Big endian fix: load_u24_unaligned() must be consistent with loaded_u32_to_u24()

[wimlib] / include / wimlib / unaligned.h

diff --git a/include/wimlib/unaligned.h b/include/wimlib/unaligned.h
index ccc86f016a3ab9a1638e49a1bf42891e437d0a8e..3fd35a4df107e7e9140c9603e45fc6445405ebd6 100644 (file)
--- a/include/wimlib/unaligned.h
+++ b/include/wimlib/unaligned.h
@@ -3,6 +3,9 @@
  *
  * Inline functions for unaligned memory accesses.
  *
  *
  * 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.
  */
  * The author dedicates this file to the public domain.
  * You can do whatever you want with this file.
  */


@@ -46,26 +49,6 @@ DEFINE_UNALIGNED_TYPE(machine_word_t);
 #define load_word_unaligned    load_machine_word_t_unaligned
 #define store_word_unaligned   store_machine_word_t_unaligned
 
 #define load_word_unaligned    load_machine_word_t_unaligned
 #define store_word_unaligned   store_machine_word_t_unaligned
 

-static inline void
-copy_word_unaligned(const void *src, void *dst)
-{
-       store_word_unaligned(load_word_unaligned(src), dst);
-}
-
-static inline machine_word_t
-repeat_byte(u8 b)
-{
-       machine_word_t v;
-
-       BUILD_BUG_ON(WORDSIZE != 4 && WORDSIZE != 8);
-
-       v = b;
-       v |= v << 8;
-       v |= v << 16;
-       v |= v << ((WORDSIZE == 8) ? 32 : 0);
-       return v;
-}
-

 static inline u16
 get_unaligned_u16_le(const void *p)
 {
 static inline u16
 get_unaligned_u16_le(const void *p)
 {


@@ -126,4 +109,42 @@ put_unaligned_u32_le(u32 v, void *p)
        }
 }
 
        }
 }
 

+/*
+ * 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 */
 #endif /* _WIMLIB_UNALIGNED_H */