On 10/26/2016 08:47 PM, David Gibson wrote:
> +void helper_vprtybq(ppc_avr_t *r, ppc_avr_t *b) > +{ > + int i; > + uint8_t s = 0; > + for (i = 0; i < 16; i++) { > + s ^= (b->u8[i] & 1); > + } > + r->u64[LO_IDX] = (!s) ? 0 : 1; > + r->u64[HI_IDX] = 0; > +} > +I think you can implement these better. First mask with 0x01010101 (of the appropriate length) to extract the LSB bits of each byte. Then XOR the two halves together, then quarters and so forth, ln2(size) times to arrive at the parity. This is similar to the usual Hamming weight implementation.
You don't even have to mask with 0x01010101 to start. Just fold halves til you get to the byte level and then mask with 1.
r~
