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=={{header|Z80 Assembly}}==

===Zilog Z80===

This example code will not work on the Game Boy, as the Game Boy does not have the <code>RLD</code> or </code>RRD</code> instructions.

<syntaxhighlight lang="z80">PrintChar equ &BB5A ;address of Amstrad CPC firmware routine, writes accumulator to stdout.

org &1000

ld hl,myarray_end-1 ;HL must point to the last byte in the array.

ld b,9 ;byte count

call RLCA_RANGE

ld hl,myarray_end-1

ld b,9

call RLCA_RANGE

ld hl,myarray_end-1

ld b,9

call RLCA_RANGE

ld hl,myarray

jp PrintString

;ret

myarray:

;pre-convert these numbers to ascii so that the job is easier.

byte &31,&32,&33,&34,&35,&36,&37,&38,&39

myarray_end:

byte 0 ;null terminator

RLCA_RANGE: ;DOESN'T WORK ON GAME BOY

;rotates a range of memory, e.g. &1000 = &23,&45,&67,&89 > &45,&67,&89,&23

;point HL at the end of the memory range this time.

ld a,(hl)

push hl

push bc

loop_RLCA_RANGE_FIRST:

RLD

DEC HL

djnz loop_RLCA_RANGE_FIRST

pop bc

pop hl

push hl

push bc

loop_RLCA_RANGE_SECOND:

RLD

DEC HL

djnz loop_RLCA_RANGE_SECOND

pop bc

pop hl

RLD

ret

PrintString:

ld a,(hl)

or a

ret z

call PrintChar

inc hl

jr PrintString</syntaxhighlight>

{{out}}

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