mirror of
https://github.com/TomHarte/CLK.git
synced 2024-11-22 12:33:29 +00:00
117 lines
3.7 KiB
C++
117 lines
3.7 KiB
C++
//
|
|
// Decoder.hpp
|
|
// Clock Signal
|
|
//
|
|
// Created by Thomas Harte on 10/04/2022.
|
|
// Copyright © 2022 Thomas Harte. All rights reserved.
|
|
//
|
|
|
|
#pragma once
|
|
|
|
#include "Instruction.hpp"
|
|
#include "Model.hpp"
|
|
#include "../../Numeric/Sizes.hpp"
|
|
|
|
namespace InstructionSet::M68k {
|
|
|
|
/*!
|
|
A stateless decoder that can map from instruction words to preinstructions
|
|
(i.e. enough to know the operation and size, and either know the addressing mode
|
|
and registers or else know how many further extension words are needed).
|
|
|
|
WARNING: at present this handles the original 68000 instruction set only. It
|
|
requires a model only for the sake of not baking in assumptions about MOVE SR, etc,
|
|
and supporting extended addressing modes in some cases.
|
|
|
|
But it does not yet decode any operations which were not present on the 68000.
|
|
*/
|
|
template <Model model> class Predecoder {
|
|
public:
|
|
Preinstruction decode(uint16_t instruction);
|
|
|
|
private:
|
|
// Page by page decoders; each gets a bit ad hoc so
|
|
// it is neater to separate them.
|
|
Preinstruction decode0(uint16_t instruction);
|
|
Preinstruction decode1(uint16_t instruction);
|
|
Preinstruction decode2(uint16_t instruction);
|
|
Preinstruction decode3(uint16_t instruction);
|
|
Preinstruction decode4(uint16_t instruction);
|
|
Preinstruction decode5(uint16_t instruction);
|
|
Preinstruction decode6(uint16_t instruction);
|
|
Preinstruction decode7(uint16_t instruction);
|
|
Preinstruction decode8(uint16_t instruction);
|
|
Preinstruction decode9(uint16_t instruction);
|
|
Preinstruction decodeA(uint16_t instruction);
|
|
Preinstruction decodeB(uint16_t instruction);
|
|
Preinstruction decodeC(uint16_t instruction);
|
|
Preinstruction decodeD(uint16_t instruction);
|
|
Preinstruction decodeE(uint16_t instruction);
|
|
Preinstruction decodeF(uint16_t instruction);
|
|
|
|
// Yuckiness here: 67 is a count of the number of things contained below in
|
|
// ExtendedOperation; this acts to ensure ExtendedOperation is the minimum
|
|
// integer size large enough to hold all actual operations plus the ephemeral
|
|
// ones used here. Intention is to support table-based decoding, which will mean
|
|
// making those integers less ephemeral, hence the desire to pick a minimum size.
|
|
using OpT = typename MinIntTypeValue<
|
|
uint64_t(OperationMax<model>::value) + 67
|
|
>::type;
|
|
static constexpr auto OpMax = OpT(OperationMax<model>::value);
|
|
|
|
// Specific instruction decoders.
|
|
template <OpT operation, bool validate = true> Preinstruction decode(uint16_t instruction);
|
|
template <OpT operation, bool validate> Preinstruction validated(
|
|
AddressingMode op1_mode = AddressingMode::None, int op1_reg = 0,
|
|
AddressingMode op2_mode = AddressingMode::None, int op2_reg = 0,
|
|
Condition condition = Condition::True,
|
|
int further_extension_words = 0
|
|
);
|
|
template <OpT operation> uint32_t invalid_operands();
|
|
|
|
// Extended operation list; collapses into a single byte enough information to
|
|
// know both the type of operation and how to decode the operands. Most of the
|
|
// time that's knowable from the Operation alone, hence the rather awkward
|
|
// extension of @c Operation.
|
|
enum ExtendedOperation: OpT {
|
|
MOVEPtoRl = OpMax + 1, MOVEPtoRw,
|
|
MOVEPtoMl, MOVEPtoMw,
|
|
|
|
MOVEQ,
|
|
|
|
ADDQb, ADDQw, ADDQl,
|
|
ADDQAw, ADDQAl,
|
|
SUBQb, SUBQw, SUBQl,
|
|
SUBQAw, SUBQAl,
|
|
|
|
ADDIb, ADDIw, ADDIl,
|
|
ORIb, ORIw, ORIl,
|
|
SUBIb, SUBIw, SUBIl,
|
|
ANDIb, ANDIw, ANDIl,
|
|
EORIb, EORIw, EORIl,
|
|
CMPIb, CMPIw, CMPIl,
|
|
|
|
BTSTI, BCHGI, BCLRI, BSETI,
|
|
|
|
CMPMb, CMPMw, CMPMl,
|
|
|
|
ADDtoMb, ADDtoMw, ADDtoMl,
|
|
ADDtoRb, ADDtoRw, ADDtoRl,
|
|
|
|
SUBtoMb, SUBtoMw, SUBtoMl,
|
|
SUBtoRb, SUBtoRw, SUBtoRl,
|
|
|
|
ANDtoMb, ANDtoMw, ANDtoMl,
|
|
ANDtoRb, ANDtoRw, ANDtoRl,
|
|
|
|
ORtoMb, ORtoMw, ORtoMl,
|
|
ORtoRb, ORtoRw, ORtoRl,
|
|
|
|
EXGRtoR, EXGAtoA, EXGRtoA,
|
|
};
|
|
|
|
static constexpr Operation operation(OpT op);
|
|
};
|
|
|
|
}
|