Sid: Is there a bus selector component?

Sid: Is there a bus selector component?

[Dave Brolley]

Hi,

I have a need for the inverse of the hw-glue-bus-mux component. I need
something that takes multiple buses as inputs and uses a pin as an
input selector to map one bus at a time to an output accessor. The
other buses would return sid::bus::not_mapped if any attempt was made
to access them. My current need is to map 2 buses onto one accessor.

Do we have anything like this? I'm not very familiar with the
component library.

Thanks,
Dave

Re: Sid: Is there a bus selector component?

[Ben Elliston]

>>>>> "Dave" == Dave Brolley <brolley@redhat.com> writes:

  Dave> Do we have anything like this? I'm not very familiar with the
  Dave> component library.

I believe there isn't such a component, but the place to look is the
component/CATALOG file.

Ben

Re: Sid: Is there a bus selector component?

[Ben Elliston]

>>>>> "Dave" == Dave Brolley <brolley@redhat.com> writes:

  Dave> I have a need for the inverse of the hw-glue-bus-mux
  Dave> component. I need something that takes multiple buses as
  Dave> inputs and uses a pin as an input selector to map one bus at a
  Dave> time to an output accessor.

What you're describing *is* a multiplexer.  So what is the existing
hw-glue-bus-mux, then?  A decoder?

Ben

Re: Sid: Is there a bus selector component?

[Dave Brolley]

Ben Elliston wrote:

>>>>>> "Dave" == Dave Brolley <brolley@redhat.com> writes:
>>>>> 
> 
>   Dave> I have a need for the inverse of the hw-glue-bus-mux
>   Dave> component. I need something that takes multiple buses as
>   Dave> inputs and uses a pin as an input selector to map one bus at a
>   Dave> time to an output accessor.
> 
> What you're describing *is* a multiplexer.  So what is the existing
> hw-glue-bus-mux, then?  A decoder?
> 
> Ben
> 
> 
It maps one input bus to multiple output accessors.

Dave

Re: Sid: Is there a bus selector component?

[Ben Elliston]

>>>>> "Dave" == Dave Brolley <brolley@redhat.com> writes:

  Dave> I have a need for the inverse of the hw-glue-bus-mux
  Dave> component. I need something that takes multiple buses as
  Dave> inputs and uses a pin as an input selector to map one bus at a
  Dave> time to an output accessor.
  >> 
  >> What you're describing *is* a multiplexer.  So what is the existing
  >> hw-glue-bus-mux, then?  A decoder?

  Dave> It maps one input bus to multiple output accessors.

That doesn't sound like a mux to me -- that's a demux.

Ben

Re: Sid: Is there a bus selector component?

[Frank Ch. Eigler]

Hi -

On Wed, Mar 28, 2001 at 06:43:27PM -0500, Dave Brolley wrote:
: I have a need for the inverse of the hw-glue-bus-mux component. [...]

Interesting - why?

: Do we have anything like this? I'm not very familiar with the
: component library.

Nope.  It should not be hard to write one.

- FChE
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Re: Sid: Is there a bus selector component?

[Dave Brolley]

After some thought, it looks like I could do this with two of the 
existing bus-bux components:

connect-pin control selector -> mux1 switch
connect-pin control selector -> mux2 switch

connect-bus master1 bus mux1 upstream
connect-bus master2 bus mux2 upstream

connect-bus mux1 downstream1 slave read-write-port
# don't connect mux1 downstream2 to anything
# don't connect mux2 downstream1 to anything
connect-bus mux2 downstream2 slave read-write-port

Turns out that bux-mux returns sid::bus::unmapped if the selected 
accessor is not connected.

Any objections if I punt on the new selector component and just do this?

Dave

Frank Ch. Eigler wrote:

> Hi -
> 
> On Wed, Mar 28, 2001 at 06:43:27PM -0500, Dave Brolley wrote:
> : I have a need for the inverse of the hw-glue-bus-mux component. [...]
> 
> Interesting - why?
> 
> : Do we have anything like this? I'm not very familiar with the
> : component library.
> 
> Nope.  It should not be hard to write one.
> 
> - FChE

Re: Sid: Is there a bus selector component?

[Frank Ch. Eigler]

Hi -

brolley wrote:
: After some thought, it looks like I could do this with two of the 
: existing bus-bux components: [...]

Very good -- sort of like two pass-transistors.

: Any objections if I punt on the new selector component and just do this?

No problem -- IMO this is even better.

- FChE
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