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Contents
# A simple ALU
system :alu do
[4].input :opr
[16].input :x,:y
[16].output :s
output :zf, :cf, :sf, :vf
# The only adder instance.
instance :add do
[16].input :x,:y
input :cin
[17].output :s
s <= x+y+cin
end
# The control part for choosing between 0, add, sub and neg.
par do
# The main computation: s and cf
# Default connections
cf <= 0
vf <= 0
add.(0,0,0)
# Depending on the operator
hcase(opr)
hwhen(1) { s <= x }
hwhen(2) { s <= y }
hwhen(3) { add.(x ,y ,0,[cf,s])
vf <= (~x[15] & ~y[15] & s[15]) | (x[15] & y[15] & ~s[15]) }
hwhen(4) { add.(x ,~y,1,[cf,s])
vf <= (~x[15] & y[15] & s[15]) | (x[15] & ~y[15] & ~s[15]) }
hwhen(5) { add.(0 ,~y,1,[cf,s])
vf <= (~y[15] & s[15]) }
hwhen(6) { add.(~x,0 ,1,[cf,s])
vf <= (x[15] & ~s[15]) }
hwhen(7) { s <= x & y }
hwhen(8) { s <= x | y }
hwhen(9) { s <= x ^ y }
hwhen(10){ s <= ~x }
hwhen(11){ s <= ~y }
helse { s <= 0 }
# The remaining flags.
zf <= (s == 0)
sf <= s[15]
end
end
Version data entries
100 entries across 100 versions & 1 rubygems