github.com/razvanm/vanadium-go-1.3@v0.0.0-20160721203343-4a65068e5915/test/bench/shootout/pidigits.c (about)

     1  /*
     2  Redistribution and use in source and binary forms, with or without
     3  modification, are permitted provided that the following conditions are met:
     4  
     5      * Redistributions of source code must retain the above copyright
     6      notice, this list of conditions and the following disclaimer.
     7  
     8      * Redistributions in binary form must reproduce the above copyright
     9      notice, this list of conditions and the following disclaimer in the
    10      documentation and/or other materials provided with the distribution.
    11  
    12      * Neither the name of "The Computer Language Benchmarks Game" nor the
    13      name of "The Computer Language Shootout Benchmarks" nor the names of
    14      its contributors may be used to endorse or promote products derived
    15      from this software without specific prior written permission.
    16  
    17  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
    18  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    19  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    20  ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
    21  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
    22  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
    23  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
    24  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
    25  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
    26  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    27  POSSIBILITY OF SUCH DAMAGE.
    28  */
    29  
    30  /* The Computer Language Benchmarks Game
    31    http://shootout.alioth.debian.org/
    32  
    33    contributed by Paolo Bonzini & Sean Bartlett
    34    modified by Michael Mellor
    35  */
    36  
    37  #include <stdio.h>
    38  #include <stdlib.h>
    39  #include <gmp.h>
    40  
    41  static mpz_t numer, accum, denom, tmp1, tmp2;
    42  
    43  static int extract_digit()
    44  {
    45    if (mpz_cmp(numer, accum) > 0)
    46      return -1;
    47  
    48    /* Compute (numer * 3 + accum) / denom */
    49    mpz_mul_2exp(tmp1, numer, 1);
    50    mpz_add(tmp1, tmp1, numer);
    51    mpz_add(tmp1, tmp1, accum);
    52    mpz_fdiv_qr(tmp1, tmp2, tmp1, denom);
    53  
    54    /* Now, if (numer * 4 + accum) % denom... */
    55    mpz_add(tmp2, tmp2, numer);
    56  
    57    /* ... is normalized, then the two divisions have the same result.  */
    58    if (mpz_cmp(tmp2, denom) >= 0)
    59      return -1;
    60  
    61    return mpz_get_ui(tmp1);
    62  }
    63  
    64  static void next_term(unsigned int k)
    65  {
    66    unsigned int y2 = k*2 + 1;
    67  
    68    mpz_mul_2exp(tmp1, numer, 1);
    69    mpz_add(accum, accum, tmp1);
    70    mpz_mul_ui(accum, accum, y2);
    71    mpz_mul_ui(numer, numer, k);
    72    mpz_mul_ui(denom, denom, y2);
    73  }
    74  
    75  static void eliminate_digit(unsigned int d)
    76  {
    77    mpz_submul_ui(accum, denom, d);
    78    mpz_mul_ui(accum, accum, 10);
    79    mpz_mul_ui(numer, numer, 10);
    80  }
    81  
    82  static void pidigits(unsigned int n)
    83  {
    84    int d;
    85    unsigned int i = 0, k = 0, m;
    86    mpz_init(tmp1);
    87    mpz_init(tmp2);
    88    mpz_init_set_ui(numer, 1);
    89    mpz_init_set_ui(accum, 0);
    90    mpz_init_set_ui(denom, 1);
    91  
    92    for(;;)
    93    {
    94      do {
    95        k++;
    96        next_term(k);
    97        d = extract_digit();
    98      } while(d == -1);
    99  
   100      putchar(d + '0');
   101  
   102      i++;
   103      m = i%10;
   104      if(m == 0)
   105        printf("\t:%d\n", i);
   106      if(i >= n)
   107        break;
   108      eliminate_digit(d);
   109    }
   110  
   111    if(m) {
   112      m = 10 - m;
   113      while(m--)
   114        putchar(' ');
   115      printf("\t:%d\n", n);
   116    }
   117  }
   118  
   119  int main(int argc, char **argv)
   120  {
   121    pidigits(argc > 1 ? atoi(argv[1]) : 27);
   122    return 0;
   123  }