Revision: 3698 http://trac.macosforge.org/projects/ruby/changeset/3698 Author: lsansonetti@apple.com Date: 2010-03-04 16:33:32 -0800 (Thu, 04 Mar 2010) Log Message: ----------- added #sum Modified Paths: -------------- MacRuby/branches/icu/string.c Modified: MacRuby/branches/icu/string.c =================================================================== --- MacRuby/branches/icu/string.c 2010-03-05 00:21:39 UTC (rev 3697) +++ MacRuby/branches/icu/string.c 2010-03-05 00:33:32 UTC (rev 3698) @@ -4747,6 +4747,42 @@ return str; } +/* + * call-seq: + * str.sum(n=16) => integer + * + * Returns a basic <em>n</em>-bit checksum of the characters in <i>str</i>, + * where <em>n</em> is the optional <code>Fixnum</code> parameter, defaulting + * to 16. The result is simply the sum of the binary value of each character in + * <i>str</i> modulo <code>2n - 1</code>. This is not a particularly good + * checksum. + */ + +static VALUE +rstr_sum(VALUE str, SEL sel, int argc, VALUE *argv) +{ + int bits = 16; + if (argc > 0) { + VALUE vbits; + rb_scan_args(argc, argv, "01", &vbits); + bits = NUM2INT(vbits); + } + + if (bits >= sizeof(long) * CHAR_BIT) { + rb_raise(rb_eArgError, "bits argument too big"); + } + + unsigned long sum = 0; + for (long i = 0; i < RSTR(str)->length_in_bytes; i++) { + sum += (unsigned char)RSTR(str)->data.bytes[i]; + } + if (bits != 0) { + sum &= (((unsigned long)1) << bits) - 1; + } + + return rb_int2inum(sum); +} + // NSString primitives. static void @@ -4922,6 +4958,7 @@ rb_objc_define_method(rb_cRubyString, "delete!", rstr_delete_bang, -1); rb_objc_define_method(rb_cRubyString, "squeeze", rstr_squeeze, -1); rb_objc_define_method(rb_cRubyString, "squeeze!", rstr_squeeze_bang, -1); + rb_objc_define_method(rb_cRubyString, "sum", rstr_sum, -1); // MacRuby extensions. rb_objc_define_method(rb_cRubyString, "transform", rstr_transform, 1);