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* marshal.c (w_float): append least mantissa bits to get rid

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of roundoff problem.  [ruby-talk:69518]

* marshal.c (r_object0): load least mantissa bits.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@3703 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
nobu 2003-04-20 15:11:20 +00:00
parent b7e6fc019c
commit 3f0eab216f
2 changed files with 69 additions and 6 deletions
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7
ChangeLog
View file

@ -1,3 +1,10 @@
Mon Apr 21 00:11:15 2003 Nobuyoshi Nakada <nobu.nokada@softhome.net>
* marshal.c (w_float): append least mantissa bits to get rid
of roundoff problem. [ruby-talk:69518]
* marshal.c (r_object0): load least mantissa bits.
Sun Apr 20 23:24:25 2003 WATANABE Hirofumi <eban@ruby-lang.org>
* win32/win32.c (NtInitialize): set the floating-point control word

68
marshal.c
View file

@ -16,6 +16,9 @@
#include "util.h"
#include <math.h>
#ifdef HAVE_FLOAT_H
#include <float.h>
#endif
#define BITSPERSHORT (2*CHAR_BIT)
#define SHORTMASK ((1<<BITSPERSHORT)-1)
@ -55,7 +58,7 @@ shortlen(len, ds)
#define TYPE_OBJECT 'o'
#define TYPE_DATA 'd'
#define TYPE_USERDEF 'u'
#define TYPE_USRMARHAL 'U'
#define TYPE_USRMARSHAL 'U'
#define TYPE_FLOAT 'f'
#define TYPE_BIGNUM 'l'
#define TYPE_STRING '"'
@ -181,6 +184,49 @@ w_long(x, arg)
}
}
#ifdef DBL_MANT_DIG
static int
save_mantissa(d, buf)
double d;
char *buf;
{
int e, m;
m = (int)(modf(ldexp(frexp(fabs(d), &e), DBL_MANT_DIG - 16), &d) * 0x10000);
*buf++ = 0;
*buf++ = m >> 8;
*buf++ = m;
return 3;
}
static double
load_mantissa(d, buf, len)
double d;
const char *buf;
int len;
{
if (len > 0) {
int e, s = d < 0, dig = len << 3;
unsigned long m = 0;
modf(ldexp(frexp(fabs(d), &e), DBL_MANT_DIG - dig), &d);
do {m = (m << 8) | (*buf++ & 0xff);} while (--len);
d = ldexp(frexp(d + ldexp((double)m, -dig), &dig), e);
if (s) d = -d;
}
return d;
}
#else
#define load_mantissa(d, buf, len) (d)
#define save_mantissa(d, buf) 0
#endif
#ifdef DBL_DIG
#define FLOAT_DIG (DBL_DIG+1)
#else
#define FLOAT_DIG 17
#endif
static void
w_float(d, arg)
double d;
@ -200,8 +246,13 @@ w_float(d, arg)
else strcpy(buf, "0");
}
else {
int len;
/* xxx: should not use system's sprintf(3) */
sprintf(buf, "%.16g", d);
sprintf(buf, "%.*g", FLOAT_DIG, d);
len = strlen(buf);
w_bytes(buf, len + save_mantissa(d, buf + len), arg);
return;
}
w_bytes(buf, strlen(buf), arg);
}
@ -918,18 +969,23 @@ r_object0(arg, proc)
{
double d, t = 0.0;
VALUE str = r_bytes(arg);
const char *ptr = RSTRING(str)->ptr;
if (strcmp(RSTRING(str)->ptr, "nan") == 0) {
if (strcmp(ptr, "nan") == 0) {
d = t / t;
}
else if (strcmp(RSTRING(str)->ptr, "inf") == 0) {
else if (strcmp(ptr, "inf") == 0) {
d = 1.0 / t;
}
else if (strcmp(RSTRING(str)->ptr, "-inf") == 0) {
else if (strcmp(ptr, "-inf") == 0) {
d = -1.0 / t;
}
else {
d = strtod(RSTRING(str)->ptr, 0);
char *e;
d = strtod(ptr, &e);
if (!*e++) {
d = load_mantissa(d, e, RSTRING(str)->len - (e - ptr));
}
}
v = rb_float_new(d);
r_regist(v, arg);