From 555f6d6e75948601f763d84410cb4148786b0059 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Wed, 22 Apr 2015 19:55:07 -0700
Subject: mpi-to-double patch

* mpi/mpi.c (mp_to_double): New function.

* mpi/mpi.h (mp_to_double): Declared.
---
 mpi/mpi.c | 24 ++++++++++++++++++++++++
 mpi/mpi.h |  5 +++++
 2 files changed, 29 insertions(+)

(limited to 'mpi')

diff --git a/mpi/mpi.c b/mpi/mpi.c
index 8ea4b1ba..33815a9d 100644
--- a/mpi/mpi.c
+++ b/mpi/mpi.c
@@ -14,6 +14,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
+#include <math.h>
 
 typedef unsigned char mem_t;
 extern mem_t *chk_calloc(size_t n, size_t size);
@@ -2333,6 +2334,29 @@ X:
 
 /* }}} */
 
+mp_err mp_to_double(mp_int *mp, double *d)
+{
+  int ix;
+  mp_size used = USED(mp);
+  mp_digit *dp = DIGITS(mp);
+  static double mult;
+  double out = dp[used - 1];
+
+  if (!mult)
+    mult = pow(2.0, MP_DIGIT_BIT);
+
+  for (ix = (int) used - 2; ix >= 0; ix--) {
+    out = out * mult;
+    out += (double) dp[ix];
+  }
+
+  if (SIGN(mp) == MP_NEG)
+    out = -out;
+
+  *d = out;
+  return MP_OKAY;
+}
+
 /*------------------------------------------------------------------------*/
 /* {{{ mp_print(mp, ofp) */
 
diff --git a/mpi/mpi.h b/mpi/mpi.h
index ba255419..c6136c15 100644
--- a/mpi/mpi.h
+++ b/mpi/mpi.h
@@ -186,6 +186,11 @@ mp_err mp_xgcd(mp_int *a, mp_int *b, mp_int *g, mp_int *x, mp_int *y);
 mp_err mp_invmod(mp_int *a, mp_int *m, mp_int *c);
 #endif /* end MP_NUMTH */
 
+/*------------------------------------------------------------------------*/
+/* Conversions                                                            */
+
+mp_err mp_to_double(mp_int *mp, double *d);
+
 /*------------------------------------------------------------------------*/
 /* Input and output                                                       */
 
-- 
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