reactos/sdk/lib/crt/misc/i10output.c

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#include <precomp.h>
#define I10_OUTPUT_MAX_PREC 21
/* Internal structure used by $I10_OUTPUT */
struct _I10_OUTPUT_DATA {
short pos;
char sign;
BYTE len;
char str[I10_OUTPUT_MAX_PREC+1]; /* add space for '\0' */
};
/*********************************************************************
* $I10_OUTPUT (MSVCRT.@)
* ld80 - long double (Intel 80 bit FP in 12 bytes) to be printed to data
* prec - precision of part, we're interested in
* flag - 0 for first prec digits, 1 for fractional part
* data - data to be populated
*
* return value
* 0 if given double is NaN or INF
* 1 otherwise
*
* FIXME
* Native sets last byte of data->str to '0' or '9', I don't know what
* it means. Current implementation sets it always to '0'.
*/
int CDECL MSVCRT_I10_OUTPUT(_LDOUBLE ld80, int prec, int flag, struct _I10_OUTPUT_DATA *data)
{
static const char inf_str[] = "1#INF";
static const char nan_str[] = "1#QNAN";
/* MS' long double type wants 12 bytes for Intel's 80 bit FP format.
* Some UNIX have sizeof(long double) == 16, yet only 80 bit are used.
* Assume long double uses 80 bit FP, never seen 128 bit FP. */
long double ld = 0;
double d;
char format[8];
char buf[I10_OUTPUT_MAX_PREC+9]; /* 9 = strlen("0.e+0000") + '\0' */
char *p;
memcpy(&ld, &ld80, 10);
d = ld;
TRACE("(%lf %d %x %p)\n", d, prec, flag, data);
if(d<0) {
data->sign = '-';
d = -d;
} else
data->sign = ' ';
if(!_finite(d)) {
data->pos = 1;
data->len = 5;
memcpy(data->str, inf_str, sizeof(inf_str));
return 0;
}
if(_isnan(d)) {
data->pos = 1;
data->len = 6;
memcpy(data->str, nan_str, sizeof(nan_str));
return 0;
}
if(flag&1) {
int exp = 1+floor(log10(d));
prec += exp;
if(exp < 0)
prec--;
}
prec--;
if(prec+1 > I10_OUTPUT_MAX_PREC)
prec = I10_OUTPUT_MAX_PREC-1;
else if(prec < 0) {
d = 0.0;
prec = 0;
}
sprintf_s(format, sizeof(format), "%%.%dle", prec);
sprintf_s(buf, sizeof(buf), format, d);
buf[1] = buf[0];
data->pos = atoi(buf+prec+3);
if(buf[1] != '0')
data->pos++;
for(p = buf+prec+1; p>buf+1 && *p=='0'; p--);
data->len = p-buf;
memcpy(data->str, buf+1, data->len);
data->str[data->len] = '\0';
if(buf[1]!='0' && prec-data->len+1>0)
memcpy(data->str+data->len+1, buf+data->len+1, prec-data->len+1);
return 1;
}
#undef I10_OUTPUT_MAX_PREC