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// 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_
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