Avoid accessing unaligned 32-bit values (does not work on SPARC)

CVS patchset: 286
CVS date: 2001/07/16 09:22:38

1 files changed, 14 insertions, 4 deletions

diff --git a/src/libac3/bitstream.c b/src/libac3/bitstream.c
index 7e9bd1f66..6e2e36497 100644
--- a/src/libac3/bitstream.c
+++ b/src/libac3/bitstream.c
@@ -22,6 +22,7 @@
  */
 
 #include <inttypes.h>
+#include <stddef.h>
 #include <stdlib.h>
 #include <stdio.h>
 
@@ -31,22 +32,31 @@
 
 #define BUFFER_SIZE 4096
 
-static uint8_t *buffer_start;
+struct uint32_alignment {
+    char        a;
+    uint32_t    b;
+};
+#define UINT32_ALIGNMENT        offsetof(struct uint32_alignment, b)
+
+
+static uint32_t *buffer_start;
 
 uint32_t bits_left;
 uint32_t current_word;
 
 void bitstream_set_ptr (uint8_t * buf)
 {
-    buffer_start = buf;
+    int align = (long)buf & (UINT32_ALIGNMENT-1);
+    buffer_start = (uint32_t *) (buf - align);
     bits_left = 0;
+    if (align > 0) bitstream_get(align * 8);
 }
 
 static inline void
 bitstream_fill_current()
 {
-    current_word = *((uint32_t*)buffer_start)++;
-    current_word = swab32(current_word);
+    uint32_t tmp_word = *buffer_start++;
+    current_word = swab32(tmp_word);
 }
 
 //