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path: root/pwmanager/libcrypt/mpi/mpi-scan.c
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-rw-r--r--pwmanager/libcrypt/mpi/mpi-scan.c132
1 files changed, 132 insertions, 0 deletions
diff --git a/pwmanager/libcrypt/mpi/mpi-scan.c b/pwmanager/libcrypt/mpi/mpi-scan.c
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+++ b/pwmanager/libcrypt/mpi/mpi-scan.c
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+/* mpi-scan.c - MPI functions
+ * Copyright (C) 1998, 2001, 2002, 2003 Free Software Foundation, Inc.
+ *
+ * This file is part of Libgcrypt.
+ *
+ * Libgcrypt 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 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * Libgcrypt 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 program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "mpi-internal.h"
+#include "longlong.h"
+
+/****************
+ * Scan through an mpi and return byte for byte. a -1 is returned to indicate
+ * the end of the mpi. Scanning is done from the lsb to the msb, returned
+ * values are in the range of 0 .. 255.
+ *
+ * FIXME: This code is VERY ugly!
+ */
+int
+_gcry_mpi_getbyte( gcry_mpi_t a, unsigned idx )
+{
+ int i, j;
+ unsigned n;
+ mpi_ptr_t ap;
+ mpi_limb_t limb;
+
+ ap = a->d;
+ for(n=0,i=0; i < a->nlimbs; i++ ) {
+ limb = ap[i];
+ for( j=0; j < BYTES_PER_MPI_LIMB; j++, n++ )
+ if( n == idx )
+ return (limb >> j*8) & 0xff;
+ }
+ return -1;
+}
+
+
+/****************
+ * Put a value at position IDX into A. idx counts from lsb to msb
+ */
+void
+_gcry_mpi_putbyte( gcry_mpi_t a, unsigned idx, int xc )
+{
+ int i, j;
+ unsigned n;
+ mpi_ptr_t ap;
+ mpi_limb_t limb, c;
+
+ c = xc & 0xff;
+ ap = a->d;
+ for(n=0,i=0; i < a->alloced; i++ ) {
+ limb = ap[i];
+ for( j=0; j < BYTES_PER_MPI_LIMB; j++, n++ )
+ if( n == idx ) {
+ #if BYTES_PER_MPI_LIMB == 4
+ if( j == 0 )
+ limb = (limb & 0xffffff00) | c;
+ else if( j == 1 )
+ limb = (limb & 0xffff00ff) | (c<<8);
+ else if( j == 2 )
+ limb = (limb & 0xff00ffff) | (c<<16);
+ else
+ limb = (limb & 0x00ffffff) | (c<<24);
+ #elif BYTES_PER_MPI_LIMB == 8
+ if( j == 0 )
+ limb = (limb & 0xffffffffffffff00) | c;
+ else if( j == 1 )
+ limb = (limb & 0xffffffffffff00ff) | (c<<8);
+ else if( j == 2 )
+ limb = (limb & 0xffffffffff00ffff) | (c<<16);
+ else if( j == 3 )
+ limb = (limb & 0xffffffff00ffffff) | (c<<24);
+ else if( j == 4 )
+ limb = (limb & 0xffffff00ffffffff) | (c<<32);
+ else if( j == 5 )
+ limb = (limb & 0xffff00ffffffffff) | (c<<40);
+ else if( j == 6 )
+ limb = (limb & 0xff00ffffffffffff) | (c<<48);
+ else
+ limb = (limb & 0x00ffffffffffffff) | (c<<56);
+ #else
+ #error please enhance this function, its ugly - i know.
+ #endif
+ if( a->nlimbs <= i )
+ a->nlimbs = i+1;
+ ap[i] = limb;
+ return;
+ }
+ }
+ abort(); /* index out of range */
+}
+
+
+/****************
+ * Count the number of zerobits at the low end of A
+ */
+unsigned
+_gcry_mpi_trailing_zeros( gcry_mpi_t a )
+{
+ unsigned n, count = 0;
+
+ for(n=0; n < a->nlimbs; n++ ) {
+ if( a->d[n] ) {
+ unsigned nn;
+ mpi_limb_t alimb = a->d[n];
+
+ count_trailing_zeros( nn, alimb );
+ count += nn;
+ break;
+ }
+ count += BITS_PER_MPI_LIMB;
+ }
+ return count;
+
+}
+
+