82 lines
1.6 KiB
C
82 lines
1.6 KiB
C
#include <u.h>
|
|
#include <libc.h>
|
|
|
|
/*
|
|
* Reads a floating-point number by interpreting successive characters
|
|
* returned by (*f)(vp). The last call it makes to f terminates the
|
|
* scan, so is not a character in the number. It may therefore be
|
|
* necessary to back up the input stream up one byte after calling charstod.
|
|
*/
|
|
|
|
#define ADVANCE *s++ = c; if(s>=e) return __NaN(); c = (*f)(vp)
|
|
|
|
double
|
|
charstod(int(*f)(void*), void *vp)
|
|
{
|
|
char str[400], *s, *e, *start;
|
|
int c;
|
|
|
|
s = str;
|
|
e = str + sizeof str - 1;
|
|
c = (*f)(vp);
|
|
while(c == ' ' || c == '\t')
|
|
c = (*f)(vp);
|
|
if(c == '-' || c == '+'){
|
|
ADVANCE;
|
|
}
|
|
start = s;
|
|
while(c >= '0' && c <= '9'){
|
|
ADVANCE;
|
|
}
|
|
if(c == '.'){
|
|
ADVANCE;
|
|
while(c >= '0' && c <= '9'){
|
|
ADVANCE;
|
|
}
|
|
}
|
|
if(s > start && (c == 'e' || c == 'E')){
|
|
ADVANCE;
|
|
if(c == '-' || c == '+'){
|
|
ADVANCE;
|
|
}
|
|
while(c >= '0' && c <= '9'){
|
|
ADVANCE;
|
|
}
|
|
}else if(s == start && (c == 'i' || c == 'I')){
|
|
ADVANCE;
|
|
if(c != 'n' && c != 'N')
|
|
return __NaN();
|
|
ADVANCE;
|
|
if(c != 'f' && c != 'F')
|
|
return __NaN();
|
|
ADVANCE;
|
|
if(c != 'i' && c != 'I')
|
|
return __NaN();
|
|
ADVANCE;
|
|
if(c != 'n' && c != 'N')
|
|
return __NaN();
|
|
ADVANCE;
|
|
if(c != 'i' && c != 'I')
|
|
return __NaN();
|
|
ADVANCE;
|
|
if(c != 't' && c != 'T')
|
|
return __NaN();
|
|
ADVANCE;
|
|
if(c != 'y' && c != 'Y')
|
|
return __NaN();
|
|
ADVANCE; /* so caller can back up uniformly */
|
|
USED(c);
|
|
}else if(s == str && (c == 'n' || c == 'N')){
|
|
ADVANCE;
|
|
if(c != 'a' && c != 'A')
|
|
return __NaN();
|
|
ADVANCE;
|
|
if(c != 'n' && c != 'N')
|
|
return __NaN();
|
|
ADVANCE; /* so caller can back up uniformly */
|
|
USED(c);
|
|
}
|
|
*s = 0;
|
|
return strtod(str, &s);
|
|
}
|