release/src/router/dropbear/libtommath/etc/tune.c

   1 /* Tune the Karatsuba parameters
   2  *
   3  * Tom St Denis, tomstdenis@gmail.com
   4  */
   5 #include <tommath.h>
   6 #include <time.h>
   7
   8 /* how many times todo each size mult.  Depends on your computer.  For slow computers
   9  * this can be low like 5 or 10.  For fast [re: Athlon] should be 25 - 50 or so
  10  */
  11 #define TIMES (1UL<<14UL)
  12
  13 /* RDTSC from Scott Duplichan */
  14 static ulong64 TIMFUNC (void)
  15    {
  16    #if defined __GNUC__
  17       #if defined(__i386__) || defined(__x86_64__)
  18          unsigned long long a;
  19          __asm__ __volatile__ ("rdtsc\nmovl %%eax,%0\nmovl %%edx,4+%0\n"::"m"(a):"%eax","%edx");
  20          return a;
  21       #else /* gcc-IA64 version */
  22          unsigned long result;
  23          __asm__ __volatile__("mov %0=ar.itc" : "=r"(result) :: "memory");
  24          while (__builtin_expect ((int) result == -1, 0))
  25          __asm__ __volatile__("mov %0=ar.itc" : "=r"(result) :: "memory");
  26          return result;
  27       #endif
  28
  29    // Microsoft and Intel Windows compilers
  30    #elif defined _M_IX86
  31      __asm rdtsc
  32    #elif defined _M_AMD64
  33      return __rdtsc ();
  34    #elif defined _M_IA64
  35      #if defined __INTEL_COMPILER
  36        #include <ia64intrin.h>
  37      #endif
  38       return __getReg (3116);
  39    #else
  40      #error need rdtsc function for this build
  41    #endif
  42    }
  43
  44
  45 #ifndef X86_TIMER
  46
  47 /* generic ISO C timer */
  48 ulong64 LBL_T;
  49 void t_start(void) { LBL_T = TIMFUNC(); }
  50 ulong64 t_read(void) { return TIMFUNC() - LBL_T; }
  51
  52 #else
  53 extern void t_start(void);
  54 extern ulong64 t_read(void);
  55 #endif
  56
  57 ulong64 time_mult(int size, int s)
  58 {
  59   unsigned long     x;
  60   mp_int  a, b, c;
  61   ulong64 t1;
  62
  63   mp_init (&a);
  64   mp_init (&b);
  65   mp_init (&c);
  66
  67   mp_rand (&a, size);
  68   mp_rand (&b, size);
  69
  70   if (s == 1) {
  71       KARATSUBA_MUL_CUTOFF = size;
  72   } else {
  73       KARATSUBA_MUL_CUTOFF = 100000;
  74   }
  75
  76   t_start();
  77   for (x = 0; x < TIMES; x++) {
  78       mp_mul(&a,&b,&c);
  79   }
  80   t1 = t_read();
  81   mp_clear (&a);
  82   mp_clear (&b);
  83   mp_clear (&c);
  84   return t1;
  85 }
  86
  87 ulong64 time_sqr(int size, int s)
  88 {
  89   unsigned long     x;
  90   mp_int  a, b;
  91   ulong64 t1;
  92
  93   mp_init (&a);
  94   mp_init (&b);
  95
  96   mp_rand (&a, size);
  97
  98   if (s == 1) {
  99       KARATSUBA_SQR_CUTOFF = size;
 100   } else {
 101       KARATSUBA_SQR_CUTOFF = 100000;
 102   }
 103
 104   t_start();
 105   for (x = 0; x < TIMES; x++) {
 106       mp_sqr(&a,&b);
 107   }
 108   t1 = t_read();
 109   mp_clear (&a);
 110   mp_clear (&b);
 111   return t1;
 112 }
 113
 114 int
 115 main (void)
 116 {
 117   ulong64 t1, t2;
 118   int x, y;
 119
 120   for (x = 8; ; x += 2) {
 121      t1 = time_mult(x, 0);
 122      t2 = time_mult(x, 1);
 123      printf("%d: %9llu %9llu, %9llu\n", x, t1, t2, t2 - t1);
 124      if (t2 < t1) break;
 125   }
 126   y = x;
 127
 128   for (x = 8; ; x += 2) {
 129      t1 = time_sqr(x, 0);
 130      t2 = time_sqr(x, 1);
 131      printf("%d: %9llu %9llu, %9llu\n", x, t1, t2, t2 - t1);
 132      if (t2 < t1) break;
 133   }
 134   printf("KARATSUBA_MUL_CUTOFF = %d\n", y);
 135   printf("KARATSUBA_SQR_CUTOFF = %d\n", x);
 136
 137   return 0;
 138 }
 139
 140 /* $Source: /cvs/libtom/libtommath/etc/tune.c,v $ */
 141 /* $Revision: 1.3 $ */
 142 /* $Date: 2006/03/31 14:18:47 $ */