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