From c5b962387ce0bd47ee6abb058c304f8a360e988a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dag-Erling=20Sm=C3=B8rgrav?= <des@des.no>
Date: Tue, 30 Dec 2014 11:12:11 +0000
Subject: [PATCH] Add mpi_eq_abs() and mpi_eq() predicates.
---
include/cryb/mpi.h | 2 ++
lib/mpi/mpi_cmp.c | 25 ++++++++++++++++++++++++-
2 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/include/cryb/mpi.h b/include/cryb/mpi.h
index ca7d515..ba657b2 100644
--- a/include/cryb/mpi.h
+++ b/include/cryb/mpi.h
@@ -58,5 +58,7 @@ int mpi_add_abs(cryb_mpi *, cryb_mpi *, cryb_mpi *);
int mpi_sub_abs(cryb_mpi *, cryb_mpi *, cryb_mpi *);
int mpi_cmp_abs(cryb_mpi *, cryb_mpi *);
int mpi_cmp(cryb_mpi *, cryb_mpi *);
+int mpi_eq_abs(cryb_mpi *, cryb_mpi *);
+int mpi_eq(cryb_mpi *, cryb_mpi *);
#endif
diff --git a/lib/mpi/mpi_cmp.c b/lib/mpi/mpi_cmp.c
index 55c547a..8d7a348 100644
--- a/lib/mpi/mpi_cmp.c
+++ b/lib/mpi/mpi_cmp.c
@@ -31,6 +31,7 @@
#include <stdint.h>
#include <stdlib.h>
+#include <string.h>
#include <cryb/mpi.h>
@@ -51,7 +52,7 @@ mpi_cmp_abs(cryb_mpi *X, cryb_mpi *Y)
if (X->msb < Y->msb)
return (-1);
/* no luck, compare word by word */
- for (i = X->msb / 32; i >= 0; --i) {
+ for (i = (X->msb + 31) / 32; i >= 0; --i) {
if (X->words[i] > Y->words[i])
return (1);
if (X->words[i] < Y->words[i])
@@ -79,3 +80,25 @@ mpi_cmp(cryb_mpi *X, cryb_mpi *Y)
return (mpi_cmp_abs(X, Y));
}
}
+
+/*
+ * Compare for equality
+ */
+int
+mpi_eq_abs(cryb_mpi *A, cryb_mpi *B)
+{
+
+ return (A->msb == B->msb &&
+ memcmp(A->words, B->words, (A->msb + 31) / 32) == 0);
+}
+
+/*
+ * Compare for equality
+ */
+int
+mpi_eq(cryb_mpi *A, cryb_mpi *B)
+{
+
+ return (A->neg == B->neg && A->msb != B->msb &&
+ memcmp(A->words, B->words, (A->msb + 31) / 32) == 0);
+}