diff --git a/bitpack.h b/bitpack.h
index 94a1d27..bbc01eb 100644
--- a/bitpack.h
+++ b/bitpack.h
@@ -22,11 +22,16 @@
     - email    : powturbo [_AT_] gmail [_DOT_] com
 **/
 //     bitpack.h - "Integer Compression" Binary Packing header file
+#ifndef BITPACK_H_
+#define BITPACK_H_
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 #include <stdint.h>
+
+//********************************** Bit Packing : Pack ****************************************************************
+
 // bipackNN: Pack array with n unsigned (NN bits in[n]) values to the buffer out using nbits per value. Return value = end of compressed buffer out
 unsigned char *bitpack32(  unsigned              *__restrict in, unsigned n, unsigned char *__restrict out				   , unsigned b);
 unsigned char *bitpack16(  unsigned short        *__restrict in, unsigned n, unsigned char *__restrict out				   , unsigned b);
@@ -55,6 +60,95 @@ unsigned char *bitdpack256v32( unsigned          *__restrict in, unsigned n, uns
 unsigned char *bitd1pack256v32(unsigned          *__restrict in, unsigned n, unsigned char *__restrict out, unsigned start, unsigned b);
 unsigned char *bitzpack256v32( unsigned          *__restrict in, unsigned n, unsigned char *__restrict out, unsigned start, unsigned b);
 
+//********************************** Bit Packing : Unpack ****************************************************************
+
+// ---------------- Unpack a b-bits packed integer array --------------------------------------------------------------------------------------
+// unpack a bitpacked integer array. Return value = end of packed buffer in 
+unsigned char *bitunpack16(const unsigned char *__restrict in, unsigned n, unsigned short *__restrict out, unsigned b);
+unsigned char *bitunpack32(const unsigned char *__restrict in, unsigned n, unsigned       *__restrict out, unsigned b);
+unsigned char *bitunpack64(const unsigned char *__restrict in, unsigned n, uint64_t       *__restrict out, unsigned b);
+
+// ---------------- Direct Access to a single packed integer array entry --------------------------------------------------------------------
+  #ifndef NTURBOPFOR_DAC
+    #ifdef __AVX2__
+#include <immintrin.h>
+#define bzhi64(_u_, _b_) _bzhi_u64(_u_, _b_)
+#define bzhi32(_u_, _b_) _bzhi_u32(_u_, _b_)
+    #else
+#define bzhi64(_u_, _b_) ((_u_) & ((1ull<<(_b_))-1))
+#define bzhi32(_u_, _b_) ((_u_) & ((1u  <<(_b_))-1))
+    #endif
+
+#include "conf.h"
+
+// Get a single 32 bits value with index "idx" (or bit index b*idx) from packed integer array
+static ALWAYS_INLINE unsigned  bitgetx32(const unsigned char *__restrict in, unsigned  idx, unsigned b) { unsigned bidx = b*idx; return bzhi64( ctou64((unsigned *)in+(bidx>>5)) >> (bidx&0x1f), b ); }
+static ALWAYS_INLINE unsigned _bitgetx32(const unsigned char *__restrict in, unsigned bidx, unsigned b) {                        return bzhi64( ctou64((unsigned *)in+(bidx>>5)) >> (bidx&0x1f), b ); }
+
+// like  bitgetx32 but for 16 bits integer array
+static ALWAYS_INLINE unsigned  bitgetx16(const unsigned char *__restrict in, unsigned  idx, unsigned b) { unsigned bidx = b*idx; return bzhi32( ctou32((unsigned *)in+(bidx>>4)) >> (bidx& 0xf), b ); }
+static ALWAYS_INLINE unsigned _bitgetx16(const unsigned char *__restrict in, unsigned bidx, unsigned b) {                        return bzhi32( ctou32((unsigned *)in+(bidx>>4)) >> (bidx& 0xf), b ); }
+
+// Set a single value with index "idx" 
+static ALWAYS_INLINE void      bitsetx16(const unsigned char *__restrict in, unsigned  idx, unsigned v, unsigned b) { unsigned bidx = b*idx;  unsigned           *p = (unsigned           *)             in+(bidx>>4) ; *p = ( *p & ~(((1u  <<b)-1) << (bidx& 0xf)) ) |                     v<<(bidx& 0xf);}
+static ALWAYS_INLINE void      bitsetx32(const unsigned char *__restrict in, unsigned  idx, unsigned v, unsigned b) { unsigned bidx = b*idx;  unsigned long long *p = (unsigned long long *)((unsigned *)in+(bidx>>5)); *p = ( *p & ~(((1ull<<b)-1) << (bidx&0x1f)) ) | (unsigned long long)v<<(bidx&0x1f);}
+   #endif
+// ---------------- DFOR : integrated bitpacking, for delta packed SORTED array (Ex. DocId in inverted index) -------------------------------
+// start < out[0] < out[1] < ... < out[n-2] < out[n-1] < (1<<N)-1,    N=32,16
+// out[0] = start + in[0] + 1;  out[1] = out[0] + in[1] + 1; ... ;  out[i] = out[i-1] + in[i] +  1
+unsigned char *bitd1unpack64( const unsigned char *__restrict in, unsigned n, uint64_t       *__restrict out, uint64_t start, unsigned b);
+unsigned char *bitd1unpack32( const unsigned char *__restrict in, unsigned n, unsigned       *__restrict out, unsigned start, unsigned b);
+unsigned char *bitd1unpack16( const unsigned char *__restrict in, unsigned n, unsigned short *__restrict out, unsigned start, unsigned b);
+
+// start <= out[0] <= out[1] <= ... <= out[n-2] <= out[n-1] <= (1<<N)-1  N=32,16
+// out[0] = start + in[0];  out[1] = out[0] + in[1]; ... ;  out[i] = out[i-1] + in[i]
+unsigned char *bitdunpack32(  const unsigned char *__restrict in, unsigned n, unsigned       *__restrict out, unsigned start, unsigned b);
+unsigned char *bitdunpack16(  const unsigned char *__restrict in, unsigned n, unsigned short *__restrict out, unsigned start, unsigned b);
+unsigned char *bitdunpack64( const unsigned char *__restrict in, unsigned n, uint64_t       *__restrict out, uint64_t start, unsigned b);
+
+unsigned char *bitzunpack32(  const unsigned char *__restrict in, unsigned n, unsigned       *__restrict out, unsigned start, unsigned b);
+
+// ---------------- For : Direct Access for packed SORTED array (Ex. DocId in inverted index) --------------------------------------------
+// out[i] = start + in[i] + i + 1
+unsigned char *bitf1unpack32( const unsigned char *__restrict in, unsigned n, unsigned       *__restrict out, unsigned start, unsigned b);
+unsigned char *bitf1unpack16( const unsigned char *__restrict in, unsigned n, unsigned short *__restrict out, unsigned start, unsigned b);
+
+// out[i] = start + in[i] + i 
+unsigned char *bitfunpack32(  const unsigned char *__restrict in, unsigned n, unsigned       *__restrict out, unsigned start, unsigned b);
+unsigned char *bitfunpack16(  const unsigned char *__restrict in, unsigned n, unsigned short *__restrict out, unsigned start, unsigned b);
+
+// ---------------- SIMD : unpack a bit packed integer array -------------------------------------------------------------------------------
+// SIMD unpack a 128/256 bitpacked integer array. Return value = end of packed buffer in
+unsigned char *bitunpack128v32(  const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned b);
+unsigned char *bitzunpack128v32( const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b);
+unsigned char *bitdunpack128v32( const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b); 
+unsigned char *bitd1unpack128v32(const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b);
+
+unsigned char *bitunpack256v32(  const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned b);
+unsigned char *bitzunpack256v32( const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b);
+unsigned char *bitdunpack256v32( const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b); 
+unsigned char *bitd1unpack256v32(const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b);
+
+unsigned char *bitunpack128h32(  const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned b);
+unsigned char *bitzunpack128h32( const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b);
+unsigned char *bitdunpack128h32( const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b); 
+unsigned char *bitd1unpack128h32(const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b);
+
+// internal TurboPFor functions: masked unpack
+unsigned char *_bitunpack128v32(  const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned b, unsigned *__restrict pex, unsigned char *bb);
+unsigned char *_bitdunpack128v32( const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b, unsigned *__restrict pex, unsigned char *bb);
+unsigned char *_bitd1unpack128v32(const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b, unsigned *__restrict pex, unsigned char *bb);
+
+unsigned char *_bitunpack128h32(  const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned b, unsigned *__restrict pex, unsigned char *bb);
+unsigned char *_bitdunpack128h32( const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b, unsigned *__restrict pex, unsigned char *bb);
+unsigned char *_bitd1unpack128h32(const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b, unsigned *__restrict pex, unsigned char *bb);
+
+unsigned char *_bitunpack256v32(  const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned b, unsigned *__restrict pex, unsigned char *bb);
+unsigned char *_bitdunpack256v32( const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b, unsigned *__restrict pex, unsigned char *bb);
+unsigned char *_bitd1unpack256v32(const unsigned char *__restrict in, unsigned n, unsigned *__restrict out, unsigned start, unsigned b, unsigned *__restrict pex, unsigned char *bb);
+
 #ifdef __cplusplus
 }
 #endif
+#endif
+