initially checkin

1 files changed, 221 insertions, 0 deletions

diff --git a/mpi/mpi-add.c b/mpi/mpi-add.c
new file mode 100644
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--- /dev/null
+++ b/mpi/mpi-add.c
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+/* mpi-add.c  -  MPI functions
+ *	Copyright (c) 1997 by Werner Koch (dd9jn)
+ *
+ * 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
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "mpi-internal.h"
+
+
+/****************
+ * Add the unsigned integer V to the mpi-integer U and store the
+ * result in W. U and V may be the same.
+ */
+void
+mpi_add_ui(MPI w, MPI u, unsigned long v )
+{
+    mpi_ptr_t wp, up;
+    mpi_size_t usize, wsize;
+    int usign, wsign;
+
+    usize = u->nlimbs;
+    usign = u->sign;
+    wsign = 0;
+
+    /* If not space for W (and possible carry), increase space.  */
+    wsize = usize + 1;
+    if( w->alloced < wsize )
+	mpi_resize(w, wsize);
+
+    /* These must be after realloc (U may be the same as W).  */
+    up = u->d;
+    wp = w->d;
+
+    if( !usize ) {  /* simple */
+	wp[0] = v;
+	wsize = v? 1:0;
+    }
+    else if( !usign ) {  /* mpi is not negative */
+	mpi_limb_t cy;
+	cy = mpihelp_add_1(wp, up, usize, v);
+	wp[usize] = cy;
+	wsize = usize + cy;
+    }
+    else {  /* The signs are different.  Need exact comparison to determine
+	     * which operand to subtract from which.  */
+	if( usize == 1 && up[0] < v ) {
+	    wp[0] = v - up[0];
+	    wsize = 1;
+	}
+	else {
+	    mpihelp_sub_1(wp, up, usize, v);
+	    /* Size can decrease with at most one limb. */
+	    wsize = (usize - (wp[usize-1]? 0:1));
+	    wsign = 1;
+	}
+    }
+
+    w->nlimbs = wsize;
+    w->sign   = wsign;
+}
+
+
+void
+mpi_add(MPI w, MPI u, MPI v)
+{
+    mpi_ptr_t wp, up, vp;
+    mpi_size_t usize, vsize, wsize;
+    int usign, vsign, wsign;
+
+    usize = u->nlimbs;
+    vsize = v->nlimbs;
+    usign = u->sign;
+    vsign = v->sign;
+
+    if( usize < vsize ) { /* Swap U and V. */
+	{ MPI t; t = u; u = v; v = t; }
+	{ mpi_size_t t = usize; usize = vsize; vsize = t; }
+	{ int t = usign; usign = vsign; vsign = t; }
+    }
+
+    /* If not space for w (and possible carry), increase space.  */
+    wsize = usize + 1;
+    if( w->alloced < wsize )
+	mpi_resize(w, wsize);
+    wsign = 0;
+
+    /* These must be after realloc (u or v may be the same as w).  */
+    up = u->d;
+    vp = v->d;
+    wp = w->d;
+
+    if( !vsize ) {  /* simple */
+	MPN_COPY(wp, up, usize );
+	wsize = usize;
+	wsign = usign;
+    }
+    else if( usign != vsign ) { /* different sign */
+	/* This test is right since USIZE >= VSIZE */
+	if( usize != vsize ) {
+	    mpihelp_sub(wp, up, usize, vp, vsize);
+	    wsize = usize;
+	    MPN_NORMALIZE(wp, wsize);
+	    wsign = usign;
+	}
+	else if( mpihelp_cmp(up, vp, usize) < 0 ) {
+	    mpihelp_sub_n(wp, vp, up, usize);
+	    wsize = usize;
+	    MPN_NORMALIZE(wp, wsize);
+	    if( !usign )
+		wsign = 1;
+	}
+	else {
+	    mpihelp_sub_n(wp, up, vp, usize);
+	    wsize = usize;
+	    MPN_NORMALIZE(wp, wsize);
+	    if( usign )
+		wsign = 1;
+	}
+    }
+    else { /* U and V have same sign. Add them. */
+	mpi_limb_t cy = mpihelp_add(wp, up, usize, vp, vsize);
+	wp[usize] = cy;
+	wsize = usize + cy;
+	if( usign )
+	    wsize = 1;
+    }
+
+    w->nlimbs = wsize;
+    w->sign = wsign;
+}
+
+
+/****************
+ * Subtract the unsigned integer V from the mpi-integer U and store the
+ * result in W.
+ */
+void
+mpi_sub_ui(MPI w, MPI u, unsigned long v )
+{
+    mpi_ptr_t wp, up;
+    mpi_size_t usize, wsize;
+    int usign, wsign;
+
+    usize = u->nlimbs;
+    usign = u->sign;
+    wsign = 0;
+
+    /* If not space for W (and possible carry), increase space.  */
+    wsize = usize + 1;
+    if( w->alloced < wsize )
+	mpi_resize(w, wsize);
+
+    /* These must be after realloc (U may be the same as W).  */
+    up = u->d;
+    wp = w->d;
+
+    if( !usize ) {  /* simple */
+	wp[0] = v;
+	wsize = v? 1:0;
+	wsign = 1;
+    }
+    else if( usign ) {	/* mpi and v are negative */
+	mpi_limb_t cy;
+	cy = mpihelp_add_1(wp, up, usize, v);
+	wp[usize] = cy;
+	wsize = usize + cy;
+    }
+    else {  /* The signs are different.  Need exact comparison to determine
+	     * which operand to subtract from which.  */
+	if( usize == 1 && up[0] < v ) {
+	    wp[0] = v - up[0];
+	    wsize = 1;
+	    wsign = 1;
+	}
+	else {
+	    mpihelp_sub_1(wp, up, usize, v);
+	    /* Size can decrease with at most one limb. */
+	    wsize = (usize - (wp[usize-1]? 1:0));
+	}
+    }
+
+    w->nlimbs = wsize;
+    w->sign   = wsign;
+}
+
+void
+mpi_sub(MPI w, MPI u, MPI v)
+{
+    if( w == v ) {
+	MPI vv = mpi_copy(v);
+	vv->sign = !vv->sign;
+	mpi_add( w, u, vv );
+	m_free(vv);
+    }
+    else {
+	/* fixme: this is not thread-save (we temp. modify v) */
+	v->sign = !v->sign;
+	mpi_add( w, u, v );
+	v->sign = !v->sign;
+    }
+}
+
+