8051 Program - validate acc for ascii hex

; Description:

; Acc Contains An ASCII Value. Determine If Valid Hex Digit Or Not.

; If Not, Return Acc Trashed, And CY == 1. If Digit Is Valid, Return

; CY == 0.

;

; Entry Requirements:

; Acc Has ASCII Hex Value To Validate

;

; On Exit:

; CY == 0 If Acc = '0'..'9', 'a'..'f', 'A'..'F', CY == 1 If Not

;

; Affected:

; PSW.CY

;

; Stack:

; 2 Bytes, Not Including Space Used By Called Routines

;

; Comments:

; None

;

UTIL_VALHXDG:
	call UTIL_TOUPPER	; Make Upper Case
	cjne a,#'0',loop1	; If < '0', Return CY == 1
loop1:	jc loop8	;
	cjne a,#'9',loop2	; If <= '9', Return CY == 0
	jmp loop7	;
loop2:	jc loop7	;
	cjne a,#'A',loop3	; If < 'A', Return CY == 1
loop3:	jc loop8	;
	cjne a,#'F',loop4	; If > 'F', Return CY == 1
	jmp loop5	;
loop4:	jnc loop8	;
loop5:		;
		;
loop7:	clr c	; CY == 0 Means Good Digit
	ret	; Return To Caller
		;
loop8:	setb c	; CY == 1 Means Bad Digit
	ret	; Return To Caller

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

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Related topics:
8051 Program - validate acc for ascii decimal   |   8051 Program - validate acc for A..Z, a..z, 0..9   |   8051 Program - validate string for A..Z, a..z, 0..9   |   8051 Program - memory subroutines   |   8051 Program - math subroutines   |   8051 Program - conversion subroutines

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List of topics: 8051

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