package instr

import (
	"git.elyanpoujol.fr/elyan/central-arch/pkg/register"
)

type Instr uint32
type InstrFormat uint32

const (
	A1 InstrFormat = iota
	A2
	B1
	B2
	C
	D1
	D2
	E
)

var instrFormatNames = [...]string{
	"A1",
	"A2",
	"B1",
	"B2",
	"C",
	"D1",
	"D2",
	"E",
}

func (instrf InstrFormat) String() string {
	if int(instrf) > len(instrFormatNames) {
		panic("unknown instruction format")
	}

	return instrFormatNames[instrf]
}

type Cond uint32

const (
	AL  Cond = iota     // Always
	EQ                  // Equal, Z==1
	NEQ                 // Not Equal, Z==0
	UGE                 // Unsigned Greater or Equal, C==1
	CS  Cond = iota - 1 // Carry Set, C==1
	ULT                 // Unsigned Lower Than, C==0
	CC  Cond = iota - 2 // Carry Clear, C==0
	NEG                 // Negative, N==1
	POS                 // Positive, N==0
	VS                  // oVerflow Set, V==1
	VC                  // oVerflow Clear, V==0
	UGT                 // Unsigned Greater Than, C==1 && Z==0
	ULE                 // Unsigned Lower Than, C==0 && Z==1
	SGE                 // Signed Greater or Equal, N==V
	SLT                 // Signed Lower Than, N!=V
	SGT                 // Signed Greater Than, Z==0 && N==V
	SLE                 // Signed Lower or Equal, Z==1 && N!=V
)

var condNames = [...]string{
	"al",
	"eq",
	"neq",
	"uge",
	"cs",
	"ult",
	"cc",
	"neg",
	"pos",
	"vs",
	"vc",
	"ugt",
	"ule",
	"sge",
	"slt",
	"sgt",
	"sle",
}

func (cond Cond) String() string {
	if int(cond) > len(condNames) {
		panic("unknown instruction condition")
	}

	return condNames[cond]
}

type InstrFormatter func(*DecodedInstr) string

type InstrDesc struct {
	VariantName string
	Mnemonic    string
	OpCode      uint32
	Format      InstrFormat
	Formatter   InstrFormatter
}

type StandardFormatFields struct {
	Condition Cond
	Rd        register.CpuRegister
	Rs1       register.CpuRegister
	Rs2       register.CpuRegister
	Imm       uint32
}

type SubsystemFormatFields struct {
	Reg register.CpuRegister
	Sid uint32
	Sre uint32
	Cmd uint32
}

type DecodedInstr struct {
	InstrDesc InstrDesc
	// A, B, C, D1 and D2 formats fields
	StandardFormatFields
	// E format fields
	SubsystemFormatFields
}