[XviD-devel] Rounding

[Michael Militzer]

Hi,

> In general a shift + add seems ok using Skal's modified tables, so for
> example:

sorry, OR seems correct for the quarter->halfpel case, so it should be:
 
// Table 7-6 (K=4)  (modified)
const int SKL_MB::Rnd_Tab_76[16] = { 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,
0, 1, 1 };
// Table 7-8 (K=2)  (modified)
const int SKL_MB::Rnd_Tab_78[ 8] = { 0, 0, 1, 1, 0, 0, 0, 1  };
// Table 7-9 (K=1)  (modified)
const int SKL_MB::Rnd_Tab_79[ 4] = { 0, 1, 1, 1 };

x = (x>>3) + Rnd_Tab_76[x & 0xF]; for rounding from 16th pel -> halfpel

x = (x>>2) + Rnd_Tab_78[x & 0x7]; for rounding from 8th pel -> halfpel

x = (x>>1) | Rnd_Tab_79[x & 0x3]; for rounding from quarterpel -> halfpel

bye,
Michael