Ruby  2.0.0p247(2013-06-27revision41674)
ext/digest/bubblebabble/bubblebabble.c
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00001 /************************************************
00002 
00003   bubblebabble.c - BubbleBabble encoding support
00004 
00005   $Author: nobu $
00006   created at: Fri Oct 13 18:31:42 JST 2006
00007 
00008   Copyright (C) 2006 Akinori MUSHA
00009 
00010   $Id: bubblebabble.c 27437 2010-04-22 08:04:13Z nobu $
00011 
00012 ************************************************/
00013 
00014 #include "ruby.h"
00015 #include "digest.h"
00016 
00017 static ID id_digest;
00018 
00019 static VALUE
00020 bubblebabble_str_new(VALUE str_digest)
00021 {
00022     char *digest;
00023     size_t digest_len;
00024     VALUE str;
00025     char *p;
00026     size_t i, j, seed = 1;
00027     static const char vowels[] = {
00028         'a', 'e', 'i', 'o', 'u', 'y'
00029     };
00030     static const char consonants[] = {
00031         'b', 'c', 'd', 'f', 'g', 'h', 'k', 'l', 'm', 'n',
00032         'p', 'r', 's', 't', 'v', 'z', 'x'
00033     };
00034 
00035     StringValue(str_digest);
00036     digest = RSTRING_PTR(str_digest);
00037     digest_len = RSTRING_LEN(str_digest);
00038 
00039     if ((LONG_MAX - 2) / 3 < (digest_len | 1)) {
00040         rb_raise(rb_eRuntimeError, "digest string too long");
00041     }
00042 
00043     str = rb_str_new(0, (digest_len | 1) * 3 + 2);
00044     p = RSTRING_PTR(str);
00045 
00046     i = j = 0;
00047     p[j++] = 'x';
00048 
00049     for (;;) {
00050         unsigned char byte1, byte2;
00051 
00052         if (i >= digest_len) {
00053             p[j++] = vowels[seed % 6];
00054             p[j++] = consonants[16];
00055             p[j++] = vowels[seed / 6];
00056             break;
00057         }
00058 
00059         byte1 = digest[i++];
00060         p[j++] = vowels[(((byte1 >> 6) & 3) + seed) % 6];
00061         p[j++] = consonants[(byte1 >> 2) & 15];
00062         p[j++] = vowels[((byte1 & 3) + (seed / 6)) % 6];
00063 
00064         if (i >= digest_len) {
00065             break;
00066         }
00067 
00068         byte2 = digest[i++];
00069         p[j++] = consonants[(byte2 >> 4) & 15];
00070         p[j++] = '-';
00071         p[j++] = consonants[byte2 & 15];
00072 
00073         seed = (seed * 5 + byte1 * 7 + byte2) % 36;
00074     }
00075 
00076     p[j] = 'x';
00077 
00078     return str;
00079 }
00080 
00081 /*
00082  * call-seq:
00083  *     Digest.bubblebabble(string) -> bubblebabble_string
00084  *
00085  * Returns a BubbleBabble encoded version of a given _string_.
00086  */
00087 static VALUE
00088 rb_digest_s_bubblebabble(VALUE klass, VALUE str)
00089 {
00090     return bubblebabble_str_new(str);
00091 }
00092 
00093 /*
00094  * call-seq:
00095  *     Digest::Class.bubblebabble(string, ...) -> hash_string
00096  *
00097  * Returns the BubbleBabble encoded hash value of a given _string_.
00098  */
00099 static VALUE
00100 rb_digest_class_s_bubblebabble(int argc, VALUE *argv, VALUE klass)
00101 {
00102     return bubblebabble_str_new(rb_funcall2(klass, id_digest, argc, argv));
00103 }
00104 
00105 /*
00106  * call-seq:
00107  *     digest_obj.bubblebabble -> hash_string
00108  *
00109  * Returns the resulting hash value in a Bubblebabble encoded form.
00110  */
00111 static VALUE
00112 rb_digest_instance_bubblebabble(VALUE self)
00113 {
00114     return bubblebabble_str_new(rb_funcall(self, id_digest, 0));
00115 }
00116 
00117 /*
00118  * This module adds some methods to Digest classes to perform
00119  * BubbleBabble encoding.
00120  */
00121 void
00122 Init_bubblebabble(void)
00123 {
00124     VALUE mDigest, mDigest_Instance, cDigest_Class;
00125 
00126     rb_require("digest");
00127 
00128     mDigest = rb_path2class("Digest");
00129     mDigest_Instance = rb_path2class("Digest::Instance");
00130     cDigest_Class = rb_path2class("Digest::Class");
00131 
00132     /* Digest::bubblebabble() */
00133     rb_define_module_function(mDigest, "bubblebabble", rb_digest_s_bubblebabble, 1);
00134 
00135     /* Digest::Class::bubblebabble() */
00136     rb_define_singleton_method(cDigest_Class, "bubblebabble", rb_digest_class_s_bubblebabble, -1);
00137 
00138     /* Digest::Instance#bubblebabble() */
00139     rb_define_method(mDigest_Instance, "bubblebabble", rb_digest_instance_bubblebabble, 0);
00140 
00141     id_digest = rb_intern("digest");
00142 }
00143