diff: import bitcoin bignum class for conversions

BIGNUM is defined in OpenSSL...

Makefile.am

@@ -19,7 +19,7 @@ ccminer_SOURCES	= elist.h miner.h compat.h \
 			  compat/inttypes.h compat/stdbool.h compat/unistd.h \
 			  compat/sys/time.h compat/getopt/getopt.h \
 			  crc32.c hefty1.c \
-			  ccminer.cpp util.cpp \
+			  ccminer.cpp util.cpp bignum.cpp \
 			  api.cpp hashlog.cpp nvml.cpp stats.cpp sysinfos.cpp cuda.cpp \
 			  heavy/heavy.cu \
 			  heavy/cuda_blake512.cu heavy/cuda_blake512.h \

bignum.cpp

@@ -0,0 +1,26 @@
+/**
+ * Wrapper to OpenSSL BIGNUM used by net diff (nBits)
+ */
+
+#include <stdio.h>
+
+#include "uint256.h"
+#include "bignum.hpp"
+
+#include "miner.h" // hex2bin
+
+extern "C" double bn_convert_nbits(const uint32_t nBits)
+{
+	uint256 bn = CBigNum().SetCompact(nBits).getuint256();
+	return bn.getdouble();
+}
+
+// copy the big number to 32-bytes uchar
+extern "C" void bn_nbits_to_uchar(const uint32_t nBits, unsigned char *target)
+{
+	char buff[65];
+	uint256 bn = CBigNum().SetCompact(nBits).getuint256();
+
+	snprintf(buff, 65, "%s\n", bn.ToString().c_str()); buff[64] = '\0';
+	hex2bin(target, buff, 32);
+}