ADSP MAC Operation Query...

[rajhere]

Hi all,

I am working on adsp 2181 processor which is a 16 bit fixed bit point processor,

Now that to perform a MAC(mULTIPLY Accumlate Operation ) there are 4 diiferent type of modes.

1) Mulitply_Integer_Add_Integer(i.e. multiplying 2 operands in fixed integer And adding Result with another operand which is also in fixed point integer fromat).

Similarly we have other modes:-

2) Multiply_Integer_Add_Fract,

3) Multiply_Fract_Add_Integer,

4)Multiply_Fract_Add_Fract,


when performing the above MAC operation for these 4 different modes...

i get different results..





One example for all these operations is shown below

MX0 = 0x0019H(25d),
MY0=0x002EH(46d),

AX0=0x0024H(36d),



multiply Operation:-

MR= MXO*MY0


Fixed point Integer mode Res=047EH; by setting MXSTAT REG=0x0010h

Fixed point Fractional Mode Res=08FCH; by resetting MXSTAT REG=0x0000h



Add operation
AY0=MR

AR=AX0+AY0

AX0=0x0024H(36d),

1) Mulitply_Integer_Add_Integer
res AR=04A2H


2) Multiply_Integer_Add_Fract
Res AR=04A2H

3) Multiply_Fract_Add_Integer
Res AR=091FH

4)Multiply_Fract_Add_Fract
Res AR=091FH



My doubt is how to validate these results...?

Which mode is to be used for real time application?