From 6d800a80eaa2a221ee44617fdd702bf7c92f22ed Mon Sep 17 00:00:00 2001 From: Ludovic Courtès Date: Sat, 9 Jun 2012 16:34:18 +0200 Subject: Add `base16-string->bytevector'. * guix/utils.scm (base16-string->bytevector): New procedure. * tests/utils.scm ("bytevector->base16-string->bytevector"): New test. --- guix/utils.scm | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'guix/utils.scm') diff --git a/guix/utils.scm b/guix/utils.scm index 65e89a0e1b..77ed9ce6ee 100644 --- a/guix/utils.scm +++ b/guix/utils.scm @@ -35,6 +35,7 @@ bytevector->base16-string base32-string->bytevector nix-base32-string->bytevector + base16-string->bytevector sha256 %nixpkgs-directory @@ -327,6 +328,33 @@ starting from the right of S." (loop (+ 1 i) (cons (vector-ref chars (bytevector-u8-ref bv i)) r)))))) +(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))) + ;;; ;;; Hash. -- cgit v1.2.3