| // Copyright 2013 Google Inc. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| // |
| // These are weird things we need to do to get this compiling on |
| // random systems [subset]. |
| |
| #ifndef BASE_PORT_H_ |
| #define BASE_PORT_H_ |
| |
| #include <string.h> // for memcpy() |
| #include "integral_types.h" |
| |
| namespace CLD2 { |
| |
| // Portable handling of unaligned loads, stores, and copies. |
| // On some platforms, like ARM, the copy functions can be more efficient |
| // then a load and a store. |
| |
| #if defined(ARCH_PIII) || defined(ARCH_ATHLON) || defined(ARCH_K8) || defined(_ARCH_PPC) |
| |
| // x86 and x86-64 can perform unaligned loads/stores directly; |
| // modern PowerPC hardware can also do unaligned integer loads and stores; |
| // but note: the FPU still sends unaligned loads and stores to a trap handler! |
| |
| #define UNALIGNED_LOAD16(_p) (*reinterpret_cast<const uint16 *>(_p)) |
| #define UNALIGNED_LOAD32(_p) (*reinterpret_cast<const uint32 *>(_p)) |
| #define UNALIGNED_LOAD64(_p) (*reinterpret_cast<const uint64 *>(_p)) |
| |
| #define UNALIGNED_STORE16(_p, _val) (*reinterpret_cast<uint16 *>(_p) = (_val)) |
| #define UNALIGNED_STORE32(_p, _val) (*reinterpret_cast<uint32 *>(_p) = (_val)) |
| #define UNALIGNED_STORE64(_p, _val) (*reinterpret_cast<uint64 *>(_p) = (_val)) |
| |
| #elif defined(__arm__) && \ |
| !defined(__ARM_ARCH_5__) && \ |
| !defined(__ARM_ARCH_5T__) && \ |
| !defined(__ARM_ARCH_5TE__) && \ |
| !defined(__ARM_ARCH_5TEJ__) && \ |
| !defined(__ARM_ARCH_6__) && \ |
| !defined(__ARM_ARCH_6J__) && \ |
| !defined(__ARM_ARCH_6K__) && \ |
| !defined(__ARM_ARCH_6Z__) && \ |
| !defined(__ARM_ARCH_6ZK__) && \ |
| !defined(__ARM_ARCH_6T2__) |
| |
| // ARMv7 and newer support native unaligned accesses, but only of 16-bit |
| // and 32-bit values (not 64-bit); older versions either raise a fatal signal, |
| // do an unaligned read and rotate the words around a bit, or do the reads very |
| // slowly (trip through kernel mode). There's no simple #define that says just |
| // “ARMv7 or higher”, so we have to filter away all ARMv5 and ARMv6 |
| // sub-architectures. Newer gcc (>= 4.6) set an __ARM_FEATURE_ALIGNED #define, |
| // so in time, maybe we can move on to that. |
| // |
| // This is a mess, but there's not much we can do about it. |
| |
| #define UNALIGNED_LOAD16(_p) (*reinterpret_cast<const uint16 *>(_p)) |
| #define UNALIGNED_LOAD32(_p) (*reinterpret_cast<const uint32 *>(_p)) |
| |
| #define UNALIGNED_STORE16(_p, _val) (*reinterpret_cast<uint16 *>(_p) = (_val)) |
| #define UNALIGNED_STORE32(_p, _val) (*reinterpret_cast<uint32 *>(_p) = (_val)) |
| |
| // TODO(sesse): NEON supports unaligned 64-bit loads and stores. |
| // See if that would be more efficient on platforms supporting it, |
| // at least for copies. |
| |
| inline uint64 UNALIGNED_LOAD64(const void *p) { |
| uint64 t; |
| memcpy(&t, p, sizeof t); |
| return t; |
| } |
| |
| inline void UNALIGNED_STORE64(void *p, uint64 v) { |
| memcpy(p, &v, sizeof v); |
| } |
| |
| #else |
| |
| #define NEED_ALIGNED_LOADS |
| |
| // These functions are provided for architectures that don't support |
| // unaligned loads and stores. |
| |
| inline uint16 UNALIGNED_LOAD16(const void *p) { |
| uint16 t; |
| memcpy(&t, p, sizeof t); |
| return t; |
| } |
| |
| inline uint32 UNALIGNED_LOAD32(const void *p) { |
| uint32 t; |
| memcpy(&t, p, sizeof t); |
| return t; |
| } |
| |
| inline uint64 UNALIGNED_LOAD64(const void *p) { |
| uint64 t; |
| memcpy(&t, p, sizeof t); |
| return t; |
| } |
| |
| inline void UNALIGNED_STORE16(void *p, uint16 v) { |
| memcpy(p, &v, sizeof v); |
| } |
| |
| inline void UNALIGNED_STORE32(void *p, uint32 v) { |
| memcpy(p, &v, sizeof v); |
| } |
| |
| inline void UNALIGNED_STORE64(void *p, uint64 v) { |
| memcpy(p, &v, sizeof v); |
| } |
| |
| #endif |
| |
| } // End namespace CLD2 |
| |
| #endif // BASE_PORT_H_ |