unaligned.h: slightly simplify get/put unaligned functions

[wimlib] / include / wimlib / unaligned.h

diff --git a/include/wimlib/unaligned.h b/include/wimlib/unaligned.h
index 9d70806529c0786e0ab7502e4654b6175c709213..d25e76f6d909fb1e61ccd507956d12e56896daff 100644 (file)
--- a/include/wimlib/unaligned.h
+++ b/include/wimlib/unaligned.h
@@ -3,6 +3,9 @@
  *
  * Inline functions for unaligned memory accesses.
  *
+ * Author:     Eric Biggers
+ * Year:       2014, 2015
+ *
  * The author dedicates this file to the public domain.
  * You can do whatever you want with this file.
  */
@@ -10,9 +13,9 @@
 #ifndef _WIMLIB_UNALIGNED_H
 #define _WIMLIB_UNALIGNED_H
 
-#include "compiler.h"
-#include "endianness.h"
-#include "types.h"
+#include "wimlib/compiler.h"
+#include "wimlib/endianness.h"
+#include "wimlib/types.h"
 
 #define DEFINE_UNALIGNED_TYPE(type)                            \
 struct type##_unaligned {                                      \
@@ -31,9 +34,100 @@ store_##type##_unaligned(type val, void *p)                 \
        ((struct type##_unaligned *)p)->v = val;                \
 }
 
+DEFINE_UNALIGNED_TYPE(u16);
+DEFINE_UNALIGNED_TYPE(u32);
+DEFINE_UNALIGNED_TYPE(u64);
 DEFINE_UNALIGNED_TYPE(le16);
 DEFINE_UNALIGNED_TYPE(le32);
 DEFINE_UNALIGNED_TYPE(le64);
+DEFINE_UNALIGNED_TYPE(be16);
+DEFINE_UNALIGNED_TYPE(be32);
+DEFINE_UNALIGNED_TYPE(be64);
 DEFINE_UNALIGNED_TYPE(size_t);
+DEFINE_UNALIGNED_TYPE(machine_word_t);
+
+#define load_word_unaligned    load_machine_word_t_unaligned
+#define store_word_unaligned   store_machine_word_t_unaligned
+
+static inline u16
+get_unaligned_le16(const u8 *p)
+{
+       if (UNALIGNED_ACCESS_IS_FAST)
+               return le16_to_cpu(load_le16_unaligned(p));
+       else
+               return ((u16)p[1] << 8) | p[0];
+}
+
+static inline u32
+get_unaligned_le32(const u8 *p)
+{
+       if (UNALIGNED_ACCESS_IS_FAST)
+               return le32_to_cpu(load_le32_unaligned(p));
+       else
+               return ((u32)p[3] << 24) | ((u32)p[2] << 16) |
+                       ((u32)p[1] << 8) | p[0];
+}
+
+static inline void
+put_unaligned_le16(u16 v, u8 *p)
+{
+       if (UNALIGNED_ACCESS_IS_FAST) {
+               store_le16_unaligned(cpu_to_le16(v), p);
+       } else {
+               p[0] = (u8)(v >> 0);
+               p[1] = (u8)(v >> 8);
+       }
+}
+
+static inline void
+put_unaligned_le32(u32 v, u8 *p)
+{
+       if (UNALIGNED_ACCESS_IS_FAST) {
+               store_le32_unaligned(cpu_to_le32(v), p);
+       } else {
+               p[0] = (u8)(v >> 0);
+               p[1] = (u8)(v >> 8);
+               p[2] = (u8)(v >> 16);
+               p[3] = (u8)(v >> 24);
+       }
+}
+
+/*
+ * Given a 32-bit value that was loaded with the platform's native endianness,
+ * return a 32-bit value whose high-order 8 bits are 0 and whose low-order 24
+ * bits contain the first 3 bytes, arranged in octets in a platform-dependent
+ * order, at the memory location from which the input 32-bit value was loaded.
+ */
+static inline u32
+loaded_u32_to_u24(u32 v)
+{
+       if (CPU_IS_LITTLE_ENDIAN)
+               return v & 0xFFFFFF;
+       else
+               return v >> 8;
+}
+
+/*
+ * Load the next 3 bytes from the memory location @p into the 24 low-order bits
+ * of a 32-bit value.  The order in which the 3 bytes will be arranged as octets
+ * in the 24 bits is platform-dependent.  At least LOAD_U24_REQUIRED_NBYTES
+ * bytes must be available at @p; note that this may be more than 3.
+ */
+static inline u32
+load_u24_unaligned(const u8 *p)
+{
+#if UNALIGNED_ACCESS_IS_FAST
+#  define LOAD_U24_REQUIRED_NBYTES 4
+       return loaded_u32_to_u24(load_u32_unaligned(p));
+#else
+#  define LOAD_U24_REQUIRED_NBYTES 3
+#  if CPU_IS_BIG_ENDIAN
+       return ((u32)p[2] << 0) | ((u32)p[1] << 8) | ((u32)p[0] << 16);
+#  else
+       return ((u32)p[0] << 0) | ((u32)p[1] << 8) | ((u32)p[2] << 16);
+#  endif
+#endif
+}
+
 
 #endif /* _WIMLIB_UNALIGNED_H */