Multiplying 8bit numbers using Tau interpreter

[pk(OP)]

Please see below how we can use the Tau interpreter to multiply two 8bit numbers. Of course it can be easily extended to handle more bits, the important thing to remember is to keep the input file, called here "mask.in", filled with 0s (zeros) - to be exact double the amount of the input numbers' bits. So for this 8bits demo there should be 16 rows of 0s in "mask.in" file.

Code Select Expand

# a = 213 (11010101)
a8() := 1 # MSB
a7() := 1
a6() := 0
a5() := 1
a4() := 0
a3() := 1
a2() := 0
a1() := 1 # LSB
# b = 170 (10101010)
b8() := 1 # MSB
b7() := 0
b6() := 1
b5() := 0
b4() := 1
b3() := 0
b2() := 1
b1() := 0 # LSB

r_adder() := o2[0]=i1[0]+i2[0] && o2[t]=o1[t]+i1[t]+i2[t] && o1[t]=(i1[t-1]|i2[t-1])o1[t-1] | i1[t-1]i2[t-1]
init(x8,x7,x6,x5,x4,x3,x2,x1) := o0[0]=x1 && o0[1]=x2 && o0[2]=x3 && o0[3]=x4 && o0[4]=x5 && o0[5]=x6 && o0[6]=x7 && o0[7]=x8 && o1[t]=i0[t]

sbf i0=ifile("mask.in") # For multiplying 8bit numbers the mask file should have 16 zeros.
sbf o0=ofile("n1.in")
sbf o1=ofile("tmp0.out")
r init(a8(),a7(),a6(),a5(),a4(),a3(),a2(),a1())
sbf o0=ofile("n2.in")
r init(b8(),b7(),b6(),b5(),b4(),b3(),b2(),b1())

part1(x) := (x=1) ? (o1[t]=i1[t]) : (o1[t]=i0[t])
part2(x) := (x=1) ? (o1[t]=i1[t-1]) : (o1[t]=i0[t-1])
part3(x) := (x=1) ? (o1[t]=i1[t-2]) : (o1[t]=i0[t-2])
part4(x) := (x=1) ? (o1[t]=i1[t-3]) : (o1[t]=i0[t-3])
part5(x) := (x=1) ? (o1[t]=i1[t-4]) : (o1[t]=i0[t-4])
part6(x) := (x=1) ? (o1[t]=i1[t-5]) : (o1[t]=i0[t-5])
part7(x) := (x=1) ? (o1[t]=i1[t-6]) : (o1[t]=i0[t-6])
part8(x) := (x=1) ? (o1[t]=i1[t-7]) : (o1[t]=i0[t-7])

sbf i1=ifile("n1.in")
sbf i2=ifile("n2.in")
sbf o1=ofile("part1.out")
r part1(b1())
sbf o1=ofile("part2.out")
r part2(b2())
sbf o1=ofile("part3.out")
r part3(b3())
sbf o1=ofile("part4.out")
r part4(b4())
sbf o1=ofile("part5.out")
r part5(b5())
sbf o1=ofile("part6.out")
r part6(b6())
sbf o1=ofile("part7.out")
r part7(b7())
sbf o1=ofile("part8.out")
r part8(b8())

sbf o1=ofile("carry.out")

sbf i1=ifile("part1.out")
sbf i2=ifile("part2.out")
sbf o2=ofile("tmp1.out")
r r_adder()
sbf i1=ifile("tmp1.out")
sbf i2=ifile("part3.out")
sbf o2=ofile("tmp2.out")
r r_adder()
sbf i1=ifile("tmp2.out")
sbf i2=ifile("part4.out")
sbf o2=ofile("tmp3.out")
r r_adder()
sbf i1=ifile("tmp3.out")
sbf i2=ifile("part5.out")
sbf o2=ofile("tmp4.out")
r r_adder()
sbf i1=ifile("tmp4.out")
sbf i2=ifile("part6.out")
sbf o2=ofile("tmp5.out")
r r_adder()
sbf i1=ifile("tmp5.out")
sbf i2=ifile("part7.out")
sbf o2=ofile("tmp6.out")
r r_adder()
sbf i1=ifile("tmp6.out")
sbf i2=ifile("part8.out")
sbf o2=ofile("added.out")
r r_adder()