forked from Github_Repos/cvw
35 lines
897 B
ArmAsm
35 lines
897 B
ArmAsm
|
// fir.s
|
||
|
|
// mmasserfrye@hmc.edu 30 January 2022
|
||
|
|
// FIR filter
|
||
|
|
|
||
|
|
// a0 = N, a1 = M, a2 = &X, a3 = &c, a4 = &Y
|
||
|
|
|
||
|
|
.global fir
|
||
|
|
|
||
|
|
fir:
|
||
|
|
li t0, 0 # n = 0 = t0
|
||
|
|
slli t6, a0, 3 # N*8
|
||
|
|
slli t5, a1, 3 # M*8
|
||
|
|
addi t4, t5, -8 # (M-1)*8
|
||
|
|
for1:
|
||
|
|
bge t0, t6, end # exit outer for if n >= N
|
||
|
|
fmv.d.x f3, zero # sum = 0 = f3
|
||
|
|
li t2, 0 # i = 0 = t2
|
||
|
|
add t1, t4, t0 # [(M-1) + n]*8
|
||
|
|
for2:
|
||
|
|
bge t2, t5, for1end # exit inner for if i >= M
|
||
|
|
sub t3, t1, t2 # [(M-1) + n - i]*8
|
||
|
|
add t3, t3, a2 # t3 = offset + &X
|
||
|
|
fld f0, 0(t3) # X[n-i+(M-1)]
|
||
|
|
add t3, t2, a3 # t3 = offset + &c
|
||
|
|
fld f1, 0(t3) # c[i]
|
||
|
|
fmadd.d f3, f0, f1, f3 # sum += c[i]*X[n-i+(M-1)]
|
||
|
|
addi t2, t2, 8 # i++
|
||
|
|
j for2
|
||
|
|
for1end:
|
||
|
|
add t3, t0, a4 # t3 = offset + &Y
|
||
|
|
fsd f3, 0(t3) # Y[n] = sum
|
||
|
|
addi t0, t0, 8 # n++
|
||
|
|
j for1
|
||
|
|
end:
|
||
|
|
ret
|