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ASSEMBLY & COMPILE TOOLS/PLM VAX COMPILER/util86/bit.mar

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+        .TITLE  BIT. (UTIL-VAX Library Routine BIT)
+;-----------------------------------------------------------------------
+;
+;               D I S C L A I M E R   N O T I C E
+;               -------------------   -----------
+;
+;  This document and/or portions of the material and data furnished
+;  herewith, was developed under sponsorship of the U. S. Government.
+;  Neither the U.S. nor the U.S.D.O.E., nor the Leland Stanford Junior
+;  University, nor their employees, nor their respective contractors,
+;  subcontractors, or their employees, makes any warranty, express or
+;  implied, or assumes any liability or responsibility for accuracy,
+;  completeness or usefulness of any information, apparatus, product
+;  or process disclosed, or represents that its use will not infringe
+;  privately-owned rights.  Mention of any product, its manufacturer,
+;  or suppliers shall not, nor is it intended to, imply approval, dis-
+;  approval, or fitness for any particular use.  The U. S. and the
+;  University at all times retain the right to use and disseminate same
+;  for any purpose whatsoever.  Such distribution shall be made by the
+;  National Energy Software Center at the Argonne National Laboratory
+;  and only subject to the distributee furnishing satisfactory proof
+;  that he has a valid license from the Intel Corporation in effect.
+;
+;-----------------------------------------------------------------------
+ 
+        .PSECT  UTIL_CODE,RD,NOWRT,EXE,GBL,CON,LONG
+ 
+;  BIT: PROCEDURE (NUMBER,PRTX) BYTE PUBLIC;
+;	DECLARE NUMBER BYTE, PTRX ADDRESS;
+;  END BIT;
+;
+;  Beware that bits in this routine are numbered 0-7, where 0 is
+;  the high order bit in a byte, and 7 is the low order bit!!!!
+ 
+	.ENTRY	BIT,^M<>
+	MOVZBL	4(AP),R0	; R0 <- number.
+	MOVL	8(AP),R1	; R1 -> array.
+	CMPB	R0,(R1)		; Check for number > max.
+	BLEQU	ITS_OK
+	CLRL	R0		; Return FALSE if number > max.
+	RET
+ITS_OK:	XORB2	#7,R0		; Reverse sense of bit # within byte.
+	EXTV	R0,#1,1(R1),R0	; Extract selected bit and extend sign.
+	RET			; Return TRUE or FALSE.
+ 
+	.END