On Fri, Oct 19, 2018 at 3:43 PM Bernhard Reutner-Fischer
<rep.dot....@gmail.com> wrote:
> On Fri, 19 Oct 2018 at 15:30, Bernhard Reutner-Fischer
> <rep.dot....@gmail.com> wrote:
> > On Fri, 19 Oct 2018 at 11:03, Cristian Ionescu-Idbohrn
> > <cristian.ionescu-idbo...@axis.com> wrote:
>
> Oh, an I should mention that on a 64bit box we diverge from coreutils printf:
>
> $ printf "%f\n" ' +18446744073709551614'
> 18446744073709551614.000000
> $ ./busybox printf "%f\n" ' +18446744073709551614'
> 18446744073709551616.000000
It's far worse than that:
$ ./busybox printf "%f\n" 18446744073709550592 18446744073709553665
18446744073709551616.000000
18446744073709551616.000000
64-bit double's mantissa is only 53 bits...
With "long double" shenanigans, I managed to "improve" this to:
$ ./busybox printf "%f\n" 18446744073709550592 18446744073709553665
18446744073709550591.500000
18446744073709553663.500000
at this cost:
function old new delta
printf_main 909 976 +67
strtold - 19 +19
print_direc 457 475 +18
conv_strtod 54 61 +7
------------------------------------------------------------------------------
(add/remove: 3/0 grow/shrink: 3/0 up/down: 130/0) Total: 111 bytes
See attached. Do you think it's worth it?
diff --git a/coreutils/printf.c b/coreutils/printf.c
index 67d3b2eda..215f4fef9 100644
--- a/coreutils/printf.c
+++ b/coreutils/printf.c
@@ -120,12 +120,18 @@ static void FAST_FUNC conv_strtoll(const char *arg, void *result)
static void FAST_FUNC conv_strtod(const char *arg, void *result)
{
char *end;
- /* Well, this one allows leading whitespace... so what? */
- /* What I like much less is that "-" accepted too! :( */
- *(double*)result = strtod(arg, &end);
+
+ /* If long double is no different than double, avoid using strtold() */
+ if (sizeof(double) == sizeof(long double))
+ /* Well, this one allows leading whitespace... so what? */
+ /* What I like much less is that "-" accepted too! :( */
+ *(long double*)result = strtod(arg, &end);
+ else
+ *(long double*)result = strtold(arg, &end);
+
if (end[0]) {
errno = ERANGE;
- *(double*)result = 0;
+ *(long double*)result = 0;
}
}
@@ -144,9 +150,9 @@ static long long my_xstrtoll(const char *arg)
result = 0;
return result;
}
-static double my_xstrtod(const char *arg)
+static long double my_xstrtod(const char *arg)
{
- double result;
+ long double result;
multiconvert(arg, &result, conv_strtod);
return result;
}
@@ -187,7 +193,6 @@ static void print_direc(char *format, unsigned fmt_length,
const char *argument)
{
long long llv;
- double dv;
char saved;
char *have_prec, *have_width;
@@ -255,17 +260,35 @@ static void print_direc(char *format, unsigned fmt_length,
case 'E':
case 'g':
case 'G':
- dv = my_xstrtod(argument);
- if (!have_width) {
- if (!have_prec)
- printf(format, dv);
- else
- printf(format, precision, dv);
+ if (sizeof(double) == sizeof(long double)) {
+ double dv;
+ dv = my_xstrtod(argument);
+ if (!have_width) {
+ if (!have_prec)
+ printf(format, dv);
+ else
+ printf(format, precision, dv);
+ } else {
+ if (!have_prec)
+ printf(format, field_width, dv);
+ else
+ printf(format, field_width, precision, dv);
+ }
} else {
- if (!have_prec)
- printf(format, field_width, dv);
- else
- printf(format, field_width, precision, dv);
+ /* Parsing code added "L" prefix (a-la "%Lf") */
+ long double dv;
+ dv = my_xstrtod(argument);
+ if (!have_width) {
+ if (!have_prec)
+ printf(format, dv);
+ else
+ printf(format, precision, dv);
+ } else {
+ if (!have_prec)
+ printf(format, field_width, dv);
+ else
+ printf(format, field_width, precision, dv);
+ }
}
break;
} /* switch */
@@ -371,6 +394,18 @@ static char **print_formatted(char *f, char **argv, int *conv_err)
//bb_error_msg("<%s>", p);
direc_length += 2;
direc_start = p;
+ } else
+ if (sizeof(double) < sizeof(long double)
+ && p - format_chars <= 10
+ ) {
+ /* it is one of "feEgG" */
+ p = xmalloc(direc_length + 2);
+ memcpy(p, direc_start, direc_length);
+ p[direc_length] = p[direc_length - 1];
+ p[direc_length - 1] = 'L';
+ //bb_error_msg("<%s>", p);
+ direc_length += 1;
+ direc_start = p;
} else {
p = NULL;
}
_______________________________________________
busybox mailing list
busybox@busybox.net
http://lists.busybox.net/mailman/listinfo/busybox
