This patch from Andi Kleen speeds up swab64 on x86 cpus that
implement the bswapl significatnly. It has been in the XFS tree
for a while and shows nice improvements when't it's heavily used.
--- linux/include/asm-i386/byteorder.h Fri Jun 25 19:32:48 1999
+++ linux/include/asm-i386/byteorder.h Mon Oct 14 20:52:05 2002
@@ -24,21 +24,41 @@
return x;
}
+/* gcc should generate this for open coded C now too. May be worth switching to
+ it because inline assembly cannot be scheduled. -AK */
static __inline__ __const__ __u16 ___arch__swab16(__u16 x)
{
- __asm__("xchgb %b0,%h0" /* swap bytes */ \
- : "=q" (x) \
- : "0" (x)); \
+ __asm__("xchgb %b0,%h0" /* swap bytes */
+ : "=q" (x)
+ : "0" (x));
return x;
}
+
+static inline __u64 ___arch__swab64(__u64 val)
+{
+ union {
+ struct { __u32 a,b; } s;
+ __u64 u;
+ } v;
+ v.u = val;
+#ifdef CONFIG_X86_BSWAP
+ asm("bswapl %0 ; bswapl %1 ; xchgl %0,%1"
+ : "=r" (v.s.a), "=r" (v.s.b)
+ : "0" (v.s.a), "1" (v.s.b));
+#else
+ v.s.a = ___arch__swab32(v.s.a);
+ v.s.b = ___arch__swab32(v.s.b);
+ asm("xchgl %0,%1" : "=r" (v.s.a), "=r" (v.s.b) : "0" (v.s.a), "1" (v.s.b));
+#endif
+ return v.u;
+}
+
+#define __arch__swab64(x) ___arch__swab64(x)
#define __arch__swab32(x) ___arch__swab32(x)
#define __arch__swab16(x) ___arch__swab16(x)
-#if !defined(__STRICT_ANSI__) || defined(__KERNEL__)
-# define __BYTEORDER_HAS_U64__
-# define __SWAB_64_THRU_32__
-#endif
+#define __BYTEORDER_HAS_U64__
#endif /* __GNUC__ */
-
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This archive was generated by hypermail 2b29 : Sat Nov 30 2002 - 22:00:22 EST