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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_