diff --git a/contrib/pzstd/test/PzstdTest.cpp b/contrib/pzstd/test/PzstdTest.cpp
index 75453f5f6f3..3249f860af0 100644
--- a/contrib/pzstd/test/PzstdTest.cpp
+++ b/contrib/pzstd/test/PzstdTest.cpp
@@ -7,9 +7,7 @@
  * in the COPYING file in the root directory of this source tree).
  */
 #include "Pzstd.h"
-extern "C" {
 #include "datagen.h"
-}
 #include "test/RoundTrip.h"
 #include "utils/ScopeGuard.h"
 
diff --git a/contrib/pzstd/test/RoundTripTest.cpp b/contrib/pzstd/test/RoundTripTest.cpp
index c37646d1c44..27c5028e880 100644
--- a/contrib/pzstd/test/RoundTripTest.cpp
+++ b/contrib/pzstd/test/RoundTripTest.cpp
@@ -6,9 +6,7 @@
  * LICENSE file in the root directory of this source tree) and the GPLv2 (found
  * in the COPYING file in the root directory of this source tree).
  */
-extern "C" {
 #include "datagen.h"
-}
 #include "Options.h"
 #include "test/RoundTrip.h"
 #include "utils/ScopeGuard.h"
diff --git a/contrib/seekable_format/zstd_seekable.h b/contrib/seekable_format/zstd_seekable.h
index a0e5e3573d0..b1f83d0e0a1 100644
--- a/contrib/seekable_format/zstd_seekable.h
+++ b/contrib/seekable_format/zstd_seekable.h
@@ -1,13 +1,13 @@
 #ifndef SEEKABLE_H
 #define SEEKABLE_H
 
+#include <stdio.h>
+#include "zstd.h"   /* ZSTDLIB_API */
+
 #if defined (__cplusplus)
 extern "C" {
 #endif
 
-#include <stdio.h>
-#include "zstd.h"   /* ZSTDLIB_API */
-
 
 #define ZSTD_seekTableFooterSize 9
 
diff --git a/lib/common/bitstream.h b/lib/common/bitstream.h
index 676044989c9..bcfa09b8904 100644
--- a/lib/common/bitstream.h
+++ b/lib/common/bitstream.h
@@ -14,9 +14,6 @@
 #ifndef BITSTREAM_H_MODULE
 #define BITSTREAM_H_MODULE
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
 /*
 *  This API consists of small unitary functions, which must be inlined for best performance.
 *  Since link-time-optimization is not available for all compilers,
@@ -32,7 +29,6 @@ extern "C" {
 #include "error_private.h"  /* error codes and messages */
 #include "bits.h"           /* ZSTD_highbit32 */
 
-
 /*=========================================
 *  Target specific
 =========================================*/
@@ -450,8 +446,4 @@ MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* DStream)
     return ((DStream->ptr == DStream->start) && (DStream->bitsConsumed == sizeof(DStream->bitContainer)*8));
 }
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* BITSTREAM_H_MODULE */
diff --git a/lib/common/debug.h b/lib/common/debug.h
index a16b69e5743..4b60ddf7f51 100644
--- a/lib/common/debug.h
+++ b/lib/common/debug.h
@@ -32,10 +32,6 @@
 #ifndef DEBUG_H_12987983217
 #define DEBUG_H_12987983217
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 
 /* static assert is triggered at compile time, leaving no runtime artefact.
  * static assert only works with compile-time constants.
@@ -108,9 +104,4 @@ extern int g_debuglevel; /* the variable is only declared,
 #  define DEBUGLOG(l, ...) do { } while (0)    /* disabled */
 #endif
 
-
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* DEBUG_H_12987983217 */
diff --git a/lib/common/error_private.h b/lib/common/error_private.h
index 0156010c745..9dcc8595123 100644
--- a/lib/common/error_private.h
+++ b/lib/common/error_private.h
@@ -13,11 +13,6 @@
 #ifndef ERROR_H_MODULE
 #define ERROR_H_MODULE
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
-
 /* ****************************************
 *  Dependencies
 ******************************************/
@@ -26,7 +21,6 @@ extern "C" {
 #include "debug.h"
 #include "zstd_deps.h"       /* size_t */
 
-
 /* ****************************************
 *  Compiler-specific
 ******************************************/
@@ -161,8 +155,4 @@ void _force_has_format_string(const char *format, ...) {
         }                                                                          \
     } while(0)
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* ERROR_H_MODULE */
diff --git a/lib/common/fse.h b/lib/common/fse.h
index 2ae128e60db..b1940d9426a 100644
--- a/lib/common/fse.h
+++ b/lib/common/fse.h
@@ -11,11 +11,6 @@
  * in the COPYING file in the root directory of this source tree).
  * You may select, at your option, one of the above-listed licenses.
 ****************************************************************** */
-
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #ifndef FSE_H
 #define FSE_H
 
@@ -25,7 +20,6 @@ extern "C" {
 ******************************************/
 #include "zstd_deps.h"    /* size_t, ptrdiff_t */
 
-
 /*-*****************************************
 *  FSE_PUBLIC_API : control library symbols visibility
 ******************************************/
@@ -232,11 +226,8 @@ If there is an error, the function will return an error code, which can be teste
 
 #if defined(FSE_STATIC_LINKING_ONLY) && !defined(FSE_H_FSE_STATIC_LINKING_ONLY)
 #define FSE_H_FSE_STATIC_LINKING_ONLY
-
-/* *** Dependency *** */
 #include "bitstream.h"
 
-
 /* *****************************************
 *  Static allocation
 *******************************************/
@@ -631,10 +622,4 @@ MEM_STATIC unsigned FSE_endOfDState(const FSE_DState_t* DStatePtr)
 
 #define FSE_TABLESTEP(tableSize) (((tableSize)>>1) + ((tableSize)>>3) + 3)
 
-
 #endif /* FSE_STATIC_LINKING_ONLY */
-
-
-#if defined (__cplusplus)
-}
-#endif
diff --git a/lib/common/huf.h b/lib/common/huf.h
index 99bf85d6f4e..4b142c4f996 100644
--- a/lib/common/huf.h
+++ b/lib/common/huf.h
@@ -12,10 +12,6 @@
  * You may select, at your option, one of the above-listed licenses.
 ****************************************************************** */
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #ifndef HUF_H_298734234
 #define HUF_H_298734234
 
@@ -25,7 +21,6 @@ extern "C" {
 #define FSE_STATIC_LINKING_ONLY
 #include "fse.h"
 
-
 /* ***   Tool functions *** */
 #define HUF_BLOCKSIZE_MAX (128 * 1024)   /**< maximum input size for a single block compressed with HUF_compress */
 size_t HUF_compressBound(size_t size);   /**< maximum compressed size (worst case) */
@@ -280,7 +275,3 @@ size_t HUF_readDTableX2_wksp(HUF_DTable* DTable, const void* src, size_t srcSize
 #endif
 
 #endif   /* HUF_H_298734234 */
-
-#if defined (__cplusplus)
-}
-#endif
diff --git a/lib/common/mem.h b/lib/common/mem.h
index a02141c9d49..ca756e23711 100644
--- a/lib/common/mem.h
+++ b/lib/common/mem.h
@@ -11,10 +11,6 @@
 #ifndef MEM_H_MODULE
 #define MEM_H_MODULE
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 /*-****************************************
 *  Dependencies
 ******************************************/
@@ -76,7 +72,6 @@ extern "C" {
   typedef   signed long long  S64;
 #endif
 
-
 /*-**************************************************************
 *  Memory I/O API
 *****************************************************************/
@@ -424,9 +419,4 @@ MEM_STATIC void MEM_writeBEST(void* memPtr, size_t val)
 /* code only tested on 32 and 64 bits systems */
 MEM_STATIC void MEM_check(void) { DEBUG_STATIC_ASSERT((sizeof(size_t)==4) || (sizeof(size_t)==8)); }
 
-
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* MEM_H_MODULE */
diff --git a/lib/common/pool.h b/lib/common/pool.h
index cca4de73a83..f39b7f1eb99 100644
--- a/lib/common/pool.h
+++ b/lib/common/pool.h
@@ -11,10 +11,6 @@
 #ifndef POOL_H
 #define POOL_H
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 
 #include "zstd_deps.h"
 #define ZSTD_STATIC_LINKING_ONLY   /* ZSTD_customMem */
@@ -82,9 +78,4 @@ void POOL_add(POOL_ctx* ctx, POOL_function function, void* opaque);
  */
 int POOL_tryAdd(POOL_ctx* ctx, POOL_function function, void* opaque);
 
-
-#if defined (__cplusplus)
-}
-#endif
-
 #endif
diff --git a/lib/common/threading.h b/lib/common/threading.h
index fb5c1c87873..e123cdf14a3 100644
--- a/lib/common/threading.h
+++ b/lib/common/threading.h
@@ -16,10 +16,6 @@
 
 #include "debug.h"
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #if defined(ZSTD_MULTITHREAD) && defined(_WIN32)
 
 /**
@@ -72,7 +68,6 @@ int ZSTD_pthread_join(ZSTD_pthread_t thread);
  * add here more wrappers as required
  */
 
-
 #elif defined(ZSTD_MULTITHREAD)    /* posix assumed ; need a better detection method */
 /* ===   POSIX Systems   === */
 #  include <pthread.h>
@@ -143,8 +138,5 @@ typedef int ZSTD_pthread_cond_t;
 
 #endif /* ZSTD_MULTITHREAD */
 
-#if defined (__cplusplus)
-}
-#endif
 
 #endif /* THREADING_H_938743 */
diff --git a/lib/common/xxhash.h b/lib/common/xxhash.h
index e59e44267c1..68ec6b29fd1 100644
--- a/lib/common/xxhash.h
+++ b/lib/common/xxhash.h
@@ -227,10 +227,6 @@
  * xxHash prototypes and implementation
  */
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 /* ****************************
  *  INLINE mode
  ******************************/
@@ -537,6 +533,9 @@ extern "C" {
 /*! @brief Version number, encoded as two digits each */
 #define XXH_VERSION_NUMBER  (XXH_VERSION_MAJOR *100*100 + XXH_VERSION_MINOR *100 + XXH_VERSION_RELEASE)
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
 /*!
  * @brief Obtains the xxHash version.
  *
@@ -547,6 +546,9 @@ extern "C" {
  */
 XXH_PUBLIC_API XXH_CONSTF unsigned XXH_versionNumber (void);
 
+#if defined (__cplusplus)
+}
+#endif
 
 /* ****************************
 *  Common basic types
@@ -593,6 +595,10 @@ typedef uint32_t XXH32_hash_t;
 #   endif
 #endif
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
 /*!
  * @}
  *
@@ -821,6 +827,9 @@ XXH_PUBLIC_API XXH_PUREF XXH32_hash_t XXH32_hashFromCanonical(const XXH32_canoni
 #endif
 /*! @endcond */
 
+#if defined (__cplusplus)
+} /* end of extern "C" */
+#endif
 
 /*!
  * @}
@@ -859,6 +868,9 @@ typedef uint64_t XXH64_hash_t;
 #  endif
 #endif
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
 /*!
  * @}
  *
@@ -1562,6 +1574,11 @@ XXH_PUBLIC_API XXH_PUREF XXH128_hash_t XXH128_hashFromCanonical(XXH_NOESCAPE con
 
 
 #endif  /* !XXH_NO_XXH3 */
+
+#if defined (__cplusplus)
+} /* extern "C" */
+#endif
+
 #endif  /* XXH_NO_LONG_LONG */
 
 /*!
@@ -1748,6 +1765,10 @@ struct XXH3_state_s {
     } while(0)
 
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
 /*!
  * @brief Calculates the 128-bit hash of @p data using XXH3.
  *
@@ -1963,8 +1984,13 @@ XXH3_128bits_reset_withSecretandSeed(XXH_NOESCAPE XXH3_state_t* statePtr,
                                      XXH64_hash_t seed64);
 #endif /* !XXH_NO_STREAM */
 
+#if defined (__cplusplus)
+} /* extern "C" */
+#endif
+
 #endif  /* !XXH_NO_XXH3 */
 #endif  /* XXH_NO_LONG_LONG */
+
 #if defined(XXH_INLINE_ALL) || defined(XXH_PRIVATE_API)
 #  define XXH_IMPLEMENTATION
 #endif
@@ -2263,10 +2289,12 @@ XXH3_128bits_reset_withSecretandSeed(XXH_NOESCAPE XXH3_state_t* statePtr,
  * @{
  */
 
-
 /* *************************************
 *  Includes & Memory related functions
 ***************************************/
+#include <string.h>   /* memcmp, memcpy */
+#include <limits.h>   /* ULLONG_MAX */
+
 #if defined(XXH_NO_STREAM)
 /* nothing */
 #elif defined(XXH_NO_STDLIB)
@@ -2280,9 +2308,17 @@ XXH3_128bits_reset_withSecretandSeed(XXH_NOESCAPE XXH3_state_t* statePtr,
  * without access to dynamic allocation.
  */
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
 static XXH_CONSTF void* XXH_malloc(size_t s) { (void)s; return NULL; }
 static void XXH_free(void* p) { (void)p; }
 
+#if defined (__cplusplus)
+} /* extern "C" */
+#endif
+
 #else
 
 /*
@@ -2291,6 +2327,9 @@ static void XXH_free(void* p) { (void)p; }
  */
 #include <stdlib.h>
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
 /*!
  * @internal
  * @brief Modify this function to use a different routine than malloc().
@@ -2303,10 +2342,15 @@ static XXH_MALLOCF void* XXH_malloc(size_t s) { return malloc(s); }
  */
 static void XXH_free(void* p) { free(p); }
 
-#endif  /* XXH_NO_STDLIB */
+#if defined (__cplusplus)
+} /* extern "C" */
+#endif
 
-#include <string.h>
+#endif  /* XXH_NO_STDLIB */
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
 /*!
  * @internal
  * @brief Modify this function to use a different routine than memcpy().
@@ -2316,8 +2360,9 @@ static void* XXH_memcpy(void* dest, const void* src, size_t size)
     return memcpy(dest,src,size);
 }
 
-#include <limits.h>   /* ULLONG_MAX */
-
+#if defined (__cplusplus)
+} /* extern "C" */
+#endif
 
 /* *************************************
 *  Compiler Specific Options
@@ -2452,6 +2497,10 @@ typedef XXH32_hash_t xxh_u32;
 #  define U32  xxh_u32
 #endif
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
 /* ***   Memory access   *** */
 
 /*!
@@ -3608,6 +3657,10 @@ XXH_PUBLIC_API XXH64_hash_t XXH64_hashFromCanonical(XXH_NOESCAPE const XXH64_can
     return XXH_readBE64(src);
 }
 
+#if defined (__cplusplus)
+}
+#endif
+
 #ifndef XXH_NO_XXH3
 
 /* *********************************************************************
@@ -3928,6 +3981,10 @@ enum XXH_VECTOR_TYPE /* fake enum */ {
 #  pragma GCC optimize("-O2")
 #endif
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
 #if XXH_VECTOR == XXH_NEON
 
 /*
@@ -4050,6 +4107,10 @@ XXH_vmlal_high_u32(uint64x2_t acc, uint32x4_t lhs, uint32x4_t rhs)
 # endif
 #endif  /* XXH_VECTOR == XXH_NEON */
 
+#if defined (__cplusplus)
+} /* extern "C" */
+#endif
+
 /*
  * VSX and Z Vector helpers.
  *
@@ -4111,6 +4172,9 @@ typedef xxh_u64x2 xxh_aliasing_u64x2 XXH_ALIASING;
 #  if defined(__POWER9_VECTOR__) || (defined(__clang__) && defined(__s390x__))
 #    define XXH_vec_revb vec_revb
 #  else
+#if defined (__cplusplus)
+extern "C" {
+#endif
 /*!
  * A polyfill for POWER9's vec_revb().
  */
@@ -4120,9 +4184,15 @@ XXH_FORCE_INLINE xxh_u64x2 XXH_vec_revb(xxh_u64x2 val)
                                   0x0F, 0x0E, 0x0D, 0x0C, 0x0B, 0x0A, 0x09, 0x08 };
     return vec_perm(val, val, vByteSwap);
 }
+#if defined (__cplusplus)
+} /* extern "C" */
+#endif
 #  endif
 # endif /* XXH_VSX_BE */
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
 /*!
  * Performs an unaligned vector load and byte swaps it on big endian.
  */
@@ -4167,6 +4237,11 @@ XXH_FORCE_INLINE xxh_u64x2 XXH_vec_mule(xxh_u32x4 a, xxh_u32x4 b)
     return result;
 }
 # endif /* XXH_vec_mulo, XXH_vec_mule */
+
+#if defined (__cplusplus)
+} /* extern "C" */
+#endif
+
 #endif /* XXH_VECTOR == XXH_VSX */
 
 #if XXH_VECTOR == XXH_SVE
@@ -4200,7 +4275,9 @@ do { \
 #  endif
 #endif  /* XXH_NO_PREFETCH */
 
-
+#if defined (__cplusplus)
+extern "C" {
+#endif
 /* ==========================================
  * XXH3 default settings
  * ========================================== */
@@ -6877,8 +6954,6 @@ XXH_PUBLIC_API XXH128_hash_t XXH3_128bits_digest (XXH_NOESCAPE const XXH3_state_
 #endif /* !XXH_NO_STREAM */
 /* 128-bit utility functions */
 
-#include <string.h>   /* memcmp, memcpy */
-
 /* return : 1 is equal, 0 if different */
 /*! @ingroup XXH3_family */
 XXH_PUBLIC_API int XXH128_isEqual(XXH128_hash_t h1, XXH128_hash_t h2)
@@ -7005,16 +7080,15 @@ XXH3_generateSecret_fromSeed(XXH_NOESCAPE void* secretBuffer, XXH64_hash_t seed)
 #  pragma GCC pop_options
 #endif
 
-#endif  /* XXH_NO_LONG_LONG */
 
+#if defined (__cplusplus)
+} /* extern "C" */
+#endif
+
+#endif  /* XXH_NO_LONG_LONG */
 #endif  /* XXH_NO_XXH3 */
 
 /*!
  * @}
  */
 #endif  /* XXH_IMPLEMENTATION */
-
-
-#if defined (__cplusplus)
-} /* extern "C" */
-#endif
diff --git a/lib/common/zstd_internal.h b/lib/common/zstd_internal.h
index b67ca863384..2789a359122 100644
--- a/lib/common/zstd_internal.h
+++ b/lib/common/zstd_internal.h
@@ -39,10 +39,6 @@
 #  define ZSTD_TRACE 0
 #endif
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 /* ---- static assert (debug) --- */
 #define ZSTD_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c)
 #define ZSTD_isError ERR_isError   /* for inlining */
@@ -325,8 +321,4 @@ MEM_STATIC int ZSTD_cpuSupportsBmi2(void)
     return ZSTD_cpuid_bmi1(cpuid) && ZSTD_cpuid_bmi2(cpuid);
 }
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif   /* ZSTD_CCOMMON_H_MODULE */
diff --git a/lib/common/zstd_trace.h b/lib/common/zstd_trace.h
index d33edf35db6..d8eec100758 100644
--- a/lib/common/zstd_trace.h
+++ b/lib/common/zstd_trace.h
@@ -11,10 +11,6 @@
 #ifndef ZSTD_TRACE_H
 #define ZSTD_TRACE_H
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #include <stddef.h>
 
 /* weak symbol support
@@ -157,8 +153,4 @@ ZSTD_WEAK_ATTR void ZSTD_trace_decompress_end(
 
 #endif /* ZSTD_TRACE */
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* ZSTD_TRACE_H */
diff --git a/lib/compress/zstd_compress_internal.h b/lib/compress/zstd_compress_internal.h
index 2d4ecc89f18..2be67a1240a 100644
--- a/lib/compress/zstd_compress_internal.h
+++ b/lib/compress/zstd_compress_internal.h
@@ -26,10 +26,6 @@
 #include "../common/bits.h" /* ZSTD_highbit32, ZSTD_NbCommonBytes */
 #include "zstd_preSplit.h" /* ZSTD_SLIPBLOCK_WORKSPACESIZE */
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 /*-*************************************
 *  Constants
 ***************************************/
@@ -1503,10 +1499,6 @@ MEM_STATIC int ZSTD_comparePackedTags(size_t packedTag1, size_t packedTag2) {
     return tag1 == tag2;
 }
 
-#if defined (__cplusplus)
-}
-#endif
-
 /* ===============================================================
  * Shared internal declarations
  * These prototypes may be called from sources not in lib/compress
diff --git a/lib/compress/zstd_cwksp.h b/lib/compress/zstd_cwksp.h
index aa4c3e49e08..77518002d00 100644
--- a/lib/compress/zstd_cwksp.h
+++ b/lib/compress/zstd_cwksp.h
@@ -19,10 +19,6 @@
 #include "../common/portability_macros.h"
 #include "../common/compiler.h" /* ZS2_isPower2 */
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 /*-*************************************
 *  Constants
 ***************************************/
@@ -766,8 +762,4 @@ MEM_STATIC void ZSTD_cwksp_bump_oversized_duration(
     }
 }
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* ZSTD_CWKSP_H */
diff --git a/lib/compress/zstd_double_fast.h b/lib/compress/zstd_double_fast.h
index c58697ad243..cd562fea8ef 100644
--- a/lib/compress/zstd_double_fast.h
+++ b/lib/compress/zstd_double_fast.h
@@ -11,10 +11,6 @@
 #ifndef ZSTD_DOUBLE_FAST_H
 #define ZSTD_DOUBLE_FAST_H
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #include "../common/mem.h"      /* U32 */
 #include "zstd_compress_internal.h"     /* ZSTD_CCtx, size_t */
 
@@ -43,8 +39,4 @@ size_t ZSTD_compressBlock_doubleFast_extDict(
 #define ZSTD_COMPRESSBLOCK_DOUBLEFAST_EXTDICT NULL
 #endif /* ZSTD_EXCLUDE_DFAST_BLOCK_COMPRESSOR */
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* ZSTD_DOUBLE_FAST_H */
diff --git a/lib/compress/zstd_fast.h b/lib/compress/zstd_fast.h
index f7fbf4f683c..216821ac33b 100644
--- a/lib/compress/zstd_fast.h
+++ b/lib/compress/zstd_fast.h
@@ -11,10 +11,6 @@
 #ifndef ZSTD_FAST_H
 #define ZSTD_FAST_H
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #include "../common/mem.h"      /* U32 */
 #include "zstd_compress_internal.h"
 
@@ -31,8 +27,4 @@ size_t ZSTD_compressBlock_fast_extDict(
         ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
         void const* src, size_t srcSize);
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* ZSTD_FAST_H */
diff --git a/lib/compress/zstd_lazy.h b/lib/compress/zstd_lazy.h
index 6da51e4ecff..bd8dc49e64c 100644
--- a/lib/compress/zstd_lazy.h
+++ b/lib/compress/zstd_lazy.h
@@ -11,10 +11,6 @@
 #ifndef ZSTD_LAZY_H
 #define ZSTD_LAZY_H
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #include "zstd_compress_internal.h"
 
 /**
@@ -194,9 +190,4 @@ size_t ZSTD_compressBlock_btlazy2_extDict(
 #define ZSTD_COMPRESSBLOCK_BTLAZY2_EXTDICT NULL
 #endif
 
-
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* ZSTD_LAZY_H */
diff --git a/lib/compress/zstd_ldm.h b/lib/compress/zstd_ldm.h
index 8efa7c4f0eb..42736231aa8 100644
--- a/lib/compress/zstd_ldm.h
+++ b/lib/compress/zstd_ldm.h
@@ -11,10 +11,6 @@
 #ifndef ZSTD_LDM_H
 #define ZSTD_LDM_H
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #include "zstd_compress_internal.h"   /* ldmParams_t, U32 */
 #include "../zstd.h"   /* ZSTD_CCtx, size_t */
 
@@ -110,8 +106,4 @@ size_t ZSTD_ldm_getMaxNbSeq(ldmParams_t params, size_t maxChunkSize);
 void ZSTD_ldm_adjustParameters(ldmParams_t* params,
                                ZSTD_compressionParameters const* cParams);
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* ZSTD_FAST_H */
diff --git a/lib/compress/zstd_opt.h b/lib/compress/zstd_opt.h
index 247c9ee6572..756c7b1d0c5 100644
--- a/lib/compress/zstd_opt.h
+++ b/lib/compress/zstd_opt.h
@@ -11,10 +11,6 @@
 #ifndef ZSTD_OPT_H
 #define ZSTD_OPT_H
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #include "zstd_compress_internal.h"
 
 #if !defined(ZSTD_EXCLUDE_BTLAZY2_BLOCK_COMPRESSOR) \
@@ -73,8 +69,4 @@ size_t ZSTD_compressBlock_btultra2(
 #define ZSTD_COMPRESSBLOCK_BTULTRA2 NULL
 #endif
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* ZSTD_OPT_H */
diff --git a/lib/compress/zstd_preSplit.h b/lib/compress/zstd_preSplit.h
index d606a52b59e..b89a200dccd 100644
--- a/lib/compress/zstd_preSplit.h
+++ b/lib/compress/zstd_preSplit.h
@@ -13,10 +13,6 @@
 
 #include <stddef.h>  /* size_t */
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #define ZSTD_SLIPBLOCK_WORKSPACESIZE 8208
 
 /* ZSTD_splitBlock():
@@ -34,8 +30,4 @@ size_t ZSTD_splitBlock(const void* blockStart, size_t blockSize,
                     int level,
                     void* workspace, size_t wkspSize);
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* ZSTD_PRESPLIT_H */
diff --git a/lib/compress/zstdmt_compress.h b/lib/compress/zstdmt_compress.h
index ed4dc0e99df..91b489b9cb4 100644
--- a/lib/compress/zstdmt_compress.h
+++ b/lib/compress/zstdmt_compress.h
@@ -11,10 +11,10 @@
  #ifndef ZSTDMT_COMPRESS_H
  #define ZSTDMT_COMPRESS_H
 
- #if defined (__cplusplus)
- extern "C" {
- #endif
-
+/* ===   Dependencies   === */
+#include "../common/zstd_deps.h"   /* size_t */
+#define ZSTD_STATIC_LINKING_ONLY   /* ZSTD_parameters */
+#include "../zstd.h"            /* ZSTD_inBuffer, ZSTD_outBuffer, ZSTDLIB_API */
 
 /* Note : This is an internal API.
  *        These APIs used to be exposed with ZSTDLIB_API,
@@ -25,12 +25,6 @@
  *        otherwise ZSTDMT_createCCtx*() will fail.
  */
 
-/* ===   Dependencies   === */
-#include "../common/zstd_deps.h"   /* size_t */
-#define ZSTD_STATIC_LINKING_ONLY   /* ZSTD_parameters */
-#include "../zstd.h"            /* ZSTD_inBuffer, ZSTD_outBuffer, ZSTDLIB_API */
-
-
 /* ===   Constants   === */
 #ifndef ZSTDMT_NBWORKERS_MAX /* a different value can be selected at compile time */
 #  define ZSTDMT_NBWORKERS_MAX ((sizeof(void*)==4) /*32-bit*/ ? 64 : 256)
@@ -105,9 +99,4 @@ void ZSTDMT_updateCParams_whileCompressing(ZSTDMT_CCtx* mtctx, const ZSTD_CCtx_p
  */
 ZSTD_frameProgression ZSTDMT_getFrameProgression(ZSTDMT_CCtx* mtctx);
 
-
-#if defined (__cplusplus)
-}
-#endif
-
 #endif   /* ZSTDMT_COMPRESS_H */
diff --git a/lib/dictBuilder/divsufsort.h b/lib/dictBuilder/divsufsort.h
index 5440994af15..3ed2b287ab1 100644
--- a/lib/dictBuilder/divsufsort.h
+++ b/lib/dictBuilder/divsufsort.h
@@ -27,11 +27,6 @@
 #ifndef _DIVSUFSORT_H
 #define _DIVSUFSORT_H 1
 
-#ifdef __cplusplus
-extern "C" {
-#endif /* __cplusplus */
-
-
 /*- Prototypes -*/
 
 /**
@@ -59,9 +54,4 @@ divsufsort(const unsigned char *T, int *SA, int n, int openMP);
 int
 divbwt(const unsigned char *T, unsigned char *U, int *A, int n, unsigned char * num_indexes, int * indexes, int openMP);
 
-
-#ifdef __cplusplus
-} /* extern "C" */
-#endif /* __cplusplus */
-
 #endif /* _DIVSUFSORT_H */
diff --git a/lib/zdict.h b/lib/zdict.h
index bcccf750e64..599b793013b 100644
--- a/lib/zdict.h
+++ b/lib/zdict.h
@@ -8,16 +8,16 @@
  * You may select, at your option, one of the above-listed licenses.
  */
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #ifndef ZSTD_ZDICT_H
 #define ZSTD_ZDICT_H
 
+
 /*======  Dependencies  ======*/
 #include <stddef.h>  /* size_t */
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
 
 /* =====   ZDICTLIB_API : control library symbols visibility   ===== */
 #ifndef ZDICTLIB_VISIBLE
@@ -271,11 +271,19 @@ ZDICTLIB_API size_t ZDICT_getDictHeaderSize(const void* dictBuffer, size_t dictS
 ZDICTLIB_API unsigned ZDICT_isError(size_t errorCode);
 ZDICTLIB_API const char* ZDICT_getErrorName(size_t errorCode);
 
+#if defined (__cplusplus)
+}
+#endif
+
 #endif   /* ZSTD_ZDICT_H */
 
 #if defined(ZDICT_STATIC_LINKING_ONLY) && !defined(ZSTD_ZDICT_H_STATIC)
 #define ZSTD_ZDICT_H_STATIC
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
 /* This can be overridden externally to hide static symbols. */
 #ifndef ZDICTLIB_STATIC_API
 #  if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)
@@ -466,9 +474,8 @@ ZDICTLIB_STATIC_API
 size_t ZDICT_addEntropyTablesFromBuffer(void* dictBuffer, size_t dictContentSize, size_t dictBufferCapacity,
                                   const void* samplesBuffer, const size_t* samplesSizes, unsigned nbSamples);
 
-
-#endif   /* ZSTD_ZDICT_H_STATIC */
-
 #if defined (__cplusplus)
 }
 #endif
+
+#endif   /* ZSTD_ZDICT_H_STATIC */
diff --git a/lib/zstd.h b/lib/zstd.h
index 08b3b357a78..907a377d186 100644
--- a/lib/zstd.h
+++ b/lib/zstd.h
@@ -7,16 +7,22 @@
  * in the COPYING file in the root directory of this source tree).
  * You may select, at your option, one of the above-listed licenses.
  */
-#if defined (__cplusplus)
-extern "C" {
-#endif
 
 #ifndef ZSTD_H_235446
 #define ZSTD_H_235446
 
+
 /* ======   Dependencies   ======*/
 #include <stddef.h>   /* size_t */
 
+#include "zstd_errors.h" /* list of errors */
+#if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY)
+#include <limits.h>   /* INT_MAX */
+#endif /* ZSTD_STATIC_LINKING_ONLY */
+
+#if defined (__cplusplus)
+extern "C" {
+#endif
 
 /* =====   ZSTDLIB_API : control library symbols visibility   ===== */
 #ifndef ZSTDLIB_VISIBLE
@@ -245,7 +251,6 @@ ZSTDLIB_API size_t ZSTD_compressBound(size_t srcSize); /*!< maximum compressed s
 
 
 /*======  Error helper functions  ======*/
-#include "zstd_errors.h" /* list of errors */
 /* ZSTD_isError() :
  * Most ZSTD_* functions returning a size_t value can be tested for error,
  * using ZSTD_isError().
@@ -1205,6 +1210,10 @@ ZSTDLIB_API size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds);
 ZSTDLIB_API size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict);
 ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
 
+#if defined (__cplusplus)
+}
+#endif
+
 #endif  /* ZSTD_H_235446 */
 
 
@@ -1220,7 +1229,9 @@ ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
 #if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY)
 #define ZSTD_H_ZSTD_STATIC_LINKING_ONLY
 
-#include <limits.h>   /* INT_MAX */
+#if defined (__cplusplus)
+extern "C" {
+#endif
 
 /* This can be overridden externally to hide static symbols. */
 #ifndef ZSTDLIB_STATIC_API
@@ -3179,8 +3190,8 @@ ZSTDLIB_STATIC_API size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, void* dst, size_
 ZSTD_DEPRECATED("The block API is deprecated in favor of the normal compression API. See docs.")
 ZSTDLIB_STATIC_API size_t ZSTD_insertBlock    (ZSTD_DCtx* dctx, const void* blockStart, size_t blockSize);  /**< insert uncompressed block into `dctx` history. Useful for multi-blocks decompression. */
 
-#endif   /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */
-
 #if defined (__cplusplus)
 }
 #endif
+
+#endif   /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */
diff --git a/programs/benchfn.h b/programs/benchfn.h
index 1bd93d13519..3fc6e0d0455 100644
--- a/programs/benchfn.h
+++ b/programs/benchfn.h
@@ -15,17 +15,12 @@
  * or detecting and returning an error
  */
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #ifndef BENCH_FN_H_23876
 #define BENCH_FN_H_23876
 
 /* ===  Dependencies  === */
 #include <stddef.h>   /* size_t */
 
-
 /* ====  Benchmark any function, iterated on a set of blocks  ==== */
 
 /* BMK_runTime_t: valid result return type */
@@ -175,9 +170,4 @@ typedef union {
 } BMK_timedFnState_shell;
 BMK_timedFnState_t* BMK_initStatic_timedFnState(void* buffer, size_t size, unsigned total_ms, unsigned run_ms);
 
-
 #endif   /* BENCH_FN_H_23876 */
-
-#if defined (__cplusplus)
-}
-#endif
diff --git a/programs/benchzstd.h b/programs/benchzstd.h
index 6ff62d43eda..4fd0e5a8af4 100644
--- a/programs/benchzstd.h
+++ b/programs/benchzstd.h
@@ -14,10 +14,6 @@
   * and display progress result and final summary
   */
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #ifndef BENCH_ZSTD_H_3242387
 #define BENCH_ZSTD_H_3242387
 
@@ -26,7 +22,6 @@ extern "C" {
 #define ZSTD_STATIC_LINKING_ONLY   /* ZSTD_compressionParameters */
 #include "../lib/zstd.h"     /* ZSTD_compressionParameters */
 
-
 /* ===  Constants  === */
 
 #define MB_UNIT 1000000
@@ -194,7 +189,3 @@ BMK_benchOutcome_t BMK_benchMemAdvanced(const void* srcBuffer, size_t srcSize,
 
 
 #endif   /* BENCH_ZSTD_H_3242387 */
-
-#if defined (__cplusplus)
-}
-#endif
diff --git a/programs/datagen.h b/programs/datagen.h
index ca72700063f..461fb716c43 100644
--- a/programs/datagen.h
+++ b/programs/datagen.h
@@ -14,6 +14,10 @@
 
 #include <stddef.h>   /* size_t */
 
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
 void RDG_genStdout(unsigned long long size, double matchProba, double litProba, unsigned seed);
 void RDG_genBuffer(void* buffer, size_t size, double matchProba, double litProba, unsigned seed);
 /*!RDG_genBuffer
@@ -27,4 +31,8 @@ void RDG_genBuffer(void* buffer, size_t size, double matchProba, double litProba
    Same as RDG_genBuffer, but generates data into stdout
 */
 
+#if defined (__cplusplus)
+} /* extern "C" */
+#endif
+
 #endif
diff --git a/programs/fileio.h b/programs/fileio.h
index e8cb2e6abe9..cb53ef53781 100644
--- a/programs/fileio.h
+++ b/programs/fileio.h
@@ -17,11 +17,6 @@
 #define ZSTD_STATIC_LINKING_ONLY   /* ZSTD_compressionParameters */
 #include "../lib/zstd.h"           /* ZSTD_* */
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
-
 /* *************************************
 *  Special i/o constants
 **************************************/
@@ -173,9 +168,4 @@ char const* FIO_zlibVersion(void);
 char const* FIO_lz4Version(void);
 char const* FIO_lzmaVersion(void);
 
-
-#if defined (__cplusplus)
-}
-#endif
-
 #endif  /* FILEIO_H_23981798732 */
diff --git a/programs/fileio_asyncio.h b/programs/fileio_asyncio.h
index feb25a3f9e9..d4980ef5b01 100644
--- a/programs/fileio_asyncio.h
+++ b/programs/fileio_asyncio.h
@@ -22,10 +22,6 @@
 #ifndef ZSTD_FILEIO_ASYNCIO_H
 #define ZSTD_FILEIO_ASYNCIO_H
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #include "../lib/common/mem.h"     /* U32, U64 */
 #include "fileio_types.h"
 #include "platform.h"
@@ -196,8 +192,4 @@ FILE* AIO_ReadPool_getFile(const ReadPoolCtx_t *ctx);
  * Closes the current set file. Waits for all current enqueued tasks to complete and resets state. */
 int AIO_ReadPool_closeFile(ReadPoolCtx_t *ctx);
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* ZSTD_FILEIO_ASYNCIO_H */
diff --git a/programs/fileio_common.h b/programs/fileio_common.h
index 696626fe478..8aa70edea81 100644
--- a/programs/fileio_common.h
+++ b/programs/fileio_common.h
@@ -11,10 +11,6 @@
 #ifndef ZSTD_FILEIO_COMMON_H
 #define ZSTD_FILEIO_COMMON_H
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 #include "../lib/common/mem.h"     /* U32, U64 */
 #include "fileio_types.h"
 #include "platform.h"
@@ -122,7 +118,4 @@ extern UTIL_time_t g_displayClock;
 #   define LONG_TELL ftell
 #endif
 
-#if defined (__cplusplus)
-}
-#endif
 #endif /* ZSTD_FILEIO_COMMON_H */
diff --git a/programs/platform.h b/programs/platform.h
index 4d2b9490e6d..05a26a564f4 100644
--- a/programs/platform.h
+++ b/programs/platform.h
@@ -11,12 +11,6 @@
 #ifndef PLATFORM_H_MODULE
 #define PLATFORM_H_MODULE
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
-
-
 /* **************************************
 *  Compiler Options
 ****************************************/
@@ -144,10 +138,20 @@ extern "C" {
 #  include <io.h>      /* _isatty */
 #  include <windows.h> /* DeviceIoControl, HANDLE, FSCTL_SET_SPARSE */
 #  include <stdio.h>   /* FILE */
+
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
 static __inline int IS_CONSOLE(FILE* stdStream) {
     DWORD dummy;
     return _isatty(_fileno(stdStream)) && GetConsoleMode((HANDLE)_get_osfhandle(_fileno(stdStream)), &dummy);
 }
+
+#if defined (__cplusplus)
+}
+#endif
+
 #else
 #  define IS_CONSOLE(stdStream) 0
 #endif
@@ -210,9 +214,4 @@ static __inline int IS_CONSOLE(FILE* stdStream) {
 #  endif
 #endif
 
-
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* PLATFORM_H_MODULE */
diff --git a/programs/timefn.h b/programs/timefn.h
index b814ff8d8da..80f72e228a3 100644
--- a/programs/timefn.h
+++ b/programs/timefn.h
@@ -11,12 +11,6 @@
 #ifndef TIME_FN_H_MODULE_287987
 #define TIME_FN_H_MODULE_287987
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
-
-
 /*-****************************************
 *  Types
 ******************************************/
@@ -62,9 +56,4 @@ PTime UTIL_clockSpanMicro(UTIL_time_t clockStart);
 
 #define SEC_TO_MICRO ((PTime)1000000)  /* nb of microseconds in a second */
 
-
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* TIME_FN_H_MODULE_287987 */
diff --git a/programs/util.c b/programs/util.c
index 7f65f93731f..065a35855f2 100644
--- a/programs/util.c
+++ b/programs/util.c
@@ -8,11 +8,6 @@
  * You may select, at your option, one of the above-listed licenses.
  */
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
-
 /*-****************************************
 *  Dependencies
 ******************************************/
@@ -1646,7 +1641,3 @@ int UTIL_countLogicalCores(void)
 {
     return UTIL_countCores(1);
 }
-
-#if defined (__cplusplus)
-}
-#endif
diff --git a/programs/util.h b/programs/util.h
index 3a83a50ae3a..d768e766091 100644
--- a/programs/util.h
+++ b/programs/util.h
@@ -20,6 +20,9 @@
 #include <sys/types.h>    /* stat, utime */
 #include <sys/stat.h>     /* stat, chmod */
 #include "../lib/common/mem.h"          /* U64 */
+#if !(defined(_MSC_VER) || defined(__MINGW32__) || defined (__MSVCRT__))
+#include <libgen.h>
+#endif
 
 /*-************************************************************
 *  Fix fseek()'s 2GiB barrier with MSVC, macOS, *BSD, MinGW
@@ -119,7 +122,6 @@ int UTIL_requireUserConfirmation(const char* prompt, const char* abortMsg, const
 #define STRDUP(s) _strdup(s)
 #else
 #define PATH_SEP '/'
-#include <libgen.h>
 #define STRDUP(s) strdup(s)
 #endif
 
diff --git a/zlibWrapper/zstd_zlibwrapper.h b/zlibWrapper/zstd_zlibwrapper.h
index 230bf8411b0..dae6787d3ad 100644
--- a/zlibWrapper/zstd_zlibwrapper.h
+++ b/zlibWrapper/zstd_zlibwrapper.h
@@ -11,11 +11,6 @@
 #ifndef ZSTD_ZLIBWRAPPER_H
 #define ZSTD_ZLIBWRAPPER_H
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
-
 #define ZLIB_CONST
 #define Z_PREFIX
 #define ZLIB_INTERNAL   /* disables gz*64 functions but fixes zlib 1.2.4 with Z_PREFIX */
@@ -29,6 +24,11 @@ extern "C" {
     #define _Z_OF OF
 #endif
 
+
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
 /* returns a string with version of zstd library */
 const char * zstdVersion(void);