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41 lines
1.3 KiB
C
41 lines
1.3 KiB
C
#include "scan.h"
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/* this is cut and paste from scan_ulong instead of calling scan_ulong
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* because this way scan_ushort can abort scanning when the number would
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* not fit into an unsigned short (as opposed to not fitting in an
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* unsigned long) */
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size_t scan_ushort(const char* src,unsigned short* dest) {
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if (sizeof(unsigned short) == sizeof(unsigned int)) {
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/* a good optimizing compiler should remove the else clause when not
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* needed */
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return scan_uint(src,(unsigned int*)dest);
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} if (sizeof(unsigned short) < sizeof(unsigned long)) {
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const char* cur;
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unsigned short l;
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for (cur=src,l=0; *cur>='0' && *cur<='9'; ++cur) {
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unsigned long tmp=l*10ul+*cur-'0';
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if ((unsigned short)tmp != tmp) break;
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l=tmp;
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}
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if (cur>src) *dest=l;
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return (size_t)(cur-src);
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} else {
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register const char *tmp=src;
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register unsigned short int l=0;
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register unsigned char c;
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while ((c=(unsigned char)(*tmp-'0'))<10) {
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unsigned short int n;
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/* division is very slow on most architectures */
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n=(unsigned short)(l<<3); if ((n>>3)!=l) break;
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if ((unsigned short)(n+(l<<1)) < n) break;
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n=(unsigned short)(n+(l<<1));
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if ((unsigned short)(n+c) < n) break;
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l=(unsigned short)(n+c);
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++tmp;
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}
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if (tmp-src) *dest=l;
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return (size_t)(tmp-src);
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}
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}
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