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authorWerner Koch <wk@gnupg.org>1997-11-26 21:06:44 +0000
committerWerner Koch <wk@gnupg.org>1997-11-26 21:06:44 +0000
commit55aefe3378aea76c3bfe3bf290d8b7d74bed133a (patch)
treef7b025ec8697d87260c98c05415bf95f901fd099 /mpi/mpi-inline.h
parent7927452093826608e9e29f3ac13166415dabf46c (diff)
downloadlibgcrypt-55aefe3378aea76c3bfe3bf290d8b7d74bed133a.tar.gz
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+/* mpi-inline.h - Internal to the Multi Precision Integers
+ * Copyright (c) 1997 by Werner Koch (dd9jn)
+ * Copyright (C) 1994, 1996 Free Software Foundation, Inc.
+ *
+ * This file is part of G10.
+ *
+ * G10 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * G10 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ *
+ * Note: This code is heavily based on the GNU MP Library.
+ * Actually it's the same code with only minor changes in the
+ * way the data is stored; this is to support the abstraction
+ * of an optional secure memory allocation which may be used
+ * to avoid revealing of sensitive data due to paging etc.
+ * The GNU MP Library itself is published under the LGPL;
+ * however I decided to publish this code under the plain GPL.
+ */
+
+#ifndef G10_MPI_INLINE_H
+#define G10_MPI_INLINE_H
+
+
+extern __inline__ mpi_limb_t
+mpihelp_add_1( mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
+ mpi_size_t s1_size, mpi_limb_t s2_limb)
+{
+ mpi_limb_t x;
+
+ x = *s1_ptr++;
+ s2_limb += x;
+ *res_ptr++ = s2_limb;
+ if( s2_limb < x ) { /* sum is less than the left operand: handle carry */
+ while( --s1_size ) {
+ x = *s1_ptr++ + 1; /* add carry */
+ *res_ptr++ = x; /* and store */
+ if( x ) /* not 0 (no overflow): we can stop */
+ goto leave;
+ }
+ return 1; /* return carry (size of s1 to small) */
+ }
+
+ leave:
+ if( res_ptr != s1_ptr ) { /* not the same variable */
+ mpi_size_t i; /* copy the rest */
+ for( i=0; i < s1_size-1; i++ )
+ res_ptr[i] = s1_ptr[i];
+ }
+ return 0; /* no carry */
+}
+
+
+
+extern __inline__ mpi_limb_t
+mpihelp_add(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size,
+ mpi_ptr_t s2_ptr, mpi_size_t s2_size)
+{
+ mpi_limb_t cy = 0;
+
+ if( s2_size )
+ cy = mpihelp_add_n( res_ptr, s1_ptr, s2_ptr, s2_size );
+
+ if( s1_size - s2_size )
+ cy = mpihelp_add_1( res_ptr + s2_size, s1_ptr + s2_size,
+ s1_size - s2_size, cy);
+ return cy;
+}
+
+
+extern __inline__ mpi_limb_t
+mpihelp_sub_1(mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
+ mpi_size_t s1_size, mpi_limb_t s2_limb )
+{
+ mpi_limb_t x;
+
+ x = *s1_ptr++;
+ s2_limb = x - s2_limb;
+ *res_ptr++ = s2_limb;
+ if( s2_limb > x ) {
+ while( --s1_size ) {
+ x = *s1_ptr++;
+ *res_ptr++ = x - 1;
+ if( x )
+ goto leave;
+ }
+ return 1;
+ }
+
+ leave:
+ if( res_ptr != s1_ptr ) {
+ mpi_size_t i;
+ for( i=0; i < s1_size-1; i++ )
+ res_ptr[i] = s1_ptr[i];
+ }
+ return 0;
+}
+
+
+
+extern __inline__ mpi_limb_t
+mpihelp_sub( mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr, mpi_size_t s1_size,
+ mpi_ptr_t s2_ptr, mpi_size_t s2_size)
+{
+ mpi_limb_t cy = 0;
+
+ if( s2_size )
+ cy = mpihelp_sub_n(res_ptr, s1_ptr, s2_ptr, s2_size);
+
+ if( s1_size - s2_size )
+ cy = mpihelp_sub_1(res_ptr + s2_size, s1_ptr + s2_size,
+ s1_size - s2_size, cy);
+ return cy;
+}
+
+
+
+#endif /*G10_MPI_INLINE_H*/