Philippe Gerum wrote:
> static inline unsigned long long ns_2_cycles(unsigned long long ns)
> {
> return ns * ns2cyc_scale >> NS2CYC_SCALE_FACTOR;
This multiplication is 64 bits * 32 bits, the intermediate result may
need more than 64 bits, so you should compute it the same way as the
beginning of ullimd. Something like:
static inline unsigned long long ns_2_cycles(unsigned long long ns)
{
unsigned nsh, nsl, tlh, tll;
unsigned long long th, tl;
__rthal_u64tou32(ns, nsh, nsl);
tl = rthal_ullmul(nsl, ns2cyc_scale);
__rthal_u64tou32(tl, tlh, tll);
th = rthal_ullmul(nsh, ns2cyc_scale);
th += tlh;
tll = (unsigned) th << (32 - NS2CYC_SCALE_FACTOR) | tll >>
NS2CYC_SCALE_FACTOR;
th >>= NS2CYC_SCALE_FACTOR;
return __rthal_u64fromu32(th, tll);
}
--
Gilles Chanteperdrix.
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