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57 lines
1.0 KiB
C
57 lines
1.0 KiB
C
#include "scan.h"
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#ifdef __GNUC__
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static inline int isdigit(int c) { return (c>='0' && c<='9'); }
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#else
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#include <ctype.h>
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#endif
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size_t scan_double(const char *in, double *dest) {
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double d=0;
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register const char *c=in;
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char neg=0;
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switch (*c) {
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case '-': neg=1; /* fall through */
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case '+': c++; break;
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default: break;
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}
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while (isdigit(*c)) {
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d=d*10+(*c-'0');
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++c;
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}
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if (*c=='.') {
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double factor=.1;
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while (isdigit(*++c)) {
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d=d+(factor*(*c-'0'));
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factor/=10;
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}
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}
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if ((*c|32)=='e') {
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int exp=0;
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char neg=0;
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if (c[1]<'0') {
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switch (*c) {
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case '-': neg=1; /* fall through */
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case '+': c++; break;
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default:
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d=0;
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c=in;
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goto done;
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}
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}
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while (isdigit(*++c))
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exp=exp*10+(*c-'0');
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if (neg)
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while (exp) { /* XXX: this introduces rounding errors */
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d/=10; --exp;
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}
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else
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while (exp) { /* XXX: this introduces rounding errors */
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d*=10; --exp;
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}
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}
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done:
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*dest=(neg?-d:d);
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return (size_t)(c-in);
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}
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