X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;ds=sidebyside;f=folly%2FBits.h;h=b22b8d57899801d9cfa76484220789d5930e00e6;hb=7d8fbeb8b9a69cee2a2f26c977ffb3f2b7b6fa92;hp=58833106ebe031a258dd2722d06338e3d1b10837;hpb=820c91a0f9cb1d5c7938a6e9394e625781919772;p=folly.git

diff --git a/folly/Bits.h b/folly/Bits.h
index 58833106..b22b8d57 100644
--- a/folly/Bits.h
+++ b/folly/Bits.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 Facebook, Inc.
+ * Copyright 2014 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -55,31 +55,31 @@
 #ifndef FOLLY_BITS_H_
 #define FOLLY_BITS_H_
 
-#include "folly/Portability.h"
-
-#ifndef __GNUC__
-#error GCC required
-#endif
-
-#ifndef __clang__
+#if !defined(__clang__) && !defined(_MSC_VER)
 #define FOLLY_INTRINSIC_CONSTEXPR constexpr
 #else
-// Unlike GCC, in Clang (as of 3.2) intrinsics aren't constexpr.
+// GCC is the only compiler with intrinsics constexpr.
 #define FOLLY_INTRINSIC_CONSTEXPR const
 #endif
 
-#ifndef FOLLY_NO_CONFIG
-#include "folly/folly-config.h"
-#endif
+#include <folly/Portability.h>
 
-#include "folly/detail/BitsDetail.h"
-#include "folly/detail/BitIteratorDetail.h"
-#include "folly/Likely.h"
+#include <folly/detail/BitsDetail.h>
+#include <folly/detail/BitIteratorDetail.h>
+#include <folly/Likely.h>
 
 #if FOLLY_HAVE_BYTESWAP_H
 # include <byteswap.h>
 #endif
 
+#ifdef _MSC_VER
+# include <intrin.h>
+# pragma intrinsic(_BitScanForward)
+# pragma intrinsic(_BitScanForward64)
+# pragma intrinsic(_BitScanReverse)
+# pragma intrinsic(_BitScanReverse64)
+#endif
+
 #include <cassert>
 #include <cinttypes>
 #include <iterator>
@@ -100,7 +100,12 @@ typename std::enable_if<
    sizeof(T) <= sizeof(unsigned int)),
   unsigned int>::type
   findFirstSet(T x) {
+#ifdef _MSC_VER
+  unsigned long index;
+  return _BitScanForward(&index, x) ? index : 0;
+#else
   return __builtin_ffs(x);
+#endif
 }
 
 template <class T>
@@ -112,7 +117,12 @@ typename std::enable_if<
    sizeof(T) <= sizeof(unsigned long)),
   unsigned int>::type
   findFirstSet(T x) {
+#ifdef _MSC_VER
+  unsigned long index;
+  return _BitScanForward(&index, x) ? index : 0;
+#else
   return __builtin_ffsl(x);
+#endif
 }
 
 template <class T>
@@ -124,7 +134,12 @@ typename std::enable_if<
    sizeof(T) <= sizeof(unsigned long long)),
   unsigned int>::type
   findFirstSet(T x) {
+#ifdef _MSC_VER
+  unsigned long index;
+  return _BitScanForward64(&index, x) ? index : 0;
+#else
   return __builtin_ffsll(x);
+#endif
 }
 
 template <class T>
@@ -149,7 +164,18 @@ typename std::enable_if<
    sizeof(T) <= sizeof(unsigned int)),
   unsigned int>::type
   findLastSet(T x) {
+#ifdef _MSC_VER
+  unsigned long index;
+  int clz;
+  if (_BitScanReverse(&index, x)) {
+    clz = static_cast<int>(31 - index);
+  } else {
+    clz = 32;
+  }
+  return x ? 8 * sizeof(unsigned int) - clz : 0;
+#else
   return x ? 8 * sizeof(unsigned int) - __builtin_clz(x) : 0;
+#endif
 }
 
 template <class T>
@@ -161,7 +187,18 @@ typename std::enable_if<
    sizeof(T) <= sizeof(unsigned long)),
   unsigned int>::type
   findLastSet(T x) {
+#ifdef _MSC_VER
+  unsigned long index;
+  int clz;
+  if (_BitScanReverse(&index, x)) {
+    clz = static_cast<int>(31 - index);
+  } else {
+    clz = 32;
+  }
+  return x ? 8 * sizeof(unsigned int) - clz : 0;
+#else
   return x ? 8 * sizeof(unsigned long) - __builtin_clzl(x) : 0;
+#endif
 }
 
 template <class T>
@@ -173,7 +210,18 @@ typename std::enable_if<
    sizeof(T) <= sizeof(unsigned long long)),
   unsigned int>::type
   findLastSet(T x) {
+#ifdef _MSC_VER
+  unsigned long index;
+  unsigned long long clz;
+  if (_BitScanReverse(&index, x)) {
+    clz = static_cast<unsigned long long>(63 - index);
+  } else {
+    clz = 64;
+  }
+  return x ? 8 * sizeof(unsigned long long) - clz : 0;
+#else
   return x ? 8 * sizeof(unsigned long long) - __builtin_clzll(x) : 0;
+#endif
 }
 
 template <class T>
@@ -239,6 +287,8 @@ struct EndianIntBase {
   static T swap(T x);
 };
 
+#ifndef _MSC_VER
+
 /**
  * If we have the bswap_16 macro from byteswap.h, use it; otherwise, provide our
  * own definition.
@@ -256,6 +306,8 @@ our_bswap16(Int16 x) {
 }
 #endif
 
+#endif
+
 #define FB_GEN(t, fn) \
 template<> inline t EndianIntBase<t>::swap(t x) { return fn(x); }
 
@@ -264,12 +316,21 @@ template<> inline t EndianIntBase<t>::swap(t x) { return fn(x); }
 // __builtin_bswap16 for some reason, so we have to provide our own.
 FB_GEN( int8_t,)
 FB_GEN(uint8_t,)
+#ifdef _MSC_VER
+FB_GEN( int64_t, _byteswap_uint64)
+FB_GEN(uint64_t, _byteswap_uint64)
+FB_GEN( int32_t, _byteswap_ulong)
+FB_GEN(uint32_t, _byteswap_ulong)
+FB_GEN( int16_t, _byteswap_ushort)
+FB_GEN(uint16_t, _byteswap_ushort)
+#else
 FB_GEN( int64_t, __builtin_bswap64)
 FB_GEN(uint64_t, __builtin_bswap64)
 FB_GEN( int32_t, __builtin_bswap32)
 FB_GEN(uint32_t, __builtin_bswap32)
 FB_GEN( int16_t, our_bswap16)
 FB_GEN(uint16_t, our_bswap16)
+#endif
 
 #undef FB_GEN
 
@@ -341,10 +402,12 @@ class Endian {
     return detail::EndianInt<T>::little(x);
   }
 
+#if !defined(__ANDROID__)
   FB_GEN(64)
   FB_GEN(32)
   FB_GEN(16)
   FB_GEN(8)
+#endif
 };
 
 #undef FB_GEN
@@ -524,6 +587,7 @@ template <class T, class Enable=void> struct Unaligned;
 /**
  * Representation of an unaligned value of a POD type.
  */
+FOLLY_PACK_PUSH
 template <class T>
 struct Unaligned<
     T,
@@ -531,7 +595,8 @@ struct Unaligned<
   Unaligned() = default;  // uninitialized
   /* implicit */ Unaligned(T v) : value(v) { }
   T value;
-} __attribute__((packed));
+} FOLLY_PACK_ATTR;
+FOLLY_PACK_POP
 
 /**
  * Read an unaligned value of type T and return it.