diff --git a/src/atomic.h b/src/atomic.h
index 12fb6647..a9e1485e 100644
--- a/src/atomic.h
+++ b/src/atomic.h
@@ -19,10 +19,94 @@
 #ifndef HTSATOMIC_H__
 #define HTSATOMIC_H__
 
-static inline int 
+/**
+ * Atomically add 'incr' to *ptr and return the previous value
+ */
+
+
+
+#if defined(linux) && __GNUC__ >= 4 && __GNUC_MINOR__ >=3 
+
+static inline int
 atomic_add(volatile int *ptr, int incr)
 {
   return __sync_fetch_and_add(ptr, incr);
 }
 
+#elif defined(__i386__) || defined(__x86_64__)
+static inline int
+atomic_add(volatile int *ptr, int incr)
+{
+  int r;
+  asm volatile("lock; xaddl %0, %1" :
+	       "=r"(r), "=m"(*ptr) : "0" (incr), "m" (*ptr) : "memory");
+  return r;
+}
+#elif defined(WII)
+
+#include <ogc/machine/processor.h>
+
+static inline int
+atomic_add(volatile int *ptr, int incr)
+{
+  int r, level;
+
+  /*
+   * Last time i checked libogc's context switcher did not do the
+   * necessary operations to clear locks held by lwarx/stwcx.
+   * Thus we need to resort to other means
+   */
+
+  _CPU_ISR_Disable(level);
+
+  r = *ptr;
+  *ptr = *ptr + incr;
+
+  _CPU_ISR_Restore(level);
+
+  return r;
+}
+#elif defined(__ppc__) || defined(__PPC__)
+
+/* somewhat based on code from darwin gcc  */
+static inline int
+atomic_add (volatile int *ptr, int incr)
+{
+  int tmp, res;
+  asm volatile("0:\n"
+               "lwarx  %1,0,%2\n"
+               "add%I3 %0,%1,%3\n"
+               "stwcx. %0,0,%2\n"
+               "bne-   0b\n"
+               : "=&r"(tmp), "=&b"(res)
+               : "r" (ptr), "Ir"(incr)
+               : "cr0", "memory");
+  
+  return res;
+}
+
+#elif defined(__arm__) 
+
+static inline int 
+atomic_add(volatile int *ptr, int val)
+{
+  int a, b, c;
+
+  asm volatile(  "0:\n\t"
+		 "ldr %0, [%3]\n\t"
+		 "add %1, %0, %4\n\t"
+		 "swp %2, %1, [%3]\n\t"
+		 "cmp %0, %2\n\t"
+		 "swpne %1, %2, [%3]\n\t"
+		 "bne 0b"
+		 : "=&r" (a), "=&r" (b), "=&r" (c)
+		 : "r" (ptr), "r" (val)
+		 : "cc", "memory");
+  return a;
+}
+
+#else
+#error Missing atomic ops
+#endif
+
 #endif /* HTSATOMIC_H__ */