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- #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);
- }
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