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;;; bitwise.scm --- The R6RS bitwise arithmetic operations library
;; Copyright (C) 2010, 2013 Free Software Foundation, Inc.
;;
;; This library is free software; you can redistribute it and/or
;; modify it under the terms of the GNU Lesser General Public
;; License as published by the Free Software Foundation; either
;; version 3 of the License, or (at your option) any later version.
;;
;; This library is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; Lesser General Public License for more details.
;;
;; You should have received a copy of the GNU Lesser General Public
;; License along with this library; if not, write to the Free Software
;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
(library (rnrs arithmetic bitwise (6))
(export bitwise-not
bitwise-and
bitwise-ior
bitwise-xor
bitwise-if
bitwise-bit-count
bitwise-length
bitwise-first-bit-set
bitwise-bit-set?
bitwise-copy-bit
bitwise-bit-field
bitwise-copy-bit-field
bitwise-arithmetic-shift
bitwise-arithmetic-shift-left
bitwise-arithmetic-shift-right
bitwise-rotate-bit-field
bitwise-reverse-bit-field)
(import (rnrs base (6))
(rnrs control (6))
(rename (only (srfi srfi-60) bitwise-if
integer-length
first-set-bit
copy-bit
bit-field
copy-bit-field
rotate-bit-field
reverse-bit-field)
(integer-length bitwise-length)
(first-set-bit bitwise-first-bit-set)
(bit-field bitwise-bit-field)
(reverse-bit-field bitwise-reverse-bit-field))
(rename (only (guile) lognot
logand
logior
logxor
logcount
logbit?
modulo
ash)
(lognot bitwise-not)
(logand bitwise-and)
(logior bitwise-ior)
(logxor bitwise-xor)
(ash bitwise-arithmetic-shift)))
(define (bitwise-bit-count ei)
(if (negative? ei)
(bitwise-not (logcount ei))
(logcount ei)))
(define (bitwise-bit-set? ei1 ei2) (logbit? ei2 ei1))
(define (bitwise-copy-bit ei1 ei2 ei3)
;; The specification states that ei3 should be either 0 or 1.
;; However, other values have been tolerated by both Guile 2.0.x and
;; the sample implementation given the R6RS library document, so for
;; backward compatibility we continue to permit it.
(copy-bit ei2 ei1 (logbit? 0 ei3)))
(define (bitwise-copy-bit-field ei1 ei2 ei3 ei4)
(copy-bit-field ei1 ei4 ei2 ei3))
(define (bitwise-rotate-bit-field ei1 ei2 ei3 ei4)
(rotate-bit-field ei1 ei4 ei2 ei3))
(define bitwise-arithmetic-shift-left bitwise-arithmetic-shift)
(define (bitwise-arithmetic-shift-right ei1 ei2)
(bitwise-arithmetic-shift ei1 (- ei2))))
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