You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
38 lines
1.3 KiB
C
38 lines
1.3 KiB
C
#include "scan.h"
|
|
|
|
size_t scan_8longlong(const char *src,unsigned long long *dest) {
|
|
/* make a copy of src so we can return the number of bytes we progressed */
|
|
register const char *tmp=src;
|
|
register unsigned long long l=0;
|
|
register unsigned char c;
|
|
/* *tmp - '0' can be negative, but casting to unsigned char makes
|
|
* those cases positive and large; that means we only need one
|
|
* comparison. This trick is no longer needed on modern compilers,
|
|
* but we also want to produce good code on old compilers :) */
|
|
while ((c=(unsigned char)(*tmp-'0'))<8) {
|
|
/* overflow check; for each digit we multiply by 8 and then add the
|
|
* digit; 0-7 needs 3 bits of storage, so we need to check if the
|
|
* uppermost 3 bits of l are empty. Do it by shifting to the right */
|
|
if (l>>(sizeof(l)*8-3)) break;
|
|
l=l*8+c;
|
|
++tmp;
|
|
}
|
|
*dest=l;
|
|
return (size_t)(tmp-src);
|
|
}
|
|
|
|
#ifdef UNITTEST
|
|
#include <assert.h>
|
|
|
|
int main() {
|
|
unsigned long long i;
|
|
assert(scan_8longlong("1234",&i)==4 && i==01234);
|
|
assert(scan_8longlong("12345678",&i)==7 && i==01234567);
|
|
assert(scan_8longlong("1777777777777777777777",&i)==22 && i==0xffffffffffffffffull);
|
|
assert(scan_8longlong("2000000000000000000000",&i)==21 && i==0200000000000000000000ull);
|
|
assert(scan_8longlong("-4",&i)==0 && i==0);
|
|
assert(scan_8longlong("01234",&i)==5 && i==01234);
|
|
return 0;
|
|
}
|
|
#endif
|