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[2/4] qemu/bswap: Replace bswapXX() by compiler __builtin_bswap()

Message ID 20200923100220.674903-3-philmd@redhat.com
State Superseded
Headers show
Series qemu/bswap: Use compiler __builtin_bswap() | expand

Commit Message

Philippe Mathieu-Daudé Sept. 23, 2020, 10:02 a.m. UTC 
Use the compiler built-in function to byte swap values,
as the compiler is clever and will fold constants.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/qemu/bswap.h | 30 ++++--------------------------
 1 file changed, 4 insertions(+), 26 deletions(-)

Comments

Richard Henderson Sept. 24, 2020, 7:25 p.m. UTC | #1 
On 9/23/20 3:02 AM, Philippe Mathieu-Daudé wrote:
> Use the compiler built-in function to byte swap values,

> as the compiler is clever and will fold constants.

> 

> Suggested-by: Richard Henderson <richard.henderson@linaro.org>

> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> ---

>  include/qemu/bswap.h | 30 ++++--------------------------

>  1 file changed, 4 insertions(+), 26 deletions(-)


Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~
diff mbox series

Patch

diff --git a/include/qemu/bswap.h b/include/qemu/bswap.h
index 8b01c38040c..d1a2f700f2a 100644
--- a/include/qemu/bswap.h
+++ b/include/qemu/bswap.h
@@ -27,32 +27,10 @@  static inline uint64_t bswap64(uint64_t x)
 {
     return bswap_64(x);
 }
-# else
-static inline uint16_t bswap16(uint16_t x)
-{
-    return (((x & 0x00ff) << 8) |
-            ((x & 0xff00) >> 8));
-}
-
-static inline uint32_t bswap32(uint32_t x)
-{
-    return (((x & 0x000000ffU) << 24) |
-            ((x & 0x0000ff00U) <<  8) |
-            ((x & 0x00ff0000U) >>  8) |
-            ((x & 0xff000000U) >> 24));
-}
-
-static inline uint64_t bswap64(uint64_t x)
-{
-    return (((x & 0x00000000000000ffULL) << 56) |
-            ((x & 0x000000000000ff00ULL) << 40) |
-            ((x & 0x0000000000ff0000ULL) << 24) |
-            ((x & 0x00000000ff000000ULL) <<  8) |
-            ((x & 0x000000ff00000000ULL) >>  8) |
-            ((x & 0x0000ff0000000000ULL) >> 24) |
-            ((x & 0x00ff000000000000ULL) >> 40) |
-            ((x & 0xff00000000000000ULL) >> 56));
-}
+#else
+# define bswap16(_x) __builtin_bswap16(_x)
+# define bswap32(_x) __builtin_bswap32(_x)
+# define bswap64(_x) __builtin_bswap64(_x)
 #endif /* ! CONFIG_MACHINE_BSWAP_H */
 
 static inline void bswap16s(uint16_t *s)