mdw@git.distorted.org.uk Git - mLib/blob - test/example/adhoc.c

   1 /* -*-c-*-
   2  *
   3  * Demonstration of ad-doc testing
   4  *
   5  * (c) 2024 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of the mLib utilities library.
  11  *
  12  * mLib is free software: you can redistribute it and/or modify it under
  13  * the terms of the GNU Library General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or (at
  15  * your option) any later version.
  16  *
  17  * mLib is distributed in the hope that it will be useful, but WITHOUT
  18  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  19  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
  20  * License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License along with mLib.  If not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  25  * USA.
  26  */
  27
  28 /*----- Header files ------------------------------------------------------*/
  29
  30 #include <limits.h>
  31 #include <stdio.h>
  32
  33 #include "macros.h"
  34 #include "report.h"
  35 #include "tvec.h"
  36 #include "tvec-adhoc.h"
  37 #include "tvec-bench.h"
  38 #include "tvec-types.h"
  39
  40 /*----- Main code ---------------------------------------------------------*/
  41
  42 /* Stupid but traditional recursive Fibonacci. */
  43 static unsigned long recfib(unsigned n)
  44   { return (n <= 1 ? n : recfib(n - 1) + recfib(n - 2)); }
  45
  46 /* Slightly less stupid but still traditional iterative Fibonacci. */
  47 static unsigned long iterfib(unsigned n)
  48 {
  49   unsigned long u, v, t;
  50
  51   for (u = 0, v = 1; n--; t = v, v = u, u += t);
  52   return (u);
  53 }
  54
  55 /* Sadly nontraditional intelligent Fibonacci. */
  56 static unsigned long expfib(unsigned n)
  57 {
  58   unsigned long a, b, u, v, t;
  59
  60   /* We work in %$\Q(\phi)$%, where %$\phi^2 = \phi + 1$%.  I claim that
  61    * %$\phi^k = F_k \phi + F_{k-1} \pmod f(\phi))$%.  Proof by induction:
  62    * note that * %$F_{-1} = F_1 - F_0 = 1$%, so %$\phi^0 = 1 = {}$%
  63    * %$F_0 \phi + F_{-1}$%; and %$\phi^{k+1} = F_k \phi^2 + {}$%
  64    * %$F_{k-1} \phi = F_k (\phi + 1) + F_{k-1} \phi = (F_k + {}$%
  65    * %$F_{k-1} \phi + F_k = F_{k+1} \phi + F_k$% as claimed.
  66    *
  67    * Now, notice that %$(a \phi + b) (c \phi + d) = a c \phi^2 + {}$%
  68    * $%(a d + b c) \phi + b d = a c (\phi + 1) + (a d + b c) \phi + {}$%
  69    * %$b d = (a c + a d + b c) \phi + (a c + b d)$%.  In particular,
  70    * %$(u \phi + v)^2 \equiv (u^2 + 2 u v) \phi + (u^2 + v^2)$%.
  71    */
  72   a = 0, b = 1; u = 1, v = 0;
  73   if (n)
  74     for (;;) {
  75       if (n%2) { t = a*u; a = t + a*v + b*u; b = t + b*v; }
  76       n /= 2; if (!n) break;
  77       t = u*u; u = t + 2*u*v; v = t + v*v;
  78     }
  79   return (a);
  80 }
  81
  82 int main(int argc, char *argv[])
  83 {
  84   struct tvec_state tvstate;
  85   int argpos;
  86   unsigned long i, a, b, t;
  87
  88   tvec_parseargs(argc, argv, &tvstate, &argpos, &tvec_adhocconfig);
  89   if (argpos < argc) die(2, "no input files expected");
  90   tvec_adhoc(&tvstate);
  91
  92 #if (ULONG_MAX/65536 >> 16) >= 0xffffffff
  93 #  define FIBLIMIT 94                /* F_94 = 19740274219868223167 > 2^64 */
  94 #else
  95 #  define FIBLIMIT 48                   /* F_48 = 4807526976 > 2^32 */
  96 #endif
  97
  98   TVEC_TESTGROUP(&tvstate, "fib-test") {
  99     for (i = 0, a = 0, b = 1; i < FIBLIMIT; i++, t = b, b = a, a += t)
 100       TVEC_TEST(&tvstate) {
 101         if (i < 40) TVEC_CLAIMEQ_UINT(&tvstate, a, recfib(i));
 102         TVEC_CLAIMEQ_UINT(&tvstate, a, iterfib(i));
 103         TVEC_CLAIMEQ_UINT(&tvstate, a, expfib(i));
 104       }
 105   }
 106
 107   TVEC_TESTGROUP(&tvstate, "fib-bench") {
 108     TVEC_BENCHMARK_DECLS;
 109
 110     if (tvec_benchprep(&tvstate, &tvec_benchstate, 0)) break;
 111
 112     TVEC_BENCHMARK("recfib, n = 40", &tvstate, tvec_benchstate, BTU_OP, 1)
 113       while (_bench_n--) ADMIRE(recfib(40));
 114     TVEC_BENCHMARK("iterfib, n = " STR(FIBLIMIT),
 115                    &tvstate, tvec_benchstate, BTU_OP, 1)
 116       while (_bench_n--) ADMIRE(iterfib(FIBLIMIT));
 117     TVEC_BENCHMARK("expfib, n = " STR(FIBLIMIT),
 118                    &tvstate, tvec_benchstate, BTU_OP, 1)
 119       while (_bench_n--) ADMIRE(expfib(FIBLIMIT));
 120   }
 121
 122   return (tvec_end(&tvstate));
 123 }
 124
 125 /*----- That's all, folks -------------------------------------------------*/