LXR linux/arch/openrisc/lib/memcpy.c

   1/*
   2 * arch/openrisc/lib/memcpy.c
   3 *
   4 * Optimized memory copy routines for openrisc.  These are mostly copied
   5 * from ohter sources but slightly entended based on ideas discuassed in
   6 * #openrisc.
   7 *
   8 * The word unroll implementation is an extension to the arm byte
   9 * unrolled implementation, but using word copies (if things are
  10 * properly aligned)
  11 *
  12 * The great arm loop unroll algorithm can be found at:
  13 *  arch/arm/boot/compressed/string.c
  14 */
  15
  16#include <linux/export.h>
  17
  18#include <linux/string.h>
  19
  20#ifdef CONFIG_OR1K_1200
  21/*
  22 * Do memcpy with word copies and loop unrolling. This gives the
  23 * best performance on the OR1200 and MOR1KX archirectures
  24 */
  25void *memcpy(void *dest, __const void *src, __kernel_size_t n)
  26{
  27        int i = 0;
  28        unsigned char *d, *s;
  29        uint32_t *dest_w = (uint32_t *)dest, *src_w = (uint32_t *)src;
  30
  31        /* If both source and dest are word aligned copy words */
  32        if (!((unsigned int)dest_w & 3) && !((unsigned int)src_w & 3)) {
  33                /* Copy 32 bytes per loop */
  34                for (i = n >> 5; i > 0; i--) {
  35                        *dest_w++ = *src_w++;
  36                        *dest_w++ = *src_w++;
  37                        *dest_w++ = *src_w++;
  38                        *dest_w++ = *src_w++;
  39                        *dest_w++ = *src_w++;
  40                        *dest_w++ = *src_w++;
  41                        *dest_w++ = *src_w++;
  42                        *dest_w++ = *src_w++;
  43                }
  44
  45                if (n & 1 << 4) {
  46                        *dest_w++ = *src_w++;
  47                        *dest_w++ = *src_w++;
  48                        *dest_w++ = *src_w++;
  49                        *dest_w++ = *src_w++;
  50                }
  51
  52                if (n & 1 << 3) {
  53                        *dest_w++ = *src_w++;
  54                        *dest_w++ = *src_w++;
  55                }
  56
  57                if (n & 1 << 2)
  58                        *dest_w++ = *src_w++;
  59
  60                d = (unsigned char *)dest_w;
  61                s = (unsigned char *)src_w;
  62
  63        } else {
  64                d = (unsigned char *)dest_w;
  65                s = (unsigned char *)src_w;
  66
  67                for (i = n >> 3; i > 0; i--) {
  68                        *d++ = *s++;
  69                        *d++ = *s++;
  70                        *d++ = *s++;
  71                        *d++ = *s++;
  72                        *d++ = *s++;
  73                        *d++ = *s++;
  74                        *d++ = *s++;
  75                        *d++ = *s++;
  76                }
  77
  78                if (n & 1 << 2) {
  79                        *d++ = *s++;
  80                        *d++ = *s++;
  81                        *d++ = *s++;
  82                        *d++ = *s++;
  83                }
  84        }
  85
  86        if (n & 1 << 1) {
  87                *d++ = *s++;
  88                *d++ = *s++;
  89        }
  90
  91        if (n & 1)
  92                *d++ = *s++;
  93
  94        return dest;
  95}
  96#else
  97/*
  98 * Use word copies but no loop unrolling as we cannot assume there
  99 * will be benefits on the archirecture
 100 */
 101void *memcpy(void *dest, __const void *src, __kernel_size_t n)
 102{
 103        unsigned char *d = (unsigned char *)dest, *s = (unsigned char *)src;
 104        uint32_t *dest_w = (uint32_t *)dest, *src_w = (uint32_t *)src;
 105
 106        /* If both source and dest are word aligned copy words */
 107        if (!((unsigned int)dest_w & 3) && !((unsigned int)src_w & 3)) {
 108                for (; n >= 4; n -= 4)
 109                        *dest_w++ = *src_w++;
 110        }
 111
 112        d = (unsigned char *)dest_w;
 113        s = (unsigned char *)src_w;
 114
 115        /* For remaining or if not aligned, copy bytes */
 116        for (; n >= 1; n -= 1)
 117                *d++ = *s++;
 118
 119        return dest;
 120
 121}
 122#endif
 123
 124EXPORT_SYMBOL(memcpy);
 125