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