package cpu

// 6502 Addressing modes
const (
	_ = iota
	absolute
	absoluteX
	absoluteY
	accumulator
	immediate
	implied
	indirect
	indirectX
	indirectY
	relative
	zeropage
	zeropageX
	zeropageY
)

// Human readable address modes
var addressingNames = [...]string{
	"",
	"absolute",
	"absoluteX",
	"absoluteY",
	"accumulator",
	"immediate",
	"implied",
	"(indirect)",
	"(indirect,X)",
	"(indirect),Y",
	"relative",
	"zeropage",
	"zeropageX",
	"zeropageY",
}

// 6502 Instruction mnemonics.
// OpCodes are a combination of an instruction and an addressing mode
const (
	_ = iota
	adc
	and
	asl
	bcc
	bcs
	beq
	bit
	bmi
	bne
	bpl
	brk
	bvc
	bvs
	clc
	cld
	cli
	clv
	cmp
	cpx
	cpy
	dec
	dex
	dey
	eor
	inc
	inx
	iny
	jmp
	jsr
	lda
	ldx
	ldy
	lsr
	nop
	ora
	pha
	php
	pla
	plp
	rol
	ror
	rti
	rts
	sbc
	sec
	sed
	sei
	sta
	stx
	sty
	tax
	tay
	tsx
	txa
	txs
	tya
	_end
)

// Human readable instruction mnemonics
var instructionNames = [...]string{
	"",
	"ADC",
	"AND",
	"ASL",
	"BCC",
	"BCS",
	"BEQ",
	"BIT",
	"BMI",
	"BNE",
	"BPL",
	"BRK",
	"BVC",
	"BVS",
	"CLC",
	"CLD",
	"CLI",
	"CLV",
	"CMP",
	"CPX",
	"CPY",
	"DEC",
	"DEX",
	"DEY",
	"EOR",
	"INC",
	"INX",
	"INY",
	"JMP",
	"JSR",
	"LDA",
	"LDX",
	"LDY",
	"LSR",
	"NOP",
	"ORA",
	"PHA",
	"PHP",
	"PLA",
	"PLP",
	"ROL",
	"ROR",
	"RTI",
	"RTS",
	"SBC",
	"SEC",
	"SED",
	"SEI",
	"STA",
	"STX",
	"STY",
	"TAX",
	"TAY",
	"TSX",
	"TXA",
	"TXS",
	"TYA",
	"_END",
}

// The OpType consists of a 6502 instruction and addressing mode.
// It does not include any following operand
type OpType struct {
	// Opcode is the instruction + addresing mode
	Opcode byte

	// Internal id for the used instruction/mnemonic
	id uint8

	// Internal id for the addressing mode
	addressing uint8

	// Bytes is the size of the instruction and its expected operands.
	// 1 byte: opcode with implicit or null operand
	// 2 bytes: opcode with immediate or zeropage operand (8-bit operand)
	// 3 bytes: opcode with address operands
	Bytes uint8

	// Cycles, number of clock cycles it takes to execute this opcode
	Cycles uint8
}

// See http://www.e-tradition.net/bytes/6502/6502_instruction_set.html for details
var optypes = map[uint8]OpType{
	0x69: OpType{0x69, adc, immediate, 2, 2},
	0x65: OpType{0x69, adc, zeropage, 2, 3},
	0x75: OpType{0x75, adc, zeropageX, 2, 4},
	0x6D: OpType{0x6D, adc, absolute, 3, 4},
	0x7D: OpType{0x7D, adc, absoluteX, 3, 4},
	0x79: OpType{0x79, adc, absoluteY, 3, 4},
	0x61: OpType{0x61, adc, indirectX, 2, 6},
	0x71: OpType{0x71, adc, indirectY, 2, 5},
	0x29: OpType{0x29, and, immediate, 2, 2},
	0x25: OpType{0x25, and, zeropage, 2, 3},
	0x35: OpType{0x35, and, zeropageX, 2, 4},
	0x2D: OpType{0x2D, and, absolute, 3, 4},
	0x3D: OpType{0x3D, and, absoluteX, 3, 4},
	0x39: OpType{0x39, and, absoluteY, 3, 4},
	0x21: OpType{0x21, and, indirectX, 2, 6},
	0x31: OpType{0x31, and, indirectY, 2, 5},
	0x0A: OpType{0x0A, asl, accumulator, 1, 2},
	0x06: OpType{0x06, asl, zeropage, 2, 5},
	0x16: OpType{0x16, asl, zeropageX, 2, 6},
	0x0E: OpType{0x0E, asl, absolute, 3, 6},
	0x1E: OpType{0x1E, asl, absoluteX, 3, 7},
	0x90: OpType{0x90, bcc, relative, 2, 2},
	0xB0: OpType{0xB0, bcs, relative, 2, 2},
	0xF0: OpType{0xF0, beq, relative, 2, 2},
	0x24: OpType{0x24, bit, zeropage, 2, 3},
	0x2C: OpType{0x2C, bit, absolute, 3, 4},
	0x30: OpType{0x30, bmi, relative, 2, 2},
	0xD0: OpType{0xD0, bne, relative, 2, 2},
	0x10: OpType{0x10, bpl, relative, 2, 2},
	0x00: OpType{0x00, brk, implied, 1, 7},
	0x50: OpType{0x50, bvc, relative, 2, 2},
	0x70: OpType{0x70, bvs, relative, 2, 2},
	0x18: OpType{0x18, clc, implied, 1, 2},
	0xD8: OpType{0xD8, cld, implied, 1, 2},
	0x58: OpType{0x58, cli, implied, 1, 2},
	0xB8: OpType{0xB8, clv, implied, 1, 2},
	0xC9: OpType{0xC9, cmp, immediate, 2, 2},
	0xC5: OpType{0xC5, cmp, zeropage, 2, 3},
	0xD5: OpType{0xD5, cmp, zeropageX, 2, 4},
	0xCD: OpType{0xCD, cmp, absolute, 3, 4},
	0xDD: OpType{0xDD, cmp, absoluteX, 3, 4},
	0xD9: OpType{0xD9, cmp, absoluteY, 3, 4},
	0xC1: OpType{0xC1, cmp, indirectX, 2, 6},
	0xD1: OpType{0xD1, cmp, indirectY, 2, 5},
	0xE0: OpType{0xE0, cpx, immediate, 2, 2},
	0xE4: OpType{0xE4, cpx, zeropage, 2, 3},
	0xEC: OpType{0xEC, cpx, absolute, 3, 4},
	0xC0: OpType{0xC0, cpy, immediate, 2, 2},
	0xC4: OpType{0xC4, cpy, zeropage, 2, 3},
	0xCC: OpType{0xCC, cpy, absolute, 3, 4},
	0xC6: OpType{0xC6, dec, zeropage, 2, 5},
	0xD6: OpType{0xD6, dec, zeropageX, 2, 6},
	0xCE: OpType{0xCE, dec, absolute, 3, 3},
	0xDE: OpType{0xDE, dec, absoluteX, 3, 7},
	0xCA: OpType{0xCA, dex, implied, 1, 2},
	0x88: OpType{0x88, dey, implied, 1, 2},
	0x49: OpType{0x49, eor, immediate, 2, 2},
	0x45: OpType{0x45, eor, zeropage, 2, 3},
	0x55: OpType{0x55, eor, zeropageX, 2, 4},
	0x4D: OpType{0x4D, eor, absolute, 3, 4},
	0x5D: OpType{0x5D, eor, absoluteX, 3, 4},
	0x59: OpType{0x59, eor, absoluteY, 3, 4},
	0x41: OpType{0x41, eor, indirectX, 2, 6},
	0x51: OpType{0x51, eor, indirectY, 2, 5},
	0xE6: OpType{0xE6, inc, zeropage, 2, 5},
	0xF6: OpType{0xF6, inc, zeropageX, 2, 6},
	0xEE: OpType{0xEE, inc, absolute, 3, 6},
	0xFE: OpType{0xFE, inc, absoluteX, 3, 7},
	0xE8: OpType{0xE8, inx, implied, 1, 2},
	0xC8: OpType{0xC8, iny, implied, 1, 2},
	0x4C: OpType{0x4C, jmp, absolute, 3, 3},
	0x6C: OpType{0x6C, jmp, indirect, 3, 5},
	0x20: OpType{0x20, jsr, absolute, 3, 6},
	0xA9: OpType{0xA9, lda, immediate, 2, 2},
	0xA5: OpType{0xA5, lda, zeropage, 2, 3},
	0xB5: OpType{0xB5, lda, zeropageX, 2, 4},
	0xAD: OpType{0xAD, lda, absolute, 3, 4},
	0xBD: OpType{0xBD, lda, absoluteX, 3, 4},
	0xB9: OpType{0xB9, lda, absoluteY, 3, 4},
	0xA1: OpType{0xA1, lda, indirectX, 2, 6},
	0xB1: OpType{0xB1, lda, indirectY, 2, 5},
	0xA2: OpType{0xA2, ldx, immediate, 2, 2},
	0xA6: OpType{0xA6, ldx, zeropage, 2, 3},
	0xB6: OpType{0xB6, ldx, zeropageY, 2, 4},
	0xAE: OpType{0xAE, ldx, absolute, 3, 4},
	0xBE: OpType{0xBE, ldx, absoluteY, 3, 4},
	0xA0: OpType{0xA0, ldy, immediate, 2, 2},
	0xA4: OpType{0xA4, ldy, zeropage, 2, 3},
	0xB4: OpType{0xB4, ldy, zeropageX, 2, 4},
	0xAC: OpType{0xAC, ldy, absolute, 3, 4},
	0xBC: OpType{0xBC, ldy, absoluteX, 3, 4},
	0x4A: OpType{0x4A, lsr, accumulator, 1, 2},
	0x46: OpType{0x46, lsr, zeropage, 2, 5},
	0x56: OpType{0x56, lsr, zeropageX, 2, 6},
	0x4E: OpType{0x4E, lsr, absolute, 3, 6},
	0x5E: OpType{0x5E, lsr, absoluteX, 3, 7},
	0xEA: OpType{0xEA, nop, implied, 1, 2},
	0x09: OpType{0x09, ora, immediate, 2, 2},
	0x05: OpType{0x05, ora, zeropage, 2, 3},
	0x15: OpType{0x15, ora, zeropageX, 2, 4},
	0x0D: OpType{0x0D, ora, absolute, 3, 4},
	0x1D: OpType{0x1D, ora, absoluteX, 3, 4},
	0x19: OpType{0x19, ora, absoluteY, 3, 4},
	0x01: OpType{0x01, ora, indirectX, 2, 6},
	0x11: OpType{0x11, ora, indirectY, 2, 5},
	0x48: OpType{0x48, pha, implied, 1, 3},
	0x08: OpType{0x08, php, implied, 1, 3},
	0x68: OpType{0x68, pla, implied, 1, 4},
	0x28: OpType{0x28, php, implied, 1, 4},
	0x2A: OpType{0x2A, rol, accumulator, 1, 2},
	0x26: OpType{0x26, rol, zeropage, 2, 5},
	0x36: OpType{0x36, rol, zeropageX, 2, 6},
	0x2E: OpType{0x2E, rol, absolute, 3, 6},
	0x3E: OpType{0x3E, rol, absoluteX, 3, 7},
	0x6A: OpType{0x6A, ror, accumulator, 1, 2},
	0x66: OpType{0x66, ror, zeropage, 2, 5},
	0x76: OpType{0x76, ror, zeropageX, 2, 6},
	0x6E: OpType{0x6E, ror, absolute, 3, 6},
	0x7E: OpType{0x7E, ror, absoluteX, 3, 7},
	0x40: OpType{0x40, rti, implied, 1, 6},
	0x60: OpType{0x60, rts, implied, 1, 6},
	0xE9: OpType{0xE9, sbc, immediate, 2, 2},
	0xE5: OpType{0xE5, sbc, zeropage, 2, 3},
	0xF5: OpType{0xF5, sbc, zeropageX, 2, 4},
	0xED: OpType{0xED, sbc, absolute, 3, 4},
	0xFD: OpType{0xFD, sbc, absoluteX, 3, 4},
	0xF9: OpType{0xF9, sbc, absoluteY, 3, 4},
	0xE1: OpType{0xE1, sbc, indirectX, 2, 6},
	0xF1: OpType{0xF1, sbc, indirectY, 2, 5},
	0x38: OpType{0x38, sec, implied, 1, 2},
	0xF8: OpType{0xF8, sed, implied, 1, 2},
	0x78: OpType{0x78, sei, implied, 1, 2},
	0x85: OpType{0x85, sta, zeropage, 2, 3},
	0x95: OpType{0x95, sta, zeropageX, 2, 4},
	0x8D: OpType{0x8D, sta, absolute, 3, 4},
	0x9D: OpType{0x9D, sta, absoluteX, 3, 5},
	0x99: OpType{0x99, sta, absoluteY, 3, 5},
	0x81: OpType{0x81, sta, indirectX, 2, 6},
	0x91: OpType{0x91, sta, indirectY, 2, 6},
	0x86: OpType{0x86, stx, zeropage, 2, 3},
	0x96: OpType{0x96, stx, zeropageY, 2, 4},
	0x8E: OpType{0x8E, stx, absolute, 3, 4},
	0x84: OpType{0x84, sty, zeropage, 2, 3},
	0x94: OpType{0x94, sty, zeropageX, 2, 4},
	0x8C: OpType{0x8C, sty, absolute, 3, 4},
	0xAA: OpType{0xAA, tax, implied, 1, 2},
	0xA8: OpType{0xA8, tay, implied, 1, 2},
	0xBA: OpType{0xBA, tsx, implied, 1, 2},
	0x8A: OpType{0x8A, txa, implied, 1, 2},
	0x9A: OpType{0x9A, txs, implied, 1, 2},
	0x98: OpType{0x98, tya, implied, 1, 2},
	0xFF: OpType{0xFF, _end, implied, 1, 1},
}