Add header for access to potentially unaligned data.

[sliver-openvswitch.git] / lib / unaligned.h

diff --git a/lib/unaligned.h b/lib/unaligned.h
new file mode 100644 (file)
index 0000000..fb167a4
--- /dev/null
+++ b/lib/unaligned.h
@@ -0,0 +1,122 @@
+/*
+ * Copyright (c) 2010 Nicira Networks.
+ *
+ * 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.
+ */
+
+#ifndef UNALIGNED_H
+#define UNALIGNED_H 1
+
+#include <stdint.h>
+#include "xtoxll.h"
+
+/* Public API. */
+static inline uint16_t get_unaligned_u16(const uint16_t *);
+static inline uint32_t get_unaligned_u32(const uint32_t *);
+static inline uint64_t get_unaligned_u64(const uint64_t *);
+static inline void put_unaligned_u16(uint16_t *, uint16_t);
+static inline void put_unaligned_u32(uint32_t *, uint32_t);
+static inline void put_unaligned_u64(uint64_t *, uint64_t);
+
+#ifdef __GNUC__
+/* GCC implementations. */
+#define GCC_UNALIGNED_ACCESSORS(SIZE)                       \
+struct unaligned_u##SIZE {                                  \
+    uint##SIZE##_t x __attribute__((__packed__));           \
+};                                                          \
+static inline struct unaligned_u##SIZE *                    \
+unaligned_u##SIZE(const uint##SIZE##_t *p)                  \
+{                                                           \
+    return (struct unaligned_u##SIZE *) p;                  \
+}                                                           \
+                                                            \
+static inline uint##SIZE##_t                                \
+get_unaligned_u##SIZE(const uint##SIZE##_t *p)              \
+{                                                           \
+    return unaligned_u##SIZE(p)->x;                         \
+}                                                           \
+                                                            \
+static inline void                                          \
+put_unaligned_u##SIZE(uint##SIZE##_t *p, uint##SIZE##_t x)  \
+{                                                           \
+    unaligned_u##SIZE(p)->x = x;                            \
+}
+
+GCC_UNALIGNED_ACCESSORS(16);
+GCC_UNALIGNED_ACCESSORS(32);
+GCC_UNALIGNED_ACCESSORS(64);
+#else
+/* Generic implementations. */
+
+static inline uint16_t get_unaligned_u16(const uint16_t *p_)
+{
+    const uint8_t *p = (const uint8_t *) p_;
+    return ntohs((p[0] << 8) | p[1]);
+}
+
+static inline void put_unaligned_u16(uint16_t *p_, uint16_t x_)
+{
+    uint8_t *p = (uint8_t *) p_;
+    uint16_t x = ntohs(x_);
+
+    p[0] = x >> 8;
+    p[1] = x;
+}
+
+static inline uint32_t get_unaligned_u32(const uint32_t *p_)
+{
+    const uint8_t *p = (const uint8_t *) p_;
+    return ntohl((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
+}
+
+static inline void put_unaligned_u32(uint32_t *p_, uint32_t x_)
+{
+    uint8_t *p = (uint8_t *) p_;
+    uint32_t x = ntohl(x_);
+
+    p[0] = x >> 24;
+    p[1] = x >> 16;
+    p[2] = x >> 8;
+    p[3] = x;
+}
+
+static inline uint64_t get_unaligned_u64(const uint64_t *p_)
+{
+    const uint8_t *p = (const uint8_t *) p_;
+    return ntohll(((uint64_t) p[0] << 56)
+                  | ((uint64_t) p[1] << 48)
+                  | ((uint64_t) p[2] << 40)
+                  | ((uint64_t) p[3] << 32)
+                  | (p[4] << 24)
+                  | (p[5] << 16)
+                  | (p[6] << 8)
+                  | p[7]);
+}
+
+static inline void put_unaligned_u64(uint64_t *p_, uint64_t x_)
+{
+    uint8_t *p = (uint8_t *) p_;
+    uint64_t x = ntohll(x_);
+
+    p[0] = x >> 56;
+    p[1] = x >> 48;
+    p[2] = x >> 40;
+    p[3] = x >> 32;
+    p[4] = x >> 24;
+    p[5] = x >> 16;
+    p[6] = x >> 8;
+    p[7] = x;
+}
+#endif
+
+#endif /* unaligned.h */