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authorRiccardo Spagni <ric@spagni.net>2015-08-24 19:34:10 +0200
committerRiccardo Spagni <ric@spagni.net>2015-10-26 18:00:53 +0200
commitbb0c161e7d4bff0e70b59c2f4267da96f34742af (patch)
tree6218bba2ad3cdaa4a8c0be027587db736a2cc946 /src/crypto/crypto_ops_builder/ref10CommentedCombined/fe_isnegative.c
parentMerge pull request #448 (diff)
downloadmonero-bb0c161e7d4bff0e70b59c2f4267da96f34742af.tar.xz
renamed folder
Diffstat (limited to 'src/crypto/crypto_ops_builder/ref10CommentedCombined/fe_isnegative.c')
-rw-r--r--src/crypto/crypto_ops_builder/ref10CommentedCombined/fe_isnegative.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/src/crypto/crypto_ops_builder/ref10CommentedCombined/fe_isnegative.c b/src/crypto/crypto_ops_builder/ref10CommentedCombined/fe_isnegative.c
new file mode 100644
index 000000000..3b2c8b8d5
--- /dev/null
+++ b/src/crypto/crypto_ops_builder/ref10CommentedCombined/fe_isnegative.c
@@ -0,0 +1,16 @@
+#include "fe.h"
+
+/*
+return 1 if f is in {1,3,5,...,q-2}
+return 0 if f is in {0,2,4,...,q-1}
+
+Preconditions:
+ |f| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc.
+*/
+
+int fe_isnegative(const fe f)
+{
+ unsigned char s[32];
+ fe_tobytes(s,f);
+ return s[0] & 1;
+}