newlib/libc/machine/riscv/memcpy.c

   1 /* Copyright (c) 2017  SiFive Inc. All rights reserved.
   2
   3    This copyrighted material is made available to anyone wishing to use,
   4    modify, copy, or redistribute it subject to the terms and conditions
   5    of the FreeBSD License.   This program is distributed in the hope that
   6    it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
   7    including the implied warranties of MERCHANTABILITY or FITNESS FOR
   8    A PARTICULAR PURPOSE.  A copy of this license is available at
   9    http://www.opensource.org/licenses.
  10 */
  11
  12 #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
  13 //memcpy defined in memcpy-asm.S
  14 #else
  15
  16 #include <string.h>
  17 #include <stdint.h>
  18 #include "../../string/local.h"
  19
  20 #define unlikely(X) __builtin_expect (!!(X), 0)
  21
  22 void *
  23 __inhibit_loop_to_libcall
  24 memcpy(void *__restrict aa, const void *__restrict bb, size_t n)
  25 {
  26   #define BODY(a, b, t) { \
  27     t tt = *b; \
  28     a++, b++; \
  29     *(a - 1) = tt; \
  30   }
  31
  32   char *a = (char *)aa;
  33   const char *b = (const char *)bb;
  34   char *end = a + n;
  35   uintptr_t msk = sizeof (long) - 1;
  36   if (unlikely ((((uintptr_t)a & msk) != ((uintptr_t)b & msk))
  37                || n < sizeof (long)))
  38     {
  39 small:
  40       if (__builtin_expect (a < end, 1))
  41         while (a < end)
  42           BODY (a, b, char);
  43       return aa;
  44     }
  45
  46   if (unlikely (((uintptr_t)a & msk) != 0))
  47     while ((uintptr_t)a & msk)
  48       BODY (a, b, char);
  49
  50   long *la = (long *)a;
  51   const long *lb = (const long *)b;
  52   long *lend = (long *)((uintptr_t)end & ~msk);
  53
  54   if (unlikely (lend - la > 8))
  55     {
  56       while (lend - la > 8)
  57         {
  58           long b0 = *lb++;
  59           long b1 = *lb++;
  60           long b2 = *lb++;
  61           long b3 = *lb++;
  62           long b4 = *lb++;
  63           long b5 = *lb++;
  64           long b6 = *lb++;
  65           long b7 = *lb++;
  66           long b8 = *lb++;
  67           *la++ = b0;
  68           *la++ = b1;
  69           *la++ = b2;
  70           *la++ = b3;
  71           *la++ = b4;
  72           *la++ = b5;
  73           *la++ = b6;
  74           *la++ = b7;
  75           *la++ = b8;
  76         }
  77     }
  78
  79   while (la < lend)
  80     BODY (la, lb, long);
  81
  82   a = (char *)la;
  83   b = (const char *)lb;
  84   if (unlikely (a < end))
  85     goto small;
  86   return aa;
  87 }
  88 #endif