© Thomas Kunz 2000
SCE 574
93
Assembler
Example:
CX as a loop counter
CX as a loop counter
äWe
can take advantage of CX as a loop counter to speed up the program
MOV AX, InitialValue
MOV BX, OFFSET ArrayX
MOV CX, ArraySize
JCXZ DONE
InitLoop: MOV [BX],AX
ADD BX,2
LOOP InitLoop
...
DONE:
äOnly
CX can be used as a loop counter
äCompilers (good compilers) generate code to take advantage of
special instructions that help reduce execution time
Will count down
instead of up!
Jump only if CX=0
Same as
DEC CX
JNZ InitLoop