radare2/libr/hash/luhn.c
2018-10-29 23:30:02 +01:00

21 lines
439 B
C

/* radare2 - LGPL - 2016-2018 - Copyright (C) moritz */
#include <r_hash.h>
R_API ut64 r_hash_luhn(const ut8 *buf, ut64 len) {
int curDigit, parity = (len - 1) % 2;
ut64 i, sum = 0;
char curChar[2] = {0, 0};
for (i = len; i > 0; i--) {
curChar[0] = buf[i - 1];
// ??? atoi here wtf
curDigit = atoi (curChar);
if (parity == i % 2) {
curDigit *= 2;
}
sum += curDigit / 10;
sum += curDigit % 10;
}
return sum % 10;
}