Copyright (C) 1990, 1992, Digital Equipment Corporation.     
 All rights reserved.                                         
 See the file COPYRIGHT for a full description.               
 Last modified on Tue Mar  3 18:39:13 PST 1992 by muller      
      modified on Thu Dec 21 11:40:01 1989 by kalsow          

low-level C routines for numeric conversions.

Index: conversion; numbers; ASCII


FROM Ctypes IMPORT double, int, int_star, char_star, char_star_star;

<* EXTERNAL m3_strtod *>
Returns a nearest machine number to the input decimal string (or sets errno to ERANGE). With IEEE arithmetic, ties are broken by the IEEE round-even rule. Otherwise ties are broken by biased rounding (add half and chop).

<* EXTERNAL m3_dtoa *>
PROCEDURE dtoa (d: double;  mode: int;  ndigits: int;  decpt: int_star;
                sign: int_star;  rve: char_star_star): char_star;
Converts a C double to an ASCII string.
 Arguments ndigits, decpt, sign are similar to those
   of ecvt and fcvt; trailing zeros are suppressed from
   the returned string.  If not null, *rve is set to point
   to the end of the return value.  If d is +-Infinity or NaN,
   then *decpt is set to 9999.

mode: 0 ==> shortest string that yields d when read in and rounded to nearest. 1 ==> like 0, but with Steele & White stopping rule; e.g. with IEEE P754 arithmetic , mode 0 gives 1e23 whereas mode 1 gives 9.999999999999999e22. 2 ==> max(1,ndigits) significant digits. This gives a return value similar to that of ecvt, except that trailing zeros are suppressed. 3 ==> through ndigits past the decimal point. This gives a return value similar to that from fcvt, except that trailing zeros are suppressed, and ndigits can be negative. 4,5 ==> similar to 2 and 3, respectively, but (in round-nearest mode) with the tests of mode 0 to possibly return a shorter string that rounds to d. With IEEE arithmetic and compilation with -DHonor_FLT_ROUNDS, modes 4 and 5 behave the same as modes 2 and 3 when FLT_ROUNDS != 1. 6-9 ==> Debugging modes similar to mode - 4: don't try fast floating-point estimate (if applicable).

Values of mode other than 0-9 are treated as mode 0.

Sufficient space is allocated to the return value to hold the suppressed trailing zeros.

<* EXTERNAL m3_freedtoa *>
PROCEDURE freedtoa (s: char_star);
Must be used to free values s returned by dtoa.


END CConvert.
The implementations of these routines can be found in m3core/src/Csupport/Common/dtoa.h. They are derived from David M. Gay's code distributed by AT&T.