ref: ee4b58548e0df76a402c09ffcf0964d0e6cddbfa
dir: /libsec/tsmemcmp.c/
#include <u.h> #include <libc.h> #include <libsec.h> /* * timing safe memcmp() */ int tsmemcmp(void *a1, void *a2, ulong n) { int lt, gt, c1, c2, r, m; uchar *s1, *s2; r = m = 0; s1 = a1; s2 = a2; while(n--){ c1 = *s1++; c2 = *s2++; lt = (c1 - c2) >> 8; gt = (c2 - c1) >> 8; r |= (lt - gt) & ~m; m |= lt | gt; } return r; }