Radix-10 Multiplier

[Altera_Forum]

Hello there 

 I am looking for a shift and add style Radix-10 multiplier for Quartus II.  Does anyone have some coding I could use to make some comparisons, it doesn't have to go at 100mph, I just need to make some aspect ratio comparisons.   Thanks  Will

[Altera_Forum]

You cant shift BCD numbers. you cant add them either. (easily anyway). 

 Wouldnt it be best to do a BCD -> binary conversion, do the multiplication, and then convert back?

[Altera_Forum]

Yea I'd imagine that would work just fine 

 Basically I'm looking for a solution to the problem in Pirhami' 'Computer Arithmetic' problem 10.16a. It is essentially a radix-16 multiplier with a BCD input, that sounds very similar to your suggestion. It only has to be 16 x 16 bit multiplication.

[Altera_Forum]

a 16x16 multiplaction will take just a single multiplier, with the additional logic for the BCD conversion. Not very expensive.

[Altera_Forum]

As Tricky suggested, you need to do a BCD->binary conversion.

[Altera_Forum]

--- Quote Start ---  You cant shift BCD numbers. you cant add them either. (easily anyway).  Wouldnt it be best to do a BCD -> binary conversion, do the multiplication, and then convert back?  --- Quote End ---    You can shift BCD numbers, but only by '4' bits at a time, which comes down by multiplying by 10 - decimal that is :) I think that going from BCD to binary and back, is a bit cheating? I peeked into the exercise (via the 'look inside' function on Amazon ...). Interesting book, but pricey :( Just for the fun of doing it in BCD: you can do long multiplication per BCD digit as you would do per bit in standard binary. The adders would have to be BCD-capable, working with blocks of 4 binary bits and with appropriate carry-rules. I'm not sure that the effort in converting from BCD to Binary and back to BCD would take less resources, or be any faster?