mirror of
https://git.in.rschanz.org/ryan77627/guix.git
synced 2024-11-18 12:47:33 -05:00
a87d8c912d
This makes bytevector->base16-string two times faster. * guix/base16.scm (bytevector->base16-string): Use utf8->string and iteration instead of string-concatenate and named let. Signed-off-by: Ludovic Courtès <ludo@gnu.org>
85 lines
3.2 KiB
Scheme
85 lines
3.2 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
|
||
;;; Copyright © 2012, 2014, 2017 Ludovic Courtès <ludo@gnu.org>
|
||
;;; Copyright © 2021 Maxime Devos <maximedevos@telenet.be>
|
||
;;;
|
||
;;; This file is part of GNU Guix.
|
||
;;;
|
||
;;; GNU Guix is free software; you can redistribute it and/or modify it
|
||
;;; under the terms of the GNU General Public License as published by
|
||
;;; the Free Software Foundation; either version 3 of the License, or (at
|
||
;;; your option) any later version.
|
||
;;;
|
||
;;; GNU Guix 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 General Public License for more details.
|
||
;;;
|
||
;;; You should have received a copy of the GNU General Public License
|
||
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
|
||
|
||
(define-module (guix base16)
|
||
#:use-module (srfi srfi-1)
|
||
#:use-module (srfi srfi-26)
|
||
#:use-module (srfi srfi-60)
|
||
#:use-module (rnrs bytevectors)
|
||
#:use-module (ice-9 vlist)
|
||
#:use-module (ice-9 format)
|
||
#:export (bytevector->base16-string
|
||
base16-string->bytevector))
|
||
|
||
;;;
|
||
;;; Base 16.
|
||
;;;
|
||
|
||
(define (bytevector->base16-string bv)
|
||
"Return the hexadecimal representation of BV's contents."
|
||
(define len (bytevector-length bv))
|
||
(define utf8 (make-bytevector (* len 2)))
|
||
(let-syntax ((base16-octet-pairs
|
||
(lambda (s)
|
||
(syntax-case s ()
|
||
(_
|
||
(string->utf8
|
||
(string-concatenate
|
||
(unfold (cut > <> 255)
|
||
(lambda (n)
|
||
(format #f "~2,'0x" n))
|
||
1+
|
||
0))))))))
|
||
(define octet-pairs base16-octet-pairs)
|
||
(let loop ((i 0))
|
||
(when (< i len)
|
||
(bytevector-u16-native-set!
|
||
utf8 (* 2 i)
|
||
(bytevector-u16-native-ref octet-pairs
|
||
(* 2 (bytevector-u8-ref bv i))))
|
||
(loop (+ i 1))))
|
||
(utf8->string utf8)))
|
||
|
||
(define base16-string->bytevector
|
||
(let ((chars->value (fold (lambda (i r)
|
||
(vhash-consv (string-ref (number->string i 16)
|
||
0)
|
||
i r))
|
||
vlist-null
|
||
(iota 16))))
|
||
(lambda (s)
|
||
"Return the bytevector whose hexadecimal representation is string S."
|
||
(define bv
|
||
(make-bytevector (quotient (string-length s) 2) 0))
|
||
|
||
(string-fold (lambda (chr i)
|
||
(let ((j (quotient i 2))
|
||
(v (and=> (vhash-assv chr chars->value) cdr)))
|
||
(if v
|
||
(if (zero? (logand i 1))
|
||
(bytevector-u8-set! bv j
|
||
(arithmetic-shift v 4))
|
||
(let ((w (bytevector-u8-ref bv j)))
|
||
(bytevector-u8-set! bv j (logior v w))))
|
||
(error "invalid hexadecimal character" chr)))
|
||
(+ i 1))
|
||
0
|
||
s)
|
||
bv)))
|
||
|