payloads/libpayload/libc/memory.c

   1 /*
   2  *
   3  * It has originally been taken from the HelenOS project
   4  * (http://www.helenos.eu), and slightly modified for our purposes.
   5  *
   6  * Copyright (c) 2005 Martin Decky
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  *
  13  * - Redistributions of source code must retain the above copyright
  14  *   notice, this list of conditions and the following disclaimer.
  15  * - Redistributions in binary form must reproduce the above copyright
  16  *   notice, this list of conditions and the following disclaimer in the
  17  *   documentation and/or other materials provided with the distribution.
  18  * - The name of the author may not be used to endorse or promote products
  19  *   derived from this software without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  */
  32
  33 #include <libpayload.h>
  34
  35 static void *default_memset(void *const s, const int c, size_t n)
  36 {
  37         size_t i;
  38         u8 *dst = s;
  39         unsigned long w = c & 0xff;
  40
  41         const u8 *const aligned_start =
  42                 (const u8 *)ALIGN_UP((uintptr_t)dst, sizeof(unsigned long));
  43         for (; n > 0 && dst != aligned_start; --n, ++dst)
  44                 *dst = (u8)c;
  45
  46         for (i = 1; i < sizeof(unsigned long); i <<= 1)
  47                 w = (w << (i * 8)) | w;
  48
  49         for (i = 0; i < n / sizeof(unsigned long); i++)
  50                 ((unsigned long *)dst)[i] = w;
  51
  52         dst += i * sizeof(unsigned long);
  53
  54         for (i = 0; i < n % sizeof(unsigned long); i++)
  55                 dst[i] = (u8)c;
  56
  57         return s;
  58 }
  59
  60 void *memset(void *s, int c, size_t n)
  61         __attribute__((weak, alias("default_memset")));
  62
  63 static void *default_memcpy(void *dst, const void *src, size_t n)
  64 {
  65         size_t i;
  66         void *ret = dst;
  67
  68         if (IS_ALIGNED((uintptr_t)dst, sizeof(unsigned long)) &&
  69             IS_ALIGNED((uintptr_t)src, sizeof(unsigned long))) {
  70                 for (i = 0; i < n / sizeof(unsigned long); i++)
  71                         ((unsigned long *)dst)[i] = ((unsigned long *)src)[i];
  72
  73                 src += i * sizeof(unsigned long);
  74                 dst += i * sizeof(unsigned long);
  75                 n -= i * sizeof(unsigned long);
  76         }
  77
  78         for (i = 0; i < n; i++)
  79                 ((u8 *)dst)[i] = ((u8 *)src)[i];
  80
  81         return ret;
  82 }
  83
  84 void *memcpy(void *dst, const void *src, size_t n)
  85         __attribute__((weak, alias("default_memcpy")));
  86
  87 static void *default_memmove(void *dst, const void *src, size_t n)
  88 {
  89         size_t offs;
  90         ssize_t i;
  91
  92         if (src > dst)
  93                 return default_memcpy(dst, src, n);
  94
  95         if (!IS_ALIGNED((uintptr_t)dst, sizeof(unsigned long)) ||
  96             !IS_ALIGNED((uintptr_t)src, sizeof(unsigned long))) {
  97                 for (i = n - 1; i >= 0; i--)
  98                         ((u8 *)dst)[i] = ((u8 *)src)[i];
  99                 return dst;
 100         }
 101
 102         offs = n - (n % sizeof(unsigned long));
 103
 104         for (i = (n % sizeof(unsigned long)) - 1; i >= 0; i--)
 105                 ((u8 *)dst)[i + offs] = ((u8 *)src)[i + offs];
 106
 107         for (i = n / sizeof(unsigned long) - 1; i >= 0; i--)
 108                 ((unsigned long *)dst)[i] = ((unsigned long *)src)[i];
 109
 110         return dst;
 111 }
 112
 113 void *memmove(void *dst, const void *src, size_t n)
 114         __attribute__((weak, alias("default_memmove")));
 115
 116 /**
 117  * Compare two memory areas.
 118  *
 119  * @param s1 Pointer to the first area to compare.
 120  * @param s2 Pointer to the second area to compare.
 121  * @param n Size of the first area in bytes (both must have the same length).
 122  * @return If n is 0, return zero. Otherwise, return a value less than, equal
 123  *         to, or greater than zero if s1 is found less than, equal to, or
 124  *         greater than s2 respectively.
 125  */
 126
 127 static int default_memcmp(const void *s1, const void *s2, size_t n)
 128 {
 129         size_t i = 0;
 130         const unsigned long *w1 = s1, *w2 = s2;
 131
 132         if (IS_ALIGNED((uintptr_t)s1, sizeof(unsigned long)) &&
 133             IS_ALIGNED((uintptr_t)s2, sizeof(unsigned long)))
 134                 for (; i < n / sizeof(unsigned long); i++)
 135                         if (w1[i] != w2[i])
 136                                 break; /* fall through to find differing byte */
 137
 138         for (i *= sizeof(unsigned long); i < n; i++)
 139                 if (((u8 *)s1)[i] != ((u8 *)s2)[i])
 140                         return ((u8 *)s1)[i] - ((u8 *)s2)[i];
 141
 142         return 0;
 143 }
 144
 145 int memcmp(const void *s1, const void *s2, size_t n)
 146         __attribute__((weak, alias("default_memcmp")));
 147
 148 void *memchr(const void *s, int c, size_t n)
 149 {
 150         unsigned char *p = (unsigned char *)s;
 151         while (n--)
 152                 if (*p != (unsigned char)c)
 153                         p++;
 154                 else
 155                         return p;
 156         return 0;
 157 }