8051 Program - compare dptr to 16bit iram value

; Description:

; R0 Points To A 16 Bit Location To Compare To DPTR. Return CY == 1

; If DPTR > @R0, Else CY == 0 If DPTR <= @R0. The Operation Is

; @R0 - DPTR.

;

; Entry Requirements:

; DPTR With Value To Be Compared Against

; R0 Pointing To 16 Bit Location In Internal RAM To Compare

;

; On Exit:

; CY Set Accordingly

;

; Affected:

; PSW.CY, PSW.Z, PSW.P, Acc

;

; Stack:

; 0 Bytes, Not Including Space Used By Called Routines

;

; Comments:

; Might Be A Good Idea To Save The Accumulator

UTIL_UCOMPARE16:
	clr c	; Clear For Subtract
	inc r0	; Point To Low Byte
	mov a,@r0	; Get Low Byte
	subb a,dpl	; Subtract DPL
	dec r0	; Point To High Byte
	mov a,@r0	; Get High Byte
	subb a,dph	; Subtract DPH
	ret	; Return To Caller

Source: Assorted Utilities, John C. Wren 11/23/96

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List of topics: 8051

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