payloads/libpayload/libc/memory.c

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