.TITLE	NBLEN - Return the non-blank length of a string

;
;	Author:	Chris Chaundy
;	Date:	02-Jun-1981
;
;+
; This procedure finds the length of a string excluding trailing spaces.
;
; Calling sequence:
;
;	length = NBLEN (str_dsc)
;
; Inputs:
;	str_dsc		- string descriptor
;
; Outputs:
;	length		- length of string
;
; Side-effects:
;	none
;-

STR_DSC	= 4

	.PSECT	_STR_CODE PIC,USR,CON,REL,LCL,SHR,EXE,RD,NOWRT

	.ENTRY	NBLEN,^M<R2,R3,R4>

;	Initialization

	MOVQ	@STR_DSC(AP),R0		; R0 <15:0> = len, R1 = adr of STR_DSC
	MOVQ	R0,R2			; save the descriptor in R2, R3

;	Find last spaces in string

10$:	LOCC	#^A' ',R0,(R1)		; find space
	BEQL	20$			; input string exhausted
	MOVL	R1,R4			; note current position in string
	SKPC	#^A' ',R0,(R1)		; skip over it (or them)
	BNEQ	10$			; loop if more string to go

;	Find the length

	SUBL3	R3,R4,R0		; return length in R0
	RET

;	No trailing blanks so return original length

20$:	MOVZWL	R2,R0			; set output length
	RET

	.END