raid6.c

   1 /* -*- linux-c -*- ------------------------------------------------------- *
   2  *
   3  *   Copyright 2002-2004 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   8  *   Boston MA 02111-1307, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 /*
  14  * Added helpers for unaligned native int access
  15  */
  16
  17 /*
  18  * raid6int1.c
  19  *
  20  * 1-way unrolled portable integer math RAID-6 instruction set
  21  *
  22  * This file was postprocessed using unroll.pl and then ported to userspace
  23  */
  24 #include <stdint.h>
  25 #include <unistd.h>
  26 #include "kerncompat.h"
  27 #include "ctree.h"
  28 #include "disk-io.h"
  29
  30 /*
  31  * This is the C data type to use
  32  */
  33
  34 /* Change this from BITS_PER_LONG if there is something better... */
  35 #if BITS_PER_LONG == 64
  36 # define NBYTES(x) ((x) * 0x0101010101010101UL)
  37 # define NSIZE  8
  38 # define NSHIFT 3
  39 typedef uint64_t unative_t;
  40 #define put_unaligned_native(val,p)     put_unaligned_64((val),(p))
  41 #define get_unaligned_native(p)         get_unaligned_64((p))
  42 #else
  43 # define NBYTES(x) ((x) * 0x01010101U)
  44 # define NSIZE  4
  45 # define NSHIFT 2
  46 typedef uint32_t unative_t;
  47 #define put_unaligned_native(val,p)     put_unaligned_32((val),(p))
  48 #define get_unaligned_native(p)         get_unaligned_32((p))
  49 #endif
  50
  51 /*
  52  * These sub-operations are separate inlines since they can sometimes be
  53  * specially optimized using architecture-specific hacks.
  54  */
  55
  56 /*
  57  * The SHLBYTE() operation shifts each byte left by 1, *not*
  58  * rolling over into the next byte
  59  */
  60 static inline __attribute_const__ unative_t SHLBYTE(unative_t v)
  61 {
  62         unative_t vv;
  63
  64         vv = (v << 1) & NBYTES(0xfe);
  65         return vv;
  66 }
  67
  68 /*
  69  * The MASK() operation returns 0xFF in any byte for which the high
  70  * bit is 1, 0x00 for any byte for which the high bit is 0.
  71  */
  72 static inline __attribute_const__ unative_t MASK(unative_t v)
  73 {
  74         unative_t vv;
  75
  76         vv = v & NBYTES(0x80);
  77         vv = (vv << 1) - (vv >> 7); /* Overflow on the top bit is OK */
  78         return vv;
  79 }
  80
  81
  82 void raid6_gen_syndrome(int disks, size_t bytes, void **ptrs)
  83 {
  84         uint8_t **dptr = (uint8_t **)ptrs;
  85         uint8_t *p, *q;
  86         int d, z, z0;
  87
  88         unative_t wd0, wq0, wp0, w10, w20;
  89
  90         z0 = disks - 3;         /* Highest data disk */
  91         p = dptr[z0+1];         /* XOR parity */
  92         q = dptr[z0+2];         /* RS syndrome */
  93
  94         for ( d = 0 ; d < bytes ; d += NSIZE*1 ) {
  95                 wq0 = wp0 = get_unaligned_native(&dptr[z0][d+0*NSIZE]);
  96                 for ( z = z0-1 ; z >= 0 ; z-- ) {
  97                         wd0 = get_unaligned_native(&dptr[z][d+0*NSIZE]);
  98                         wp0 ^= wd0;
  99                         w20 = MASK(wq0);
 100                         w10 = SHLBYTE(wq0);
 101                         w20 &= NBYTES(0x1d);
 102                         w10 ^= w20;
 103                         wq0 = w10 ^ wd0;
 104                 }
 105                 put_unaligned_native(wp0, &p[d+NSIZE*0]);
 106                 put_unaligned_native(wq0, &q[d+NSIZE*0]);
 107         }
 108 }
 109