diff options
| author | Pierre Bourdon <delroth@gmail.com> | 2014-04-14 20:24:01 +0200 |
|---|---|---|
| committer | Pierre Bourdon <delroth@gmail.com> | 2014-04-14 20:24:01 +0200 |
| commit | fc71494742dbdacd20f1cbfd78f327bc0edc4690 (patch) | |
| tree | c9e50817dd5f6cc1e3eb89456b909c48efe58391 /Source/Core | |
| parent | c614a707ab1344c9adb56a5b29a805dfd982649f (diff) | |
| parent | 774a394808d6855ccd64574f5e93c1c2a3188f58 (diff) | |
Merge pull request #270 from neobrain/bitfield_fixes
Bitfield fixes
Diffstat (limited to 'Source/Core')
| -rw-r--r-- | Source/Core/Common/BitField.h | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/Source/Core/Common/BitField.h b/Source/Core/Common/BitField.h index 40e748229e..f7a0a0175c 100644 --- a/Source/Core/Common/BitField.h +++ b/Source/Core/Common/BitField.h @@ -36,6 +36,8 @@ #include <limits> #include <type_traits> +#include "Common.h" + /* * Abstract bitfield class * @@ -92,13 +94,23 @@ * * Caveats: * + * 1) * BitField provides automatic casting from and to the storage type where * appropriate. However, when using non-typesafe functions like printf, an * explicit cast must be performed on the BitField object to make sure it gets * passed correctly, e.g.: * printf("Value: %d", (s32)some_register.some_signed_fields); * + * 2) + * Not really a caveat, but potentially irritating: This class is used in some + * packed structures that do not guarantee proper alignment. Therefore we have + * to use #pragma pack here not to pack the members of the class, but instead + * to break GCC's assumption that the members of the class are aligned on + * sizeof(StorageType). + * TODO(neobrain): Confirm that this is a proper fix and not just masking + * symptoms. */ +#pragma pack(1) template<std::size_t position, std::size_t bits, typename T> struct BitField { @@ -113,13 +125,13 @@ public: // so that we can use this within unions BitField() = default; - BitField& operator=(T val) + __forceinline BitField& operator=(T val) { storage = (storage & ~GetMask()) | ((val << position) & GetMask()); return *this; } - operator T() const + __forceinline operator T() const { if (std::numeric_limits<T>::is_signed) { @@ -144,7 +156,7 @@ private: // Unsigned version of StorageType typedef typename std::make_unsigned<StorageType>::type StorageTypeU; - StorageType GetMask() const + __forceinline StorageType GetMask() const { return ((~(StorageTypeU)0) >> (8*sizeof(T) - bits)) << position; } @@ -158,3 +170,4 @@ private: static_assert(bits <= 8 * sizeof(T), "Invalid number of bits"); static_assert(bits > 0, "Invalid number of bits"); }; +#pragma pack() |