Forum: GHDL newbie questions

I have been using Xilinx ISE 10.1 on windows sofar but I'm running into 
some weird problems with CoolRunner and I wanted to try compiling with 
something other than Xilinx' tools.

Xilinx ISE steps are:
synthesize - xst
translate
fit
generate programming file

I'm not sure exactly where ghdl fits in.
Obviously, ghdl can compile vhd files, but at which stage do I need to 
go back to xilinx? I do understand that as one of the last steps, I 
*have* to use Xilinx utility in order to generate the .jed file and for 
actually programming the xilinx.

Terminology is a bit confusing... analyze, elaborate, run?


As a first attempt, I tried to analyze a vhd file but it failed with:
cannot find resource library "unisim"

I tried to use the -PPATH but it just won't work.

I believe the xilinx libraries are in \Xilinx\10.1\ISE\vhdl\hdp\nt 
folder which has the following subdirs:
aim, cpld, ieee ... unisim, xilinxcorelib

I tried adding the following path, but it still wouldn't find unisim:
ghdl -a --workdir=test -P\Xilinx\10.1\ISE\vhdl\hdp\nt myfile.vhd

inside the vhd file, the following references are near the top:
library ieee;
use ieee.std_logic_1164.ALL;
use ieee.numeric_std.ALL;
library UNISIM;
use UNISIM.Vcomponents.ALL;

> 
GHDL is a simulator, xilinx (XST) is a synthesizer.
Generaly you simulate your circuit with a simulator, then you check it
works, finally you run synthesis tool.


> Terminology is a bit confusing... analyze, elaborate, run?

these are VHDL terms.

analyze is like compilation stage (entities are compiled)
elaborate is like link stage (compiled entities are assembled in a
program and connected each others)

> 
> inside the vhd file, the following references are near the top:
> library ieee;
> use ieee.std_logic_1164.ALL;
> use ieee.numeric_std.ALL;
> library UNISIM;
> use UNISIM.Vcomponents.ALL;
> 
-P is the directory where ghdl search anlyzed libraries, so you have to
analyze unisim first! (with options: --workdir=dir_of_unsim_compilation
--work=unisim)

then you can use -Pdir_of_unsim_compilation to analyze you project