1 files changed, 42 insertions, 0 deletions

diff --git a/arch/alpha/include/uapi/asm/swab.h b/arch/alpha/include/uapi/asm/swab.h
new file mode 100644
index 000000000000..4d682b16c7c4
--- /dev/null
+++ b/arch/alpha/include/uapi/asm/swab.h
@@ -0,0 +1,42 @@
+#ifndef _ALPHA_SWAB_H
+#define _ALPHA_SWAB_H
+
+#include <linux/types.h>
+#include <linux/compiler.h>
+#include <asm/compiler.h>
+
+#ifdef __GNUC__
+
+static inline __attribute_const__ __u32 __arch_swab32(__u32 x)
+{
+        /*
+         * Unfortunately, we can't use the 6 instruction sequence
+         * on ev6 since the latency of the UNPKBW is 3, which is
+         * pretty hard to hide.  Just in case a future implementation
+         * has a lower latency, here's the sequence (also by Mike Burrows)
+         *
+         * UNPKBW a0, v0       v0: 00AA00BB00CC00DD
+         * SLL v0, 24, a0      a0: BB00CC00DD000000
+         * BIS v0, a0, a0      a0: BBAACCBBDDCC00DD
+         * EXTWL a0, 6, v0     v0: 000000000000BBAA
+         * ZAP a0, 0xf3, a0    a0: 00000000DDCC0000
+         * ADDL a0, v0, v0     v0: ssssssssDDCCBBAA
+         */
+
+        __u64 t0, t1, t2, t3;
+
+        t0 = __kernel_inslh(x, 7);      /* t0 : 0000000000AABBCC */
+        t1 = __kernel_inswl(x, 3);      /* t1 : 000000CCDD000000 */
+        t1 |= t0;                       /* t1 : 000000CCDDAABBCC */
+        t2 = t1 >> 16;                  /* t2 : 0000000000CCDDAA */
+        t0 = t1 & 0xFF00FF00;           /* t0 : 00000000DD00BB00 */
+        t3 = t2 & 0x00FF00FF;           /* t3 : 0000000000CC00AA */
+        t1 = t0 + t3;                   /* t1 : ssssssssDDCCBBAA */
+
+        return t1;
+}
+#define __arch_swab32 __arch_swab32
+
+#endif /* __GNUC__ */
+
+#endif /* _ALPHA_SWAB_H */