Mirror of :pserver:cvs@cvs.fefe.de:/cvs libowfat https://www.fefe.de/libowfat/
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

25 lines
992 B

22 years ago
#include "scan.h"
size_t scan_8short(const char* src,unsigned short* dest) {
/* make a copy of src so we can return the number of bytes we progressed */
register const char *tmp=src;
/* this is called l because we copy and pasted from 8long, where l
* stood for "long" */
register unsigned short 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=(unsigned short)(l*8+c);
++tmp;
}
22 years ago
*dest=l;
return (size_t)(tmp-src);
22 years ago
}