added common/entropy_common.c
diff --git a/lib/common/entropy_common.c b/lib/common/entropy_common.c
new file mode 100644
index 0000000..b4c366e
--- /dev/null
+++ b/lib/common/entropy_common.c
@@ -0,0 +1,158 @@
+/*
+ Common functions of New Generation Entropy library
+ Copyright (C) 2016, Yann Collet.
+
+ BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are
+ met:
+
+ * Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above
+ copyright notice, this list of conditions and the following disclaimer
+ in the documentation and/or other materials provided with the
+ distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+ You can contact the author at :
+ - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy
+ - Public forum : https://groups.google.com/forum/#!forum/lz4c
+*************************************************************************** */
+
+/* *************************************
+* Dependencies
+***************************************/
+#include <stdlib.h>
+#include "mem.h"
+#include "fse_static.h" /* FSE_MIN_TABLELOG */
+#include "error_private.h"
+#include "fse.h" /* declaration of FSE_isError, FSE_getErrorName */
+#include "huf.h" /* declaration of HUF_isError, HUF_getErrorName */
+
+
+
+/*-****************************************
+* FSE Error Management
+******************************************/
+unsigned FSE_isError(size_t code) { return ERR_isError(code); }
+
+const char* FSE_getErrorName(size_t code) { return ERR_getErrorName(code); }
+
+
+/* **************************************************************
+* HUF Error Management
+****************************************************************/
+unsigned HUF_isError(size_t code) { return ERR_isError(code); }
+
+const char* HUF_getErrorName(size_t code) { return ERR_getErrorName(code); }
+
+
+/*-**************************************************************
+* FSE NCount encoding-decoding
+****************************************************************/
+static short FSE_abs(short a) { return a<0 ? -a : a; }
+
+size_t FSE_readNCount (short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
+ const void* headerBuffer, size_t hbSize)
+{
+ const BYTE* const istart = (const BYTE*) headerBuffer;
+ const BYTE* const iend = istart + hbSize;
+ const BYTE* ip = istart;
+ int nbBits;
+ int remaining;
+ int threshold;
+ U32 bitStream;
+ int bitCount;
+ unsigned charnum = 0;
+ int previous0 = 0;
+
+ if (hbSize < 4) return ERROR(srcSize_wrong);
+ bitStream = MEM_readLE32(ip);
+ nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */
+ if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge);
+ bitStream >>= 4;
+ bitCount = 4;
+ *tableLogPtr = nbBits;
+ remaining = (1<<nbBits)+1;
+ threshold = 1<<nbBits;
+ nbBits++;
+
+ while ((remaining>1) && (charnum<=*maxSVPtr)) {
+ if (previous0) {
+ unsigned n0 = charnum;
+ while ((bitStream & 0xFFFF) == 0xFFFF) {
+ n0+=24;
+ if (ip < iend-5) {
+ ip+=2;
+ bitStream = MEM_readLE32(ip) >> bitCount;
+ } else {
+ bitStream >>= 16;
+ bitCount+=16;
+ } }
+ while ((bitStream & 3) == 3) {
+ n0+=3;
+ bitStream>>=2;
+ bitCount+=2;
+ }
+ n0 += bitStream & 3;
+ bitCount += 2;
+ if (n0 > *maxSVPtr) return ERROR(maxSymbolValue_tooSmall);
+ while (charnum < n0) normalizedCounter[charnum++] = 0;
+ if ((ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
+ ip += bitCount>>3;
+ bitCount &= 7;
+ bitStream = MEM_readLE32(ip) >> bitCount;
+ }
+ else
+ bitStream >>= 2;
+ }
+ { short const max = (short)((2*threshold-1)-remaining);
+ short count;
+
+ if ((bitStream & (threshold-1)) < (U32)max) {
+ count = (short)(bitStream & (threshold-1));
+ bitCount += nbBits-1;
+ } else {
+ count = (short)(bitStream & (2*threshold-1));
+ if (count >= threshold) count -= max;
+ bitCount += nbBits;
+ }
+
+ count--; /* extra accuracy */
+ remaining -= FSE_abs(count);
+ normalizedCounter[charnum++] = count;
+ previous0 = !count;
+ while (remaining < threshold) {
+ nbBits--;
+ threshold >>= 1;
+ }
+
+ if ((ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
+ ip += bitCount>>3;
+ bitCount &= 7;
+ } else {
+ bitCount -= (int)(8 * (iend - 4 - ip));
+ ip = iend - 4;
+ }
+ bitStream = MEM_readLE32(ip) >> (bitCount & 31);
+ } } /* while ((remaining>1) && (charnum<=*maxSVPtr)) */
+ if (remaining != 1) return ERROR(GENERIC);
+ *maxSVPtr = charnum-1;
+
+ ip += (bitCount+7)>>3;
+ if ((size_t)(ip-istart) > hbSize) return ERROR(srcSize_wrong);
+ return ip-istart;
+}