simple_v_extension/daxpy_example.mdwn

   1     # a0 is n, a1 is ptr to x[0], a2 is ptr to y[0], fa0 is a
   2      VBLK.REG[0] = {type: F, regkey: a3, regidx: a3, elwidth: dflt}
   3      VBLK.REG[1] = {type: F, regkey: a7, regidx: a7, elwidth: dflt}
   4      VBLK.MVL = 4
   5     loop:
   6      setvl  t0, a0          # vl = t0 = min(a0, MVL))
   7      ld     a3, a1          # load 4 registers a3-6 from x
   8      slli   t1, t0, 3       # t1 = vl * 8 (in bytes)
   9      ld     a7, a2          # load 4 registers a7-10 from y
  10      add    a1, a1, t1      # increment pointer to x by vl*8
  11      fmadd  a7, a3, fa0, a7 # v1 += v0 * fa0 (y = a * x + y)
  12      sub    a0, a0, t0      # n -= vl (t0)
  13      st     a7, a2          # store 4 registers a7-10 to y
  14      add    a2, a2, t1      # increment pointer to y by vl*8
  15      bnez   a0, loop        # repeat if n != 0