src/opt_memcpy.h

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * By Daniel Borkmann <daniel@netsniff-ng.org>
   4  * Copyright 2011 Daniel Borkmann.
   5  * Subject to the GPL, version 2.
   6  */
   7
   8 #ifndef OPT_MEMCPY_H
   9 #define OPT_MEMCPY_H
  10
  11 #ifdef ARCH_X86
  12 #define small_memcpy(dest, src, n)                                       \
  13         do {                                                             \
  14                 register unsigned long int dummy;                        \
  15                 asm volatile ("rep; movsb\n\t"                           \
  16                               : "=&D" (dest), "=&S" (src), "=&c" (dummy) \
  17                               : "0" (dest), "1" (src), "2" (n)           \
  18                               : "memory");                               \
  19         } while(0)
  20
  21 /* From the Linux kernel. */
  22 static inline void *___memcpy(void *__restrict__ dest,
  23                               const void *__restrict__ src, size_t n)
  24 {
  25         int d0, d1, d2;
  26
  27         if (n == 4)
  28                 small_memcpy(dest, src, n);
  29         else
  30                 asm volatile("rep ; movsl\n\t"
  31                              "testb $2,%b4\n\t"
  32                              "je 1f\n\t"
  33                              "movsw\n"
  34                              "1:\ttestb $1,%b4\n\t"
  35                              "je 2f\n\t"
  36                              "movsb\n"
  37                              "2:"
  38                              : "=&c" (d0), "=&D" (d1), "=&S" (d2)
  39                              : "0" (n / 4), "q" (n), "1" ((long)dest), "2" ((long)src)
  40                              : "memory");
  41         return (dest);
  42 }
  43
  44 static inline void *__memcpy_small(void *__restrict__ dest,
  45                                    const void *__restrict__ src, size_t n)
  46 {
  47         return ___memcpy(dest, src, n);
  48 }
  49
  50 /* This one checks CPU flags and sets right variant! */
  51 extern void set_memcpy(void);
  52 extern void *(*____memcpy)(void *__restrict__ dest, const void *__restrict__ src,
  53                            size_t n);
  54
  55 static inline void *__memcpy(void *__restrict__ dest, const void *__restrict__ src,
  56                              size_t n)
  57 {
  58         return ____memcpy(dest, src, n);
  59 }
  60
  61 extern void *__sse_memcpy(void *__restrict__ dest, const void *__restrict__ src, size_t n);
  62 extern void *__sse2_memcpy(void *__restrict__ dest, const void *__restrict__ src, size_t n);
  63 extern void *__mmx_memcpy(void *__restrict__ dest, const void *__restrict__ src, size_t n);
  64 extern void *__mmx2_memcpy(void *__restrict__ dest, const void *__restrict__ src, size_t n);
  65 #else
  66 #include <linux/string.h>
  67 #define set_memcpy()   do {} while(0)
  68
  69 static inline void *__memcpy_small(void *__restrict__ dest,
  70                                    const void *__restrict__ src, size_t n)
  71 {
  72         return __builtin_memcpy(dest, src, n);
  73 }
  74
  75 static inline void *__memcpy(void *__restrict__ dest, const void *__restrict__ src,
  76                              size_t n)
  77 {
  78         return __builtin_memcpy(dest, src, n);
  79 }
  80 #endif /* ARCH_X86 */
  81 #endif /* OPT_MEMCPY_H */