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[drbars]

Оставлю пример здесь. Зеркалирование байта, другой способ.

; Mirror byte Z80 example 1

	LD HL,BYTE		; Set pointer to byte
	LD DE,#5533 		; Masks to registers
	LD (HL),#0F		; Set byte to memory (for example)

;----------------------------------------------------------------------
; 21 bytes, 103 t.
	LD A,(HL)
	AND D
	ADD A,A
	LD C,A
	LD A,(HL)
	RRA
	AND D
	OR C
	LD B,A
	RRA
	RRA
	AND E
	LD C,A
	LD A,B
	AND E
	ADD A,A
	ADD A,A
	OR C
	LD (HL),A
	RRD
;----------------------------------------------------------------------

   	LD A,(HL)		; Get result from memory to reg A
	RET


;----------------------------------------------------------------------
; Mirror byte Z80 example 2
; 17 bytes, 66 t.
	LD C,A
	RLCA
	RLCA
	XOR C
	AND %10101010
	XOR C
	LD C,A
	RLCA
	RLCA
	RLCA
	RRC C
	XOR C
	AND %01100110
	XOR C
;----------------------------------------------------------------------
; Get result to reg A