diff options
Diffstat (limited to 'builtin.c')
| -rw-r--r-- | builtin.c | 129 |
1 files changed, 128 insertions, 1 deletions
@@ -2412,6 +2412,8 @@ static char *const state = (char *const) istate; NODE * do_rand(int nargs ATTRIBUTE_UNUSED) { + double tmprand; +#define RAND_DIVISOR ((double)GAWK_RANDOM_MAX+1.0) if (firstrand) { (void) initstate((unsigned) 1, state, SIZEOF_STATE); /* don't need to srandom(1), initstate() does it for us. */ @@ -2423,7 +2425,66 @@ do_rand(int nargs ATTRIBUTE_UNUSED) * * 0 <= n < 1 */ - return make_number((AWKNUM) (random() % GAWK_RANDOM_MAX) / GAWK_RANDOM_MAX); + /* + * Date: Wed, 28 Aug 2013 17:52:46 -0700 + * From: Bob Jewett <jewett@bill.scs.agilent.com> + * + * Call random() twice to fill in more bits in the value + * of the double. Also, there is a bug in random() such + * that when the values of successive values are combined + * like (rand1*rand2)^2, (rand3*rand4)^2, ... the + * resulting time series is not white noise. The + * following also seems to fix that bug. + * + * The add/subtract 0.5 keeps small bits from filling + * below 2^-53 in the double, not that anyone should be + * looking down there. + * + * Date: Wed, 25 Sep 2013 10:45:38 -0600 (MDT) + * From: "Nelson H. F. Beebe" <beebe@math.utah.edu> + * (4) The code is typical of many published fragments for converting + * from integer to floating-point, and I discuss the serious pitfalls + * in my book, because it leads to platform-dependent behavior at the + * end points of the interval [0,1] + * + * (5) the documentation in the gawk info node says + * + * `rand()' + * Return a random number. The values of `rand()' are uniformly + * distributed between zero and one. The value could be zero but is + * never one.(1) + * + * The division by RAND_DIVISOR may not guarantee that 1.0 is never + * returned: the programmer forgot the platform-dependent issue of + * rounding. + * + * For points 4 and 5, the safe way is a loop: + * + * double + * rand(void) // return value in [0.0, 1.0) + * { + * value = internal_rand(); + * + * while (value == 1.0) + * value = internal_rand(); + * + * return (value); + * } + */ + + do { + long d1, d2; + /* + * Do the calls in predictable order to avoid + * compiler differences in order of evaluation. + */ + d1 = random(); + d2 = random(); + tmprand = 0.5 + ( (d1/RAND_DIVISOR + d2) / RAND_DIVISOR ); + tmprand -= 0.5; + } while (tmprand == 1.0); + + return make_number((AWKNUM) tmprand); } /* do_srand --- seed the random number generator */ @@ -3572,6 +3633,72 @@ do_bindtextdomain(int nargs) return make_string(the_result, strlen(the_result)); } +/* do_div --- do integer division, return quotient and remainder in dest array */ + +/* + * We define the semantics as: + * numerator = int(numerator) + * denominator = int(denonmator) + * quotient = int(numerator / denomator) + * remainder = int(numerator % denomator) + */ + +NODE * +do_div(int nargs) +{ + NODE *numerator, *denominator, *result; + double num, denom, quotient, remainder; + NODE *sub, **lhs; + + result = POP_PARAM(); + if (result->type != Node_var_array) + fatal(_("div: third argument is not an array")); + assoc_clear(result); + + denominator = POP_SCALAR(); + numerator = POP_SCALAR(); + + if (do_lint) { + if ((numerator->flags & (NUMCUR|NUMBER)) == 0) + lintwarn(_("div: received non-numeric first argument")); + if ((denominator->flags & (NUMCUR|NUMBER)) == 0) + lintwarn(_("div: received non-numeric second argument")); + } + + (void) force_number(numerator); + (void) force_number(denominator); + num = double_to_int(get_number_d(numerator)); + denom = double_to_int(get_number_d(denominator)); + + if (denom == 0.0) + fatal(_("div: division by zero attempted")); + + quotient = double_to_int(num / denom); + /* + * FIXME: This code is duplicated, factor it out to a + * separate function. + */ +#ifdef HAVE_FMOD + remainder = fmod(num, denom); +#else /* ! HAVE_FMOD */ + (void) modf(num / denom, & remainder); + remainder = num - remainder * denom; +#endif /* ! HAVE_FMOD */ + remainder = double_to_int(remainder); + + sub = make_string("quotient", 8); + lhs = assoc_lookup(result, sub); + unref(*lhs); + *lhs = make_number((AWKNUM) quotient); + + sub = make_string("remainder", 9); + lhs = assoc_lookup(result, sub); + unref(*lhs); + *lhs = make_number((AWKNUM) remainder); + + return make_number((AWKNUM) 0.0); +} + /* mbc_byte_count --- return number of bytes for corresponding numchars multibyte characters */ |