# c code
void daxpy(size_t n, double a, const double x[], double y[])
{
for (size_t i = 0; i < n; i++) {
y[i] = a*x[i] + y[i];
}
}
# SV Version
# a0 is n, a1 is ptr to x[0], a2 is ptr to y[0], fa0 is a (scalar)
VBLK.REG[0] = {type: F, isvec: 1, regkey: a3, regidx: a3, elwidth: dflt}
VBLK.REG[1] = {type: F, isvec: 1, regkey: a7, regidx: a7, elwidth: dflt}
loop:
VBLK.SETVL t0, a0, #4 # MVL=4, vl = t0 = min(a0, MVL))
c.ld a3, a1 # load 4 registers a3-6 from x
c.slli t1, t0, 3 # t1 = vl * 8 (in bytes: FP is double)
c.ld a7, a2 # load 4 registers a7-10 from y
c.add a1, a1, t1 # increment pointer to x by vl*8
fmadd a7, a3, fa0, a7 # v1 += v0 * fa0 (y = a * x + y)
c.sub a0, a0, t0 # n -= vl (t0)
c.st a7, a2 # store 4 registers a7-10 to y
c.add a2, a2, t1 # increment pointer to y by vl*8
c.bnez a0, loop # repeat if n != 0
c.ret # return
# RVV version
# a0 is n, a1 is pointer to x[0], a2 is pointer to y[0], fa0 is a
li t0, 2<<25
vsetdcfg t0 # enable 2 64b Fl.Pt. registers
loop:
setvl t0, a0 # vl = t0 = min(mvl, n)
vld v0, a1 # load vector x
c.slli t1, t0, 3 # t1 = vl * 8 (in bytes)
vld v1, a2 # load vector y
c.add a1, a1, t1 # increment pointer to x by vl*8
vfmadd v1, v0, fa0, v1 # v1 += v0 * fa0 (y = a * x + y)
c.sub a0, a0, t0 # n -= vl (t0)
vst v1, a2 # store Y
c.add a2, a2, t1 # increment pointer to y by vl*8
c.bnez a0, loop # repeat if n != 0
c.ret # return