ISE and IEEE.Fixed_pkg (fixed point math for synth?)

Feb 11, 2005 4 Replies

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Phil Tomson 21 years ago

I'm trying to use the proposed IEEE.fixed_pkg (fixed-point math package) available here:

formatting link

The simulator doesn't complain (GHDL in this case), but ISE doesn't seem to like the negative values in ranges, like:

variable exp_value_fp : ufixed( 0 downto -17);

I get this message:

ERROR:Xst:1548 - c:/phil/vhdl/svm/../csvm.vhd line 60: Negative range in type of signal is not supported.

1) does fixed_pkg work with other synthesis tools?
2) Suggestions for other alternatives to fixed_pkg that might work with ISE?

Phil

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Jezwold 21 years ago

I don't know of any synthesis tool which supports fixed or floating point at the moment. You could write your own fixed point representation which will synthesise.

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Phil Tomson 21 years ago

Actually, I was told that the ieee.fixed_pkg works with Altera, Mentor and Synplicity synthesis tools (as long as you comment out the alias statements in it). IIRC synopsys was also on the list... But ISE was missing from the list.

Phil

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Jim Lewis 21 years ago

Phil, This would be a bug in XST. It would be helpful to submit it to them as such.

Cheers, Jim

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Jim Lewis Director of Training mailto:Jim@SynthWorks.com SynthWorks Design Inc. http://www.SynthWorks.com 1-503-590-4787 Expert VHDL Training for Hardware Design and Verification ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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Phil Tomson 21 years ago

I'm using ISE 6.2i, does anyone know if it works in 6.3*?

Phil

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