Loop Control with CX Counter (loop, loopnz, loopz)

loop    	disp8
loopnz  	disp8
loopne  	disp8
loopz   	disp8
loope   	disp8

Operation

decrement count; jump to disp8 if count not equal 0

decrement count; jump to disp8 if count not equal 0 and ZF = 0

decrement count; jump to disp8 if count not equal 0 and ZF = 1

Description

loop decrements the count register; the flags register remains unchanged. Conditions are checked for by the particular form of loop you used. If the conditions match, a short jump is made to the address specified by the disp8 operand. The range of the disp8 operand, relative to the current instruction, is +127 decimal bytes to -128 decimal bytes.

loop instructions provide iteration control and combine loop index management with conditional branching. Prior to using the loop instruction, load the count register with an unsigned iteration count. Then, add the loop instruction at the end of a series of instructions to be iterated. The disp8 operand points to the beginning of the iterative loop.

Example

Decrement the count register and when the count is not equal to zero, jump short to the disp8 location.

loopne .-126