Radix problem

You are displaying 4-bit signed integers. It sounds like what you really want is unsigned. In the Modelsim wave window, select the signal you want to display in unsigned, right click and select 'Radix' and then 'Unsigned'.

Cheers,

Dave

thanks, but what does the 'unsigned' do..?

when i click the 'unsigned' , the nuber looks right.

but i don't know what the 'unsigned clicking' makes unsigned.

what is that?

( i'm sorry. i don't use english so.. i am not good at english.)

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thanks, but what does the 'unsigned' do..?

when i click the 'unsigned' , the nuber looks right.

but i don't know what the 'unsigned clicking' makes unsigned.

what is that?

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The 4-bit signal you are looking at can be interpreted as a signed value or unsigned value. When its interpreted as a signed value, the MSB represents -2^(B-1), where B is the number of bits. For example, with B = 3-bits you get the two possible interpretations (for the same bit representation);

Unsigned
---------
111 = 7
110 = 6
101 = 5
100 = 4
011 = 3
010 = 2
001 = 1
000 = 0
Signed
---------
011 = 3
010 = 2
001 = 1
000 = 0
111 = -1 (= -4 + 3)
110 = -2 (= -4 + 2)
101 = -3 (= -4 + 1)
100 = -4  
   

Note how the MSB represents -2^(B-1) = -4 in the signed version.

You can also interpret the 4-bit values as fractional integers, where you add a decimal point. Read this wikipedia entry:

http://en.wikipedia.org/wiki/q_%28number_format%29

and this document:

http://www.ovro.caltech.edu/~dwh/correlator/pdf/esc-100paper_hawkins.pdf (http://www.ovro.caltech.edu/%7edwh/correlator/pdf/esc-100paper_hawkins.pdf)

Cheers,

Dave

i'm so really appreciate !!!

thanks! it's really helpful for me!

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i'm so really appreciate !!!

thanks! it's really helpful for me!

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You're welcome.

Cheers,

Dave