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* util.c (ruby_strtod): try to reduce errors using powersOf10

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table.  [ruby-dev:28644]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@10160 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
matz 2006-05-16 23:24:08 +00:00
parent c606447c00
commit 7b724e750f
2 changed files with 36 additions and 21 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
Wed May 17 08:17:15 2006 Yukihiro Matsumoto <matz@ruby-lang.org>
* util.c (ruby_strtod): try to reduce errors using powersOf10
table. [ruby-dev:28644]
Tue May 16 15:34:18 2006 Yukihiro Matsumoto <matz@ruby-lang.org>
* re.c (rb_reg_initialize): should not allow modifying literal

36
util.c
View file

@ -684,6 +684,18 @@ ruby_getcwd()
#define MDMINEXPT DBL_MIN_EXP
#define MDMAXEXPT DBL_MAX_EXP
static double powersOf10[] = { /* Table giving binary powers of 10. Entry */
10.0, /* is 10^2^i. Used to convert decimal */
100.0, /* exponents into floating-point numbers. */
1.0e4,
1.0e8,
1.0e16,
1.0e32,
1.0e64,
1.0e128,
1.0e256
};
/*
*----------------------------------------------------------------------
*
@ -724,7 +736,7 @@ ruby_strtod(string, endPtr)
* address here. */
{
int sign, expSign = Qfalse;
double fraction = 0.0, dblExp;
double fraction = 0.0, dblExp, *d;
register const char *p;
register int c;
int exp = 0; /* Exponent read from "EX" field. */
@ -891,19 +903,18 @@ ruby_strtod(string, endPtr)
else {
expSign = Qfalse;
}
dblExp = 10.0;
while (exp) {
dblExp = 1.0;
for (d = powersOf10; exp != 0; exp >>= 1, d += 1) {
if (exp & 01) {
dblExp *= *d;
}
}
if (expSign) {
frac1 /= dblExp;
}
else {
frac1 *= dblExp;
}
}
exp >>= 1;
dblExp *= dblExp;
}
exp = fracExp;
if (exp < 0) {
expSign = Qtrue;
@ -912,19 +923,18 @@ ruby_strtod(string, endPtr)
else {
expSign = Qfalse;
}
dblExp = 10.0;
while (exp) {
dblExp = 1.0;
for (d = powersOf10; exp != 0; exp >>= 1, d += 1) {
if (exp & 01) {
dblExp *= *d;
}
}
if (expSign) {
frac2 /= dblExp;
}
else {
frac2 *= dblExp;
}
}
exp >>= 1;
dblExp *= dblExp;
}
fraction = frac1 + frac2;
}