Multiplier question on positive and negative values

[nemolee]

Multiplier with sign bit

Dear All,

Please give me a good advice.
The two input data may be positive value or negative value.
How should I do? If the input data of this multiplier can be negative, it can only handle positive value.

Thanks.

 

[echo47]

Multiplier with sign bit

Your question is unclear. If you want to multiply two signed values, then use a signed multiplier.

 

[omara007]

Re: Multiplier with sign bit

I guess ur worry is simple .. maybe u think that signed Multipliers only accept negative inputs , right ? ..
If this is what I understood from ur unclear message , then the answer is : Don't worry .. signed multipliers are design so as to handle all combinations of inputs :
1- Positive with Positive
2- Positive with negative
3- Negative with Negative

So, anything else ?

 

[spweda]

Re: Multiplier with sign bit

It depends what your are doing. If you design a hardware to implement the multiplier, you should consider this sign multiplication problem. However, VHDL or Virelog should handle it unless you really want to optimize the multiplier design by hand. If you use DSP to program, DSP should handle the sign multiplication. If you use fractional mode, TI DSP could left shift the result by 1 bit.

 

[claint]

Re: Multiplier with sign bit

signed multipier can handle all signed or unsigned cases,you can find such result in some computer arithmatic books.

 

[spweda]

Re: Multiplier with sign bit

It should be careful on the signed and unsigned number. For example, if 16 bits unsigned is used, 1000,0000,0000,0000 denotes 65536. However, for signed, it denotes -32768. You should not assume that the signed operation will handle unsigned operation automatically.

 

[omara007]

Re: Multiplier with sign bit

take care that if u multiply 2 signed numbers, the result will contain 2 sign bits ..

 

[suvendu]

Re: Multiplier with sign bit

first of all ur question is not clear.if u want to multiply two numbers in any assembly language ,it depends upon the processor(ie whether 8085 or 8086).
so plz resend the question with clarity.

 

[cedance]

Re: Multiplier with sign bit

take care that if u multiply 2 signed numbers, the result will contain 2 sign bits ..

what do u mean with that? really couldnt get it.

/cedance

 

[freeinthewind]

Multiplier with sign bit

u can use design method of BOOTH multiplexer. it is for multiplex of signed datas.