diff options
Diffstat (limited to 'numeric.c')
| -rw-r--r-- | numeric.c | 59 |
1 files changed, 59 insertions, 0 deletions
@@ -5128,6 +5128,64 @@ int_truncate(int argc, VALUE* argv, VALUE num) return rb_int_truncate(num, ndigits); } +#define DEFINE_INT_SQRT(rettype, prefix, argtype) \ +rettype \ +prefix##_isqrt(argtype n) \ +{ \ + if (sizeof(n) * CHAR_BIT > DBL_MANT_DIG && \ + n >= ((argtype)1UL << DBL_MANT_DIG)) { \ + unsigned int b = bit_length(n); \ + argtype t; \ + rettype x = (rettype)(n >> (b/2+1)); \ + x |= ((rettype)1LU << (b-1)/2); \ + while ((t = n/x) < (argtype)x) x = (rettype)((x + t) >> 1); \ + return x; \ + } \ + return (rettype)sqrt((double)n); \ +} + +DEFINE_INT_SQRT(unsigned long, rb_ulong, unsigned long) +#if SIZEOF_BDIGIT*2 > SIZEOF_LONG +DEFINE_INT_SQRT(BDIGIT, rb_bdigit_dbl, BDIGIT_DBL) +#endif + +#define domain_error(msg) \ + rb_raise(rb_eMathDomainError, "Numerical argument is out of domain - " #msg) + +VALUE rb_big_isqrt(VALUE); + +static VALUE +rb_int_s_isqrt(VALUE self, VALUE num) +{ + unsigned long n, sq; + if (FIXNUM_P(num)) { + if (FIXNUM_NEGATIVE_P(num)) { + domain_error("isqrt"); + } + n = FIX2ULONG(num); + sq = rb_ulong_isqrt(n); + return LONG2FIX(sq); + } + if (RB_TYPE_P(num, T_BIGNUM)) { + size_t biglen; + if (RBIGNUM_NEGATIVE_P(num)) { + domain_error("isqrt"); + } + biglen = BIGNUM_LEN(num); + if (biglen == 0) return INT2FIX(0); +#if SIZEOF_BDIGIT <= SIZEOF_LONG + /* short-circuit */ + if (biglen == 1) { + n = BIGNUM_DIGITS(num)[0]; + sq = rb_ulong_isqrt(n); + return ULONG2NUM(sq); + } +#endif + return rb_big_isqrt(num); + } + return Qnil; +} + /* * Document-class: ZeroDivisionError * @@ -5281,6 +5339,7 @@ Init_Numeric(void) rb_cInteger = rb_define_class("Integer", rb_cNumeric); rb_undef_alloc_func(rb_cInteger); rb_undef_method(CLASS_OF(rb_cInteger), "new"); + rb_define_singleton_method(rb_cInteger, "sqrt", rb_int_s_isqrt, 1); rb_define_method(rb_cInteger, "to_s", int_to_s, -1); rb_define_alias(rb_cInteger, "inspect", "to_s"); |