mirror of
https://github.com/SEPPDROID/Digital-Research-Source-Code.git
synced 2025-10-23 08:24:18 +00:00
107 lines
2.5 KiB
C
107 lines
2.5 KiB
C
/*
|
||
Copyright 1982
|
||
Alcyon Corporation
|
||
8716 Production Ave.
|
||
San Diego, Ca. 92121
|
||
*/
|
||
|
||
/*char *version "@(#) atof - dec 29, 1982"; */
|
||
|
||
/*
|
||
* Ascii String to FFP Floating Point Routine :
|
||
* FFP Standard Single Precision Representation Floating Point
|
||
*
|
||
* float
|
||
* atof(buf)
|
||
* char *buf;
|
||
*
|
||
* No more than 9 significant digits are allowed in single precision.
|
||
* Largest positive number is 3.4 * 10^18 and the smallest positive
|
||
* number is 1.2 * 10^-20.
|
||
* Rely's on the fact that a long and a float are both 32 bits.
|
||
*/
|
||
|
||
#define EXPSIZ 4
|
||
#define FRACSIZ 20
|
||
|
||
long fptoffp();
|
||
float strbin();
|
||
float power10();
|
||
|
||
long
|
||
atof(buf)
|
||
char *buf;
|
||
{
|
||
char ibuf[FRACSIZ], ebuf[EXPSIZ];
|
||
register char *ip, *ep;
|
||
long ffp;
|
||
int dp, esign, isign, ebin, places;
|
||
float ibin, fp;
|
||
|
||
ip = ibuf; ep = ebuf; dp = 0; places = 0L;
|
||
while (*buf == ' ' || *buf == '\t') /* ignore white spaces */
|
||
buf++;
|
||
isign = (*buf == '-');
|
||
if (*buf == '-' || *buf == '+')
|
||
buf++;
|
||
while (*buf && *buf != 'e' && *buf != 'E') {
|
||
if (*buf == '.')
|
||
dp++;
|
||
else { /* digit seen */
|
||
*ip++ = *buf;
|
||
if (dp)
|
||
places++;
|
||
}
|
||
buf++;
|
||
}
|
||
*ip = 0;
|
||
if (*buf == 'e' || *buf == 'E') { /* exponent string */
|
||
buf++;
|
||
esign = (*buf == '-');
|
||
if (*buf == '-' || *buf == '+')
|
||
buf++;
|
||
while (*buf) /* get exponent string */
|
||
*ep++ = *buf++;
|
||
}
|
||
*ep = 0;
|
||
ibin = strbin(ibuf);
|
||
ebin = atoi(ebuf);
|
||
places = (esign) ? -ebin - places : ebin - places;
|
||
fp = ibin * power10(places);
|
||
ffp = fptoffp(fp);
|
||
if (isign) /* negative float */
|
||
ffp |= 0x80;
|
||
return( ffp );
|
||
}
|
||
|
||
float
|
||
power10(pwr) /* 10^pwr */
|
||
int pwr;
|
||
{
|
||
float f;
|
||
|
||
if (pwr < 0) /* negative power */
|
||
for (f = 1.0; pwr < 0; pwr++)
|
||
f = f / 10.0;
|
||
else /* positive power */
|
||
for (f = 1.0; pwr > 0; pwr--)
|
||
f = f * 10.0;
|
||
return(f);
|
||
}
|
||
|
||
float
|
||
strbin(p) /* decimal string => binary long */
|
||
char *p;
|
||
{
|
||
float f;
|
||
|
||
for (f = 0.0; *p >= '0' && *p <= '9'; p++) {
|
||
f = f * 10.0;
|
||
f = f + (*p - '0');
|
||
}
|
||
return(f);
|
||
}
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|