myhdl-list

[myhdl-list] enums and non-local

[JOSE M. G. C. <jm....@ub...>]

Hello all,

I am trying to use an enumeration to define the states of a finite state machine. There are examples where it seems to work, but I am not able to do that. Moreover, I have gone through the code and in the _analyze.py module it seems that only intbv are allowed to be seen as non-locals. I assume there is a reason for this filtering, but there is no information. Can anyone provide a hint?

        Thanks in advance,

                Jose M.



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Re: [myhdl-list] enums and non-local

[Christopher F. <chr...@gm...>]

On 2/11/2015 1:11 AM, JOSE MARIA GOMEZ CAMA wrote:
> Hello all,
>
> I am trying to use an enumeration to define the states of a finite state machine. There are examples where it seems to work, but I am not able to do that. Moreover, I have gone through the code and in the _analyze.py module it seems that only intbv are allowed to be seen as non-locals. I assume there is a reason for this filtering, but there is no information. Can anyone provide a hint?

Do you have an example of the enumeration not working?  I
have used it many times, you can peruse this example if
you like:
https://github.com/schoeberl/comphdl/blob/master/myhdl/vending/vending.py#L31

Also the examples on the MyHDL website:
http://www.myhdl.org/examples/sinecomp/#design

The nonlocals are a little more complicated and will be
enhanced (!) when porting to Py3k is completed.  In general
using /intbv/ is the safest approach.


     def m_some_module(*portmap):

         myvar = intbv(0, min=-8, max=8)

         @always...
         def rtl():
            myvar[:] = x + 1
            ...


Hope that helps,
Chris

Re: [myhdl-list] enums and non-local

[Jose M. G. C. <ch...@gm...>]

This is a piece of code that does not work. I think it is more or less equivalent to yours.


from myhdl import *

def test(clk, reset, a, b):
    t_state = enum("WAIT", "CALC")
    state = Signal(t_state.WAIT)
    @always_seq(clk.posedge, reset)
    def fsm():
        if state == t_state.WAIT:
            b.next = 0
            state.next = t_state.CALC
        elif state == t_state.CALC:
            a.next = b
            state = t_state.WAIT
    return fsm

clk = Signal(intbv(0)[1:])
reset = ResetSignal(1, active=1, async=False)
a = Signal(intbv(0)[1:])
b = Signal(intbv(0)[1:])

toVHDL(test, clk, reset, a, b)

The error is:

Local variable may be referenced before assignment: state

Thanks for your help,

	Jose M.


> El 11/2/2015, a las 14:45, Christopher Felton <chr...@gm...> escribió:
> 
> On 2/11/2015 1:11 AM, JOSE MARIA GOMEZ CAMA wrote:
>> Hello all,
>> 
>> I am trying to use an enumeration to define the states of a finite state machine. There are examples where it seems to work, but I am not able to do that. Moreover, I have gone through the code and in the _analyze.py module it seems that only intbv are allowed to be seen as non-locals. I assume there is a reason for this filtering, but there is no information. Can anyone provide a hint?
> 
> Do you have an example of the enumeration not working?  I
> have used it many times, you can peruse this example if
> you like:
> https://github.com/schoeberl/comphdl/blob/master/myhdl/vending/vending.py#L31
> 
> Also the examples on the MyHDL website:
> http://www.myhdl.org/examples/sinecomp/#design
> 
> The nonlocals are a little more complicated and will be
> enhanced (!) when porting to Py3k is completed.  In general
> using /intbv/ is the safest approach.
> 
> 
>     def m_some_module(*portmap):
> 
>         myvar = intbv(0, min=-8, max=8)
> 
>         @always...
>         def rtl():
>            myvar[:] = x + 1
>            ...
> 
> 
> Hope that helps,
> Chris
> 
> 
> 
> ------------------------------------------------------------------------------
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Re: [myhdl-list] enums and non-local

[Henry G. <he...@ca...>]

On 11/02/15 15:47, Jose M. Gomez Cama wrote:
> This is a piece of code that does not work. I think it is more or less equivalent to yours.
>
>
> from myhdl import *
>
> def test(clk, reset, a, b):
>      t_state = enum("WAIT", "CALC")
>      state = Signal(t_state.WAIT)
>      @always_seq(clk.posedge, reset)
>      def fsm():
>          if state == t_state.WAIT:
>              b.next = 0
>              state.next = t_state.CALC
>          elif state == t_state.CALC:
>              a.next = b
>              state = t_state.WAIT
>      return fsm
>
> clk = Signal(intbv(0)[1:])
> reset = ResetSignal(1, active=1, async=False)
> a = Signal(intbv(0)[1:])
> b = Signal(intbv(0)[1:])
>
> toVHDL(test, clk, reset, a, b)
>
> The error is:
>
> Local variable may be referenced before assignment: state

You're trying to assign state here:

         elif state == t_state.CALC:
             a.next = b
             state = t_state.WAIT

Perhaps you want `state.next = t_state.WAIT`?

Henry

Re: [myhdl-list] enums and non-local

[Jose M. G. C. <ch...@gm...>]

Ups, you are right...

	Sorry

> El 11/2/2015, a las 17:35, Christopher Felton <chr...@gm...> escribió:
> 
> <snip>
>> 
>> You're trying to assign state here:
>> 
>>          elif state == t_state.CALC:
>>              a.next = b
>>              state = t_state.WAIT
>> 
>> Perhaps you want `state.next = t_state.WAIT`?
>> 
> 
> Yup, what Henry said.
> 
> Regards,
> Chris
> 
> 
> 
> ------------------------------------------------------------------------------
> Dive into the World of Parallel Programming. The Go Parallel Website,
> sponsored by Intel and developed in partnership with Slashdot Media, is your
> hub for all things parallel software development, from weekly thought
> leadership blogs to news, videos, case studies, tutorials and more. Take a
> look and join the conversation now. http://goparallel.sourceforge.net/
> _______________________________________________
> myhdl-list mailing list
> myh...@li...
> https://lists.sourceforge.net/lists/listinfo/myhdl-list

Re: [myhdl-list] enums and non-local

[Christopher F. <chr...@gm...>]

On 2/11/2015 1:57 PM, Jose M. Gomez Cama wrote:
> Ups, you are right...
>
> 	Sorry
>

No problem!  Glad we could help.

Chris

Re: [myhdl-list] enums and non-local

[Christopher F. <chr...@gm...>]

<snip>
>
> You're trying to assign state here:
>
>           elif state == t_state.CALC:
>               a.next = b
>               state = t_state.WAIT
>
> Perhaps you want `state.next = t_state.WAIT`?
>

Yup, what Henry said.

Regards,
Chris