 0x0d,
GreaterThan = 0x0e, LessThanOrEqual = 0x0f,
};
/// Indicates the addressing mode applicable to an operand.
///
/// Implementation notes:
///
/// Those entries starting 0b00 or 0b01 are mapped as per the 68000's native encoding;
/// those starting 0b00 are those which are indicated directly by a mode field and those starting
/// 0b01 are those which are indicated by a register field given a mode of 0b111. The only minor
/// exception is AddressRegisterDirect, which exists on a 68000 but isn't specifiable by a
/// mode and register, it's contextual based on the instruction.
///
/// Those modes starting in 0b10 are the various extended addressing modes introduced as
/// of the 68020, which can be detected only after interpreting an extension word. At the
/// Preinstruction stage:
///
/// * AddressRegisterIndirectWithIndexBaseDisplacement, MemoryIndirectPostindexed
/// and MemoryIndirectPreindexed will have been partially decoded as
/// AddressRegisterIndirectWithIndex8bitDisplacement; and
/// * ProgramCounterIndirectWithIndexBaseDisplacement,
/// ProgramCounterMemoryIndirectPostindexed and
/// ProgramCounterMemoryIndirectPreindexed will have been partially decoded
/// as ProgramCounterIndirectWithIndex8bitDisplacement.
enum class AddressingMode: uint8_t {
/// No adddressing mode; this operand doesn't exist.
None = 0b01'101,
/// Dn
DataRegisterDirect = 0b00'000,
/// An
AddressRegisterDirect = 0b00'001,
/// (An)
AddressRegisterIndirect = 0b00'010,
/// (An)+
AddressRegisterIndirectWithPostincrement = 0b00'011,
/// -(An)
AddressRegisterIndirectWithPredecrement = 0b00'100,
/// (d16, An)
AddressRegisterIndirectWithDisplacement = 0b00'101,
/// (d8, An, Xn)
AddressRegisterIndirectWithIndex8bitDisplacement = 0b00'110,
/// (bd, An, Xn) [68020+]
AddressRegisterIndirectWithIndexBaseDisplacement = 0b10'000,
/// ([bd, An, Xn], od) [68020+]
MemoryIndirectPostindexed = 0b10'001,
/// ([bd, An], Xn, od) [68020+]
MemoryIndirectPreindexed = 0b10'010,
/// (d16, PC)
ProgramCounterIndirectWithDisplacement = 0b01'010,
/// (d8, PC, Xn)
ProgramCounterIndirectWithIndex8bitDisplacement = 0b01'011,
/// (bd, PC, Xn) [68020+]
ProgramCounterIndirectWithIndexBaseDisplacement = 0b10'011,
/// ([bd, PC, Xn], od) [68020+]
ProgramCounterMemoryIndirectPostindexed = 0b10'100,
/// ([bc, PC], Xn, od) [68020+]
ProgramCounterMemoryIndirectPreindexed = 0b10'101,
/// (xxx).W
AbsoluteShort = 0b01'000,
/// (xxx).L
AbsoluteLong = 0b01'001,
/// #
ImmediateData = 0b01'100,
/// .q; value is embedded in the opcode.
Quick = 0b01'110,
};
/*!
A preinstruction is as much of an instruction as can be decoded with
only the first instruction word — i.e. an operation, and:
* on the 68000 and 68010, the complete addressing modes;
* on subsequent, a decent proportion of the addressing mode. See
the notes on @c AddressingMode for potential aliasing.
*/
class Preinstruction {
public:
Operation operation = Operation::Undefined;
// Instructions come with 0, 1 or 2 operands;
// the getters below act to provide a list of operands
// that is terminated by an AddressingMode::None.
//
// For two-operand instructions, argument 0 is a source
// and argument 1 is a destination.
//
// For one-operand instructions, only argument 0 will
// be provided, and will be a source and/or destination as
// per the semantics of the operation.
//
// The versions templated on index do a range check;
// if using the runtime versions then results for indices
// other than 0 and 1 are undefined.
AddressingMode mode(int index) const {
return AddressingMode(operands_[index] & 0x1f);
}
template <int index> AddressingMode mode() const {
if constexpr (index > 1) {
return AddressingMode::None;
}
return mode(index);
}
int reg(int index) const {
return operands_[index] >> 5;
}
template <int index> int reg() const {
if constexpr (index > 1) {
return 0;
}
return reg(index);
}
bool requires_supervisor() const {
return flags_ & 0x80;
}
DataSize size() const {
return DataSize(flags_ & 0x03);
}
Condition condition() const {
return Condition((flags_ >> 2) & 0x0f);
}
private:
uint8_t operands_[2] = { uint8_t(AddressingMode::None), uint8_t(AddressingMode::None)};
uint8_t flags_ = 0;
public:
Preinstruction(
Operation operation,
AddressingMode op1_mode, int op1_reg,
AddressingMode op2_mode, int op2_reg,
bool is_supervisor,
DataSize size,
Condition condition) : operation(operation)
{
operands_[0] = uint8_t(op1_mode) | uint8_t(op1_reg << 5);
operands_[1] = uint8_t(op2_mode) | uint8_t(op2_reg << 5);
flags_ = uint8_t(
(is_supervisor ? 0x80 : 0x00) |
(int(condition) << 2) |
int(size)
);
}
Preinstruction() {}
};
}
}
#endif /* InstructionSets_68k_Instruction_hpp */