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93da406f33
* module/rnrs/arithmetic/bitwise.scm (bitwise-if, bitwise-length, bitwise-first-bit-set, bitwise-bit-field, bitwise-reverse-bit-field): Replace these with aliases to the identical SRFI-60 operators 'bitwise-if', 'integer-length', 'first-set-bit', 'bit-field', and 'reverse-bit-field'. (bitwise-copy-bit, bitwise-copy-bit-field, bitwise-rotate-bit-field): Reimplement these based upon the similar SRFI-60 operators 'copy-bit', 'copy-bit-field', and 'rotate-bit-field'. * test-suite/tests/r6rs-arithmetic-bitwise.test (bitwise-copy-bit): Fix test to conform to the specification, which requires the third argument to be either 0 or 1. * test-suite/tests/r6rs-arithmetic-fixnums.test (fxcopy-bit): Fix test to conform to the specification, which requires the third argument to be either 0 or 1.
92 lines
3.1 KiB
Scheme
92 lines
3.1 KiB
Scheme
;;; bitwise.scm --- The R6RS bitwise arithmetic operations library
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;; Copyright (C) 2010, 2013 Free Software Foundation, Inc.
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;;
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;; This library is free software; you can redistribute it and/or
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;; modify it under the terms of the GNU Lesser General Public
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;; License as published by the Free Software Foundation; either
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;; version 3 of the License, or (at your option) any later version.
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;;
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;; This library is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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;; Lesser General Public License for more details.
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;;
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;; You should have received a copy of the GNU Lesser General Public
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;; License along with this library; if not, write to the Free Software
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;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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(library (rnrs arithmetic bitwise (6))
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(export bitwise-not
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bitwise-and
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bitwise-ior
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bitwise-xor
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bitwise-if
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bitwise-bit-count
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bitwise-length
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bitwise-first-bit-set
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bitwise-bit-set?
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bitwise-copy-bit
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bitwise-bit-field
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bitwise-copy-bit-field
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bitwise-arithmetic-shift
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bitwise-arithmetic-shift-left
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bitwise-arithmetic-shift-right
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bitwise-rotate-bit-field
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bitwise-reverse-bit-field)
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(import (rnrs base (6))
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(rnrs control (6))
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(rename (only (srfi srfi-60) bitwise-if
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integer-length
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first-set-bit
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copy-bit
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bit-field
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copy-bit-field
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rotate-bit-field
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reverse-bit-field)
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(integer-length bitwise-length)
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(first-set-bit bitwise-first-bit-set)
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(bit-field bitwise-bit-field)
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(reverse-bit-field bitwise-reverse-bit-field))
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(rename (only (guile) lognot
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logand
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logior
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logxor
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logcount
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logbit?
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modulo
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ash)
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(lognot bitwise-not)
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(logand bitwise-and)
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(logior bitwise-ior)
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(logxor bitwise-xor)
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(ash bitwise-arithmetic-shift)))
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(define (bitwise-bit-count ei)
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(if (negative? ei)
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(bitwise-not (logcount ei))
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(logcount ei)))
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(define (bitwise-bit-set? ei1 ei2) (logbit? ei2 ei1))
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(define (bitwise-copy-bit ei1 ei2 ei3)
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;; The specification states that ei3 should be either 0 or 1.
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;; However, other values have been tolerated by both Guile 2.0.x and
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;; the sample implementation given the R6RS library document, so for
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;; backward compatibility we continue to permit it.
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(copy-bit ei2 ei1 (logbit? 0 ei3)))
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(define (bitwise-copy-bit-field ei1 ei2 ei3 ei4)
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(copy-bit-field ei1 ei4 ei2 ei3))
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(define (bitwise-rotate-bit-field ei1 ei2 ei3 ei4)
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(rotate-bit-field ei1 ei4 ei2 ei3))
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(define bitwise-arithmetic-shift-left bitwise-arithmetic-shift)
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(define (bitwise-arithmetic-shift-right ei1 ei2)
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(bitwise-arithmetic-shift ei1 (- ei2))))
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