ref: c8b187f9db503465460d8bafa2d7a758bbcf59ca
dir: /lib9/charstod.c/
#include "lib9.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); }