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-rw-r--r--arch/alpha/include/asm/byteorder.h47
1 files changed, 47 insertions, 0 deletions
diff --git a/arch/alpha/include/asm/byteorder.h b/arch/alpha/include/asm/byteorder.h
new file mode 100644
index 00000000000..58e958fc7f1
--- /dev/null
+++ b/arch/alpha/include/asm/byteorder.h
@@ -0,0 +1,47 @@
+#ifndef _ALPHA_BYTEORDER_H
+#define _ALPHA_BYTEORDER_H
+
+#include <asm/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__ */
+
+#define __BYTEORDER_HAS_U64__
+
+#include <linux/byteorder/little_endian.h>
+
+#endif /* _ALPHA_BYTEORDER_H */