bitget.pro
5.45 KB
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;+
; NAME:
; BITGET
;
; PURPOSE:
;
; Returns the bit value (0 or 1) of a specified bit in a supplied number.
;
; AUTHOR:
;
; FANNING SOFTWARE CONSULTING
; David Fanning, Ph.D.
; 1645 Sheely Drive
; Fort Collins, CO 80526 USA
; Phone: 970-221-0438
; E-mail: david@idlcoyote.com
; Coyote's Guide to IDL Programming: http://www.idlcoyote.com
;
; CATEGORY:
; Utilities
;
; CALLING SEQUENCE:
;
; bitValue = BitGet(number, bit)
;
; INPUT_PARAMETERS:
;
; number: The input number. Should be a scalar integer. If not, it is converted to
; one by rounding.
;
; bit: The number of the bit you are interested in. A value between 0 and 63.
; If not supplied, all 64 bit values of the number are returned. May be
; an array of bit numbers.
;
; OUTPUT_PARAMETERS:
;
; bitValue: The value, 0 or 1, of the specified bit in the number.
;
; KEYWORDS:
;
; SILENT: If set, suppresses informational messages regarding rounding operations.
;
; MODIFICATION HISTORY:
;
; Written by David W. Fanning, 14 June 2006.
;-
;******************************************************************************************;
; Copyright (c) 2008, by Fanning Software Consulting, Inc. ;
; All rights reserved. ;
; ;
; Redistribution and use in source and binary forms, with or without ;
; modification, are permitted provided that the following conditions are met: ;
; ;
; * Redistributions of source code must retain the above copyright ;
; notice, this list of conditions and the following disclaimer. ;
; * Redistributions in binary form must reproduce the above copyright ;
; notice, this list of conditions and the following disclaimer in the ;
; documentation and/or other materials provided with the distribution. ;
; * Neither the name of Fanning Software Consulting, Inc. nor the names of its ;
; contributors may be used to endorse or promote products derived from this ;
; software without specific prior written permission. ;
; ;
; THIS SOFTWARE IS PROVIDED BY FANNING SOFTWARE CONSULTING, INC. ''AS IS'' AND ANY ;
; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES ;
; OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT ;
; SHALL FANNING SOFTWARE CONSULTING, INC. BE LIABLE FOR ANY DIRECT, INDIRECT, ;
; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED ;
; TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; ;
; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ;
; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ;
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS ;
; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ;
;******************************************************************************************;
FUNCTION BitGet, value, bit, SILENT=silent
; Return to caller if something goes wrong.
On_Error, 2
; Get the data type.
theType = Size(value, /TYPE)
; Special pointer processing.
IF theType EQ 10 THEN BEGIN
theValue = *value
theType = Size(theValue, /TYPE)
ENDIF ELSE theValue = value
; Validate data type. Round any non-integer data type.
CASE 1 OF
theType LT 1: Message, 'VALUE must be defined.'
theType GT 0 AND theType LT 4:
theType GT 5 AND theType LT 10: Message, 'Wrong data type (' + Size(theValue, /TNAME) + $
') supplied for determining bit value.'
theType EQ 11: Message, 'Wrong data type supplied for determining bit value.'
theType GT 11 AND theType LT 16:
ELSE: BEGIN
IF ~Keyword_Set(silent) THEN Message, 'Converting value to INTEGER format...', /Informational
theValue = Round(theValue, /L64)
END
ENDCASE
; Make sure the value is scalar.
IF N_Elements(theValue) NE 1 THEN Message, 'Examined value must be a scalar.'
theValue = theValue[0]
exponent = 2ULL^UL64indgen(64)
; If not bit value is specifed, return all the bits in the value.
IF N_Elements(bit) EQ 0 THEN BEGIN
CASE 1 OF
theType EQ 1: RETURN, Reverse(((theValue AND exponent)/exponent)[0:7])
theType EQ 2 OR theType EQ 12: RETURN, Reverse(((theValue AND exponent)/exponent)[0:15])
theType EQ 3 OR theType EQ 13: RETURN, Reverse(((theValue AND exponent)/exponent)[0:31])
ELSE: RETURN, Reverse((theValue AND exponent)/exponent)
ENDCASE
ENDIF ELSE bit = 0 > bit < 63 ; Confine it to correct range.
; Calculate the bit value and return it.
RETURN, ((theValue AND exponent)/exponent)[bit]
END