Editing Zilog Z8000 (section)

=== Example code ===
The following Z8000 assembly source code is for a subroutine named <code>MEMCPY</code> that copies a block of data words from one location to another. The data block is copied one word at a time, and the data movement and looping logic utilizes 16-bit operations. It demonstrates a variety of instructions but in practice it would not be coded this way as the Z8000 has a single instruction that will replace this entire subroutine: <code>LDIR</code>. The sample code will move one word every 34 cycles. Substituting the <code>LDIR</code> instruction will move a word in only 9 cycles.
<!--This was assembled by brain so it may contain errors. I realize two instructions and some cycles could be saved by using POP @R2,@R1 to move the data but that would obfuscate the example.-->
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|<syntaxhighlight lang="text">

 
 
 
 
 
 
 
 
 
 
 

 
 
 
 1000
 1000 93F4
 1002
 1002 2114
 1004 2F24
 1006 A911
 1008 A921
 100A F285
 100C
 100C 97F4
 100E 9E08
 1010
</syntaxhighlight>
|<syntaxhighlight lang="tasm">
 ; memcpy --
 ; Copy a block of memory from one location to another.
 ; This routine is the equivalent of
 ; LDIR @R2,@R1,R0 (LDIR @dst,@src,cnt)
 ;
 ; Entry registers
 ; R1 - Address of source data block
 ; R2 - Address of destination data block
 ; R0 - Number of words to copy
 ;
 ; Return registers
 ; R1 - First word after source data block
 ; R2 - First word after destination data block
 ; R0 - Zero
 
             ORG     1000h       ;Origin at 1000h
 MEMCPY:     PUSH    @R15,R4     ;Save temp register like LDIR
 
 LOOP:       LD      R4,@R1      ;Load source word
             LD      @R2,R4      ;save it
             INC     R1,#2       ;Bump source by 2 for words
             INC     R2,#2       ;Bump dest pointer by 2
             DJNZ    R0,LOOP     ;Bump count, loop if != 0
             
             POP     R4,@R15     ;Restore temp register
             RET
             END
</syntaxhighlight>
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