md: Factor out RAID6 algorithms into lib/

We'll want to use these in btrfs too.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 117 insertions, 0 deletions

diff --git a/lib/raid6/raid6int.uc b/lib/raid6/raid6int.uc
new file mode 100644
index 000000000000..f9bf9cba357f
--- /dev/null
+++ b/lib/raid6/raid6int.uc
@@ -0,0 +1,117 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ *   Copyright 2002-2004 H. Peter Anvin - All Rights Reserved
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
+ *   Boston MA 02111-1307, USA; either version 2 of the License, or
+ *   (at your option) any later version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * raid6int$#.c
+ *
+ * $#-way unrolled portable integer math RAID-6 instruction set
+ *
+ * This file is postprocessed using unroll.pl
+ */
+
+#include <linux/raid/pq.h>
+
+/*
+ * This is the C data type to use
+ */
+
+/* Change this from BITS_PER_LONG if there is something better... */
+#if BITS_PER_LONG == 64
+# define NBYTES(x) ((x) * 0x0101010101010101UL)
+# define NSIZE  8
+# define NSHIFT 3
+# define NSTRING "64"
+typedef u64 unative_t;
+#else
+# define NBYTES(x) ((x) * 0x01010101U)
+# define NSIZE  4
+# define NSHIFT 2
+# define NSTRING "32"
+typedef u32 unative_t;
+#endif
+
+
+
+/*
+ * IA-64 wants insane amounts of unrolling.  On other architectures that
+ * is just a waste of space.
+ */
+#if ($# <= 8) || defined(__ia64__)
+
+
+/*
+ * These sub-operations are separate inlines since they can sometimes be
+ * specially optimized using architecture-specific hacks.
+ */
+
+/*
+ * The SHLBYTE() operation shifts each byte left by 1, *not*
+ * rolling over into the next byte
+ */
+static inline __attribute_const__ unative_t SHLBYTE(unative_t v)
+{
+        unative_t vv;
+
+        vv = (v << 1) & NBYTES(0xfe);
+        return vv;
+}
+
+/*
+ * The MASK() operation returns 0xFF in any byte for which the high
+ * bit is 1, 0x00 for any byte for which the high bit is 0.
+ */
+static inline __attribute_const__ unative_t MASK(unative_t v)
+{
+        unative_t vv;
+
+        vv = v & NBYTES(0x80);
+        vv = (vv << 1) - (vv >> 7); /* Overflow on the top bit is OK */
+        return vv;
+}
+
+
+static void raid6_int$#_gen_syndrome(int disks, size_t bytes, void **ptrs)
+{
+        u8 **dptr = (u8 **)ptrs;
+        u8 *p, *q;
+        int d, z, z0;
+
+        unative_t wd$$, wq$$, wp$$, w1$$, w2$$;
+
+        z0 = disks - 3;         /* Highest data disk */
+        p = dptr[z0+1];         /* XOR parity */
+        q = dptr[z0+2];         /* RS syndrome */
+
+        for ( d = 0 ; d < bytes ; d += NSIZE*$# ) {
+                wq$$ = wp$$ = *(unative_t *)&dptr[z0][d+$$*NSIZE];
+                for ( z = z0-1 ; z >= 0 ; z-- ) {
+                        wd$$ = *(unative_t *)&dptr[z][d+$$*NSIZE];
+                        wp$$ ^= wd$$;
+                        w2$$ = MASK(wq$$);
+                        w1$$ = SHLBYTE(wq$$);
+                        w2$$ &= NBYTES(0x1d);
+                        w1$$ ^= w2$$;
+                        wq$$ = w1$$ ^ wd$$;
+                }
+                *(unative_t *)&p[d+NSIZE*$$] = wp$$;
+                *(unative_t *)&q[d+NSIZE*$$] = wq$$;
+        }
+}
+
+const struct raid6_calls raid6_intx$# = {
+        raid6_int$#_gen_syndrome,
+        NULL,           /* always valid */
+        "int" NSTRING "x$#",
+        0
+};
+
+#endif