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-rw-r--r--libtommath/bn_mp_read_signed_bin.c38
1 files changed, 38 insertions, 0 deletions
diff --git a/libtommath/bn_mp_read_signed_bin.c b/libtommath/bn_mp_read_signed_bin.c
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+++ b/libtommath/bn_mp_read_signed_bin.c
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+#include <tommath.h>
+#ifdef BN_MP_READ_SIGNED_BIN_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis
+ *
+ * LibTomMath is a library that provides multiple-precision
+ * integer arithmetic as well as number theoretic functionality.
+ *
+ * The library was designed directly after the MPI library by
+ * Michael Fromberger but has been written from scratch with
+ * additional optimizations in place.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org
+ */
+
+/* read signed bin, big endian, first byte is 0==positive or 1==negative */
+int
+mp_read_signed_bin (mp_int * a, unsigned char *b, int c)
+{
+ int res;
+
+ /* read magnitude */
+ if ((res = mp_read_unsigned_bin (a, b + 1, c - 1)) != MP_OKAY) {
+ return res;
+ }
+
+ /* first byte is 0 for positive, non-zero for negative */
+ if (b[0] == 0) {
+ a->sign = MP_ZPOS;
+ } else {
+ a->sign = MP_NEG;
+ }
+
+ return MP_OKAY;
+}
+#endif