1*40ef9009SDavid du Colombier /*
2*40ef9009SDavid du Colombier * The authors of this software are Rob Pike and Ken Thompson.
3*40ef9009SDavid du Colombier * Copyright (c) 2002 by Lucent Technologies.
4*40ef9009SDavid du Colombier * Permission to use, copy, modify, and distribute this software for any
5*40ef9009SDavid du Colombier * purpose without fee is hereby granted, provided that this entire notice
6*40ef9009SDavid du Colombier * is included in all copies of any software which is or includes a copy
7*40ef9009SDavid du Colombier * or modification of this software and in all copies of the supporting
8*40ef9009SDavid du Colombier * documentation for such software.
9*40ef9009SDavid du Colombier * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
10*40ef9009SDavid du Colombier * WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
11*40ef9009SDavid du Colombier * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
12*40ef9009SDavid du Colombier * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
13*40ef9009SDavid du Colombier */
14*40ef9009SDavid du Colombier #include <stdarg.h>
15*40ef9009SDavid du Colombier #include <string.h>
16*40ef9009SDavid du Colombier #include "utf.h"
17*40ef9009SDavid du Colombier #include "fmt.h"
18*40ef9009SDavid du Colombier #include "fmtdef.h"
19*40ef9009SDavid du Colombier
20*40ef9009SDavid du Colombier /*
21*40ef9009SDavid du Colombier * this table might overflow 127-bit exponent representations.
22*40ef9009SDavid du Colombier * in that case, truncate it after 1.0e38.
23*40ef9009SDavid du Colombier * it is important to get all one can from this
24*40ef9009SDavid du Colombier * routine since it is used in atof to scale numbers.
25*40ef9009SDavid du Colombier * the presumption is that C converts fp numbers better
26*40ef9009SDavid du Colombier * than multipication of lower powers of 10.
27*40ef9009SDavid du Colombier */
28*40ef9009SDavid du Colombier
29*40ef9009SDavid du Colombier static
30*40ef9009SDavid du Colombier double tab[] =
31*40ef9009SDavid du Colombier {
32*40ef9009SDavid du Colombier 1.0e0, 1.0e1, 1.0e2, 1.0e3, 1.0e4, 1.0e5, 1.0e6, 1.0e7, 1.0e8, 1.0e9,
33*40ef9009SDavid du Colombier 1.0e10,1.0e11,1.0e12,1.0e13,1.0e14,1.0e15,1.0e16,1.0e17,1.0e18,1.0e19,
34*40ef9009SDavid du Colombier 1.0e20,1.0e21,1.0e22,1.0e23,1.0e24,1.0e25,1.0e26,1.0e27,1.0e28,1.0e29,
35*40ef9009SDavid du Colombier 1.0e30,1.0e31,1.0e32,1.0e33,1.0e34,1.0e35,1.0e36,1.0e37,1.0e38,1.0e39,
36*40ef9009SDavid du Colombier 1.0e40,1.0e41,1.0e42,1.0e43,1.0e44,1.0e45,1.0e46,1.0e47,1.0e48,1.0e49,
37*40ef9009SDavid du Colombier 1.0e50,1.0e51,1.0e52,1.0e53,1.0e54,1.0e55,1.0e56,1.0e57,1.0e58,1.0e59,
38*40ef9009SDavid du Colombier 1.0e60,1.0e61,1.0e62,1.0e63,1.0e64,1.0e65,1.0e66,1.0e67,1.0e68,1.0e69,
39*40ef9009SDavid du Colombier };
40*40ef9009SDavid du Colombier
41*40ef9009SDavid du Colombier double
__fmtpow10(int n)42*40ef9009SDavid du Colombier __fmtpow10(int n)
43*40ef9009SDavid du Colombier {
44*40ef9009SDavid du Colombier int m;
45*40ef9009SDavid du Colombier
46*40ef9009SDavid du Colombier if(n < 0) {
47*40ef9009SDavid du Colombier n = -n;
48*40ef9009SDavid du Colombier if(n < (int)(sizeof(tab)/sizeof(tab[0])))
49*40ef9009SDavid du Colombier return 1/tab[n];
50*40ef9009SDavid du Colombier m = n/2;
51*40ef9009SDavid du Colombier return __fmtpow10(-m) * __fmtpow10(m-n);
52*40ef9009SDavid du Colombier }
53*40ef9009SDavid du Colombier if(n < (int)(sizeof(tab)/sizeof(tab[0])))
54*40ef9009SDavid du Colombier return tab[n];
55*40ef9009SDavid du Colombier m = n/2;
56*40ef9009SDavid du Colombier return __fmtpow10(m) * __fmtpow10(n-m);
57*40ef9009SDavid du Colombier }
58