CPIR

CPIR

Compare and Increment with Repeat

Description

Performs cpi until either A = (HL) or BC = 0.

cp a,(hl)
inc hl
dec bc
jr nz,-7
ret po
jr -10

Uses

• Finding a certain letter in a string (or other similar tasks)

Results

Register/Flag	16-bit (non-ADL)	24-bit (ADL)
S flag	Set if result is negative; else reset
Z flag	Set if A = (HL); else reset
H flag	Set if borrow from bit 4; else reset
P/V flag	Set if BC ≠ 0 after the operation; else reset
N flag	Set
C flag	Not affected

Allowed Instructions

Instruction	Opcode	CC (ADL/non-ADL)	CC (.S)	CC (.L)
cpir	$ED, $B9	2F + (Iterations)*(1R + 2) - 1 where Iterations is the number of iterations of cpi before either A = (HL) or BC = 0	3F + (Iterations)*(1R + 2) - 1	3F + (Iterations)*(1R + 2) - 1

Notes

• Interrupts can be triggered while this instruction is in progress (unless they are disabled using DI, of course).

See Also

CP, CPD, CPDR, CPI, LDIR