Encoding:

Format:

HSUB_U.df 

HSUB_U.H wd,ws,wt

HSUB_U.W wd,ws,wt

HSUB_U.D wd,ws,wt

Purpose:

Vector Unsigned Horizontal Subtract

Vector zero extend and pairwise subtract the even elements from the odd elements to double width elements

Description:

(wd[2i+1], wd[2i]) = unsigned(ws[2i+1]) - unsigned(wt[2i])

The zero-extended odd elements in vector wt are subtracted from the zero-extended even elements in vector ws producing a signed result twice the size of the input operands. The result is written to 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:

HSUB_U.H
   for i in 0 .. WRLEN/16-1
      WR[wd]16i+15..16i = hsub_u(WR[ws]16i+15..16i, WR[wt]16i+15..16i, 8)
   endfor
HSUB_U.W
   for i in 0 .. WRLEN/32-1
      WR[wd]32i+31..32i = hsub_u(WR[ws]32i+31..32i, WR[wt]32i+31..32i, 16)
   endfor
HSUB_U.D
   for i in 0 .. WRLEN/64-1
      WR[wd]64i+63..64i = hsub_u(WR[ws]64i+63..64i, WR[wt]64i+63..64i, 32)
   endfor
function hsub_u(ts, tt, n)
   t = (0n || ts2n-1..n) - (0n || ttn-1..0)
   return t
endfunction hsub_u

Exceptions:

Reserved Instruction Exception, MSA Disabled Exception.