Encoding:

Format:

DPADD_S.df 

DPADD_S.H wd,ws,wt

DPADD_S.W wd,ws,wt

DPADD_S.D wd,ws,wt

Purpose:

Vector Signed Dot Product and Add

Vector signed dot p roduct (multiply and then pairwise ad d the adjacent mu ltiplication results) and add to double width elements.

Description:

(wd[2i+1], wd[2i]) = (wd[2i+1], wd[2i]) + signed(ws[2i+1]) * 
signed(wt[2i+1]) + signed(ws[2i]) * signed(wt[2i])

The signed integer elements in vector wt are multiplied by signed integer elements in vector ws producing a result twice the size of the input operands. The multiplication results of adjacent odd/even elements are added to the integer elements in vector wd.

The operands are values in integer data format half the size of df. The results are values in integer data format df.

Restrictions:

No data-dependent exceptions are possible.

Operation:

DPADD_S.H
   for i in 0 .. WRLEN/16-1
      WR[wd]16i+15..16i = 
             WR[wd]16i+15..16i + dotp_s(WR[ws]16i+15..16i, WR[wt]16i+15..16i, 8)
   endfor
DPADD_S.W
   for i in 0 .. WRLEN/32-1
      WR[wd]32i+31..32i =
             WR[wd]32i+31..32i + dotp_s(WR[ws]32i+31..32i, WR[wt]32i+31..32i, 16)
   endfor
DPADD_S.D
   for i in 0 .. WRLEN/64-1
      WR[wd]64i+63..64i =
             WR[wd]64i+63..64i + dotp_s(WR[ws]64i+63..64i, WR[wt]64i+63..64i, 32)
   endfor
function mulx_s(ts, tt, n)
   s = (tsn-1)n || tsn-1..0 
   t = (ttn-1)n || ttn-1..0
   p = s * t 
   return p2n-1..0
endfunction mulx_s
function dotp_s(ts, tt, n)
   p1 = mulx_s(ts2n-1..n, tt2n-1..n, n)
   p0 = mulx_s(tsn-1..0, ttn-1..0, n)
   p = p1 + p0
   return p2n-1..0
endfunction dotp_s

Exceptions:

Reserved Instruction Exception, MSA Disabled Exception.