34 lines
912 B
C
34 lines
912 B
C
#include <stddef.h>
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#include <errno.h>
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#include <stdint.h>
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/** `printf`-compatible substring. */
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struct substring { const char *sub; size_t size; };
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/** Parse unsigned; [`s`,`e`) => `n`. */
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static int helper_natural(const char *s, const char *const e, uint32_t *const n)
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{
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uint32_t accum = 0;
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while(s < e) {
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unsigned next = accum * 10 + (unsigned)(*s - '0');
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if(accum >= next) return errno = ERANGE, 0;
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accum = next;
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s++;
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}
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*n = accum;
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return 1;
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}
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/** djb2 <http://www.cse.yorku.ca/~oz/hash.html> */
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static uint32_t djb2(const char *s) {
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const unsigned char *str = (const unsigned char *)s;
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uint32_t hash = 5381, c;
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while(c = *str++) hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
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return hash;
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}
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static void unused_helper_coda(void);
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static void unused_helper(void)
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{ helper_natural(0, 0, 0); djb2(0); unused_helper_coda(); }
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static void unused_helper_coda(void) { unused_helper(); }
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