linux/lib/raid6/altivec.uc
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   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 * raid6altivec$#.c
  15 *
  16 * $#-way unrolled portable integer math RAID-6 instruction set
  17 *
  18 * This file is postprocessed using unroll.awk
  19 *
  20 * <benh> hpa: in process,
  21 * you can just "steal" the vec unit with enable_kernel_altivec() (but
  22 * bracked this with preempt_disable/enable or in a lock)
  23 */
  24
  25#include <linux/raid/pq.h>
  26
  27#ifdef CONFIG_ALTIVEC
  28
  29#include <altivec.h>
  30#ifdef __KERNEL__
  31# include <asm/cputable.h>
  32# include <asm/switch_to.h>
  33#endif
  34
  35/*
  36 * This is the C data type to use.  We use a vector of
  37 * signed char so vec_cmpgt() will generate the right
  38 * instruction.
  39 */
  40
  41typedef vector signed char unative_t;
  42
  43#define NBYTES(x) ((vector signed char) {x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x})
  44#define NSIZE   sizeof(unative_t)
  45
  46/*
  47 * The SHLBYTE() operation shifts each byte left by 1, *not*
  48 * rolling over into the next byte
  49 */
  50static inline __attribute_const__ unative_t SHLBYTE(unative_t v)
  51{
  52        return vec_add(v,v);
  53}
  54
  55/*
  56 * The MASK() operation returns 0xFF in any byte for which the high
  57 * bit is 1, 0x00 for any byte for which the high bit is 0.
  58 */
  59static inline __attribute_const__ unative_t MASK(unative_t v)
  60{
  61        unative_t zv = NBYTES(0);
  62
  63        /* vec_cmpgt returns a vector bool char; thus the need for the cast */
  64        return (unative_t)vec_cmpgt(zv, v);
  65}
  66
  67
  68/* This is noinline to make damned sure that gcc doesn't move any of the
  69   Altivec code around the enable/disable code */
  70static void noinline
  71raid6_altivec$#_gen_syndrome_real(int disks, size_t bytes, void **ptrs)
  72{
  73        u8 **dptr = (u8 **)ptrs;
  74        u8 *p, *q;
  75        int d, z, z0;
  76
  77        unative_t wd$$, wq$$, wp$$, w1$$, w2$$;
  78        unative_t x1d = NBYTES(0x1d);
  79
  80        z0 = disks - 3;         /* Highest data disk */
  81        p = dptr[z0+1];         /* XOR parity */
  82        q = dptr[z0+2];         /* RS syndrome */
  83
  84        for ( d = 0 ; d < bytes ; d += NSIZE*$# ) {
  85                wq$$ = wp$$ = *(unative_t *)&dptr[z0][d+$$*NSIZE];
  86                for ( z = z0-1 ; z >= 0 ; z-- ) {
  87                        wd$$ = *(unative_t *)&dptr[z][d+$$*NSIZE];
  88                        wp$$ = vec_xor(wp$$, wd$$);
  89                        w2$$ = MASK(wq$$);
  90                        w1$$ = SHLBYTE(wq$$);
  91                        w2$$ = vec_and(w2$$, x1d);
  92                        w1$$ = vec_xor(w1$$, w2$$);
  93                        wq$$ = vec_xor(w1$$, wd$$);
  94                }
  95                *(unative_t *)&p[d+NSIZE*$$] = wp$$;
  96                *(unative_t *)&q[d+NSIZE*$$] = wq$$;
  97        }
  98}
  99
 100static void raid6_altivec$#_gen_syndrome(int disks, size_t bytes, void **ptrs)
 101{
 102        preempt_disable();
 103        enable_kernel_altivec();
 104
 105        raid6_altivec$#_gen_syndrome_real(disks, bytes, ptrs);
 106
 107        preempt_enable();
 108}
 109
 110int raid6_have_altivec(void);
 111#if $# == 1
 112int raid6_have_altivec(void)
 113{
 114        /* This assumes either all CPUs have Altivec or none does */
 115# ifdef __KERNEL__
 116        return cpu_has_feature(CPU_FTR_ALTIVEC);
 117# else
 118        return 1;
 119# endif
 120}
 121#endif
 122
 123const struct raid6_calls raid6_altivec$# = {
 124        raid6_altivec$#_gen_syndrome,
 125        raid6_have_altivec,
 126        "altivecx$#",
 127        0
 128};
 129
 130#endif /* CONFIG_ALTIVEC */
 131
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