Introduce likely() and unlikely() macros, use to give gcc hints about which branch is likely to be taken in a conditional, use them in the midi player for a small speedup, use instead of similar EXPECT macros in tremor and use in mpegplayer

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19162 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 9 insertions, 0 deletions

diff --git a/firmware/export/system.h b/firmware/export/system.h
index 71422e17d6..cce7df6884 100644
--- a/firmware/export/system.h
+++ b/firmware/export/system.h
@@ -168,6 +168,15 @@ int get_cpu_boost_counter(void);
 #define TYPE_FROM_MEMBER(type, memberptr, membername) \
     ((type *)((intptr_t)(memberptr) - OFFSETOF(type, membername)))
 
+/* Use to give gcc hints on which branch is most likely taken */
+#if defined(__GNUC__) && __GNUC__ >= 3
+#define likely(x)   __builtin_expect(!!(x), 1)
+#define unlikely(x) __builtin_expect(!!(x), 0)
+#else
+#define likely(x)   (x)
+#define unlikely(x) (x)
+#endif
+
 /* returns index of first set bit + 1 or 0 if no bits are set */
 int find_first_set_bit(uint32_t val);