Ticket #1590: patch-mutex.h

--- ../include/mutex.h.orig     Sun May  6 21:19:20 2001
+++ ../include/mutex.h  Sat Mar  6 10:31:57 2004
@@ -482,6 +482,43 @@
  * 'set' mutexes have the value 1, like on Intel; the returned value from
  * MUTEX_SET() is 1 if the mutex previously had its low bit clear, 0 otherwise.
  */
+
+/*
+ * Note from http://cvs.osafoundation.org/index.cgi/osaf/chandler/persistence/db/dbinc/mutex.h?rev=HEAD
+ * by Andi Vajda <andi at osafoundation dot org>
+ * 
+ * Mutexes on Mac OS X work the same way as the standard PowerPC version, but
+ * the assembler syntax is subtly different -- the standard PowerPC version
+ * assembles but doesn't work correctly.  This version makes (unnecessary?)
+ * use of a stupid linker trick: __db_mutex_tas_dummy is never called, but the
+ * ___db_mutex_set label is used as a function name.
+ */
+
+#if defined(__APPLE__) && defined(__MACH__) && defined(__ppc__)
+#warning "Using apple specific mutexes" 
+extern int __db_mutex_set __P((volatile tsl_t *));
+void
+__db_mutex_tas_dummy()
+{
+       __asm__ __volatile__("          \n\
+       .globl  ___db_mutex_set         \n\
+___db_mutex_set:                       \n\
+       lwarx   r5,0,r3                 \n\
+       cmpwi   r5,0                    \n\
+       bne     fail                    \n\
+       addi    r5,r5,1                 \n\
+       stwcx.  r5,0,r3                 \n\
+       beq     success                 \n\
+fail:                                  \n\
+       li      r3,0                    \n\
+       blr                             \n\
+success:                               \n\
+       li      r3,1                    \n\
+       blr");  
+}
+#define        MUTEX_SET(tsl)  __db_mutex_set(tsl)
+#else
+ 
 #define        MUTEX_SET(tsl)  ({              \
        int __one = 1;                  \
        int __r;                        \
@@ -499,6 +536,7 @@
        !(__r & 1);                     \
 })
 
+#endif
 #define        MUTEX_UNSET(tsl)        (*(tsl) = 0)
 #define        MUTEX_INIT(tsl)         MUTEX_UNSET(tsl)
 #endif