/[dtapublic]/projs/dtats/trunk/projs/2018/20180707_cgi_web_tools_aux_exe/dtats_cgi_arith_large.c
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Revision 177 - (show annotations) (download)
Tue Jul 10 01:04:10 2018 UTC (6 years ago) by dashley
Original Path: projs/dtats/trunk/projs/2018/20180707_cgi_web_tools_aux_exe/arith_large_cgi.c
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Initialize variable.
1 //$Header$
2 //********************************************************************************
3 //Copyright (c) 2003, 2018 David T. Ashley.
4 //********************************************************************************
5 //This file is part of "arith_large_cgi", a program that is designed to be
6 //invoked by a PHP script as part of serving a web page that performs
7 //calculations involving large integers. (A secondary compiled program is
8 //used because a compiled program can perform certain calculation-intensive
9 //tasks far more efficiently than a PHP script.) This program is provided by
10 //David T. Ashley (dashley@gmail.com) under the MIT License (reproduced
11 //immediately below).
12 //********************************************************************************
13 //Permission is hereby granted, free of charge, to any person obtaining a copy
14 //of this software and associated documentation files (the "Software"), to deal
15 //in the Software without restriction, including without limitation the rights
16 //to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
17 //copies of the Software, and to permit persons to whom the Software is
18 //furnished to do so, subject to the following conditions:
19 //
20 //The above copyright notice and this permission notice shall be included in all
21 //copies or substantial portions of the Software.
22 //
23 //THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
24 //IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
25 //FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
26 //AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
27 //LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
28 //OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
29 //SOFTWARE.
30 //********************************************************************************
31 //This program is written exclusively to support a PHP script which must calculate and
32 //display a number of number theory results. The necessity of this script
33 //(rather than using BCMATH) comes about because SourceForge does not have
34 //bcmath installed on its PHP system.
35 //
36 //This program is meant to be called by the PHP script using the exec()
37 //call, but could also be run by hand (and in fact this method is used for testing).
38 //
39 //The first parameter after the program name is the suboperation to be performed
40 //(each CGI page probably uses a different suboperation). This program
41 //will return a non-zero exit code only if there is a missing or unrecognized
42 //suboperation. Otherwise, error reporting is controlled by the rules of the
43 //suboperation.
44 //
45 //The currently defined suboperations are:
46 //
47 // a)"help"
48 // Display information about what the program is and how to use
49 // it.
50 // b)"gcd"
51 // Calculate the gcd of two integers using Euclid's classic
52 // algorithm and also display the intermediate results.
53 // c)"gmp_prob_prime"
54 // Use Miller-Rabin to determine to high certainty whther a
55 // number is prime or composite.
56 // d)"pfact_18"
57 // Attempt to factor a number of 18 decimal digits or less into
58 // component primes.
59 // e)"cfbrap"
60 // Finds the best rational approximation to a rational number subject
61 // to constraints on the denominator and numerator using continued
62 // fraction techniques.
63
64 #include <stdio.h>
65 #include <stdlib.h>
66 #include <string.h>
67
68 #include "auxfuncs.h"
69 #include "subfunc_cfbrap.h"
70 #include "subfunc_gcd.h"
71 #include "subfunc_gmp_prob_prime.h"
72 #include "subfunc_pfact_18.h"
73
74 //Single function prototype needed for a forward reference.
75 static void dump_subfunction_choices(int indent);
76
77 //Implements the help.
78 int SUBFUNC_HELP_main(int argc, char *argv[])
79 {
80 int i;
81 char *help[] =
82 {
83 "This program is a compiled 'C'-language program designed to be called from a",
84 "PHP script to assist in calculating number theory and large integer",
85 "arithmetic results. This scheme (of having a separate executable like this",
86 "one) was used with SourceForge web content because SourceForge did not have",
87 "the bcmath library compiled into PHP, and it was determined experimentally",
88 "that writing large integer arithmetic functions in PHP directly resulted in",
89 "unusably slow performance. This program makes use of the GMP library, which",
90 "gives it superior performance.",
91 "",
92 "This program can of course be invoked from a shell or from another scripting",
93 "language besides PHP. It is designed, however, for execution from a",
94 "scripting language, as you might guess from the human-unfriendly output.",
95 "",
96 "Please contact Dave Ashley (dtashley@aol.com) with any questions or",
97 "concerns.",
98 "",
99 "Dave Ashley, Detroit, Michigan, USA, April, 2003.",
100 "",
101 "The available subfunction choices (the first parameter on the command",
102 "line) are:",
103 };
104
105 for (i=0; i<sizeof(help)/sizeof(help[0]); i++)
106 printf("%s\n", help[i]);
107 dump_subfunction_choices(3);
108 }
109
110 //Structure type used to hold the jump table of different functions
111 //to handle different subcommands.
112 struct struct_ARITH_LARGE_CGI_subcmd_jmp
113 {
114 char *subfunc_string;
115 int (*subfunc_ptr)(int argc, char *argv[]);
116 };
117
118 //The jump table. The last element is defined to have both a
119 //NULL string pointer and a NULL function pointer.
120 static struct struct_ARITH_LARGE_CGI_subcmd_jmp subcmd_jump_tbl[] =
121 {
122 {"cfbrap", SUBFUNC_CFBRAP_main },
123 {"gcd", SUBFUNC_GCD_main },
124 {"gmp_prob_prime", SUBFUNC_GMP_PROB_PRIME_main },
125 {"pfact_18", SUBFUNC_PFACT_18_main },
126 {"help", SUBFUNC_HELP_main },
127 {NULL, NULL }
128 };
129
130 //Dumps the available choices for the subfunction code to the
131 //standard output, each indented by "indent" characters.
132 static void dump_subfunction_choices(int indent)
133 {
134 int i, j;
135
136 for (i=0; subcmd_jump_tbl[i].subfunc_string != NULL; i++)
137 {
138 for (j=0; j<indent; j++)
139 printf(" ");
140 printf("%s\n", subcmd_jump_tbl[i].subfunc_string);
141 }
142 }
143
144
145 int main(int argc, char *argv[])
146 {
147 int i;
148 int rv = 0;
149
150 if (argc < 2)
151 {
152 printf("Missing subfunction code. Choices are:\n");
153 dump_subfunction_choices(3);
154 exit(4);
155 }
156
157 for (i=0; subcmd_jump_tbl[i].subfunc_string != NULL; i++)
158 {
159 if (!strcmp(argv[1], subcmd_jump_tbl[i].subfunc_string))
160 {
161 rv = (subcmd_jump_tbl[i].subfunc_ptr)(argc, argv);
162 goto normal_return;
163 }
164 }
165
166 printf("Invalid subfunction code. Choices are:\n");
167 dump_subfunction_choices(3);
168 exit(4);
169
170 normal_return:
171 exit(rv);
172 }
173
174 //********************************************************************************
175 //End of file ARITH_LARGE_CGI.C.
176 //********************************************************************************

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