use of FIFO

[user456]

Hi there ,

 

I am about implementing a directories based cache coherence protocol in systemc

 

But when i try to use the FIFO channel i couldn't  know how it works(methods,linking...)

can anyone suggest a tutorial or something like

 

I appriciate your feedback;

 

thx in advance 

[Rahul]

Though i am not an expert in a systemC. i can provide some information about sc_fifo and its methods and usage.

 

 

CHANNELS IN SYSTEM C

 

•A channel implements one or more interfaces, and serves as a container for communication functionality

•Different channels may implement the same interface in different ways

•A channel may implement more than one interface

•A channel may be connected to more than two modules

•A distinction is made between primitive channelsand hierarchical channels

 

Primitive channels:

 

sc_fifo is type of Primitive channels used largely in systemC

 

•A channel is primitive when it does not contain any hierarchy or process

•All primitive channels are derived from the base class called sc_prim_channel

•SystemC contains several built-in channels. The simplest are: sc_signal, sc_mutex, sc_semaphore and sc_fifo

 

sc_fifo

By default, an sc_fifo<> has a depth of 16. The data type (i.e.,typename) of the elements also needs to be specified. An sc_fifo may contain any data type including large and complex structures

 

Implements interface: sc_fifo_in_if, sc_fifo_out_if

 

Methods:

 

nb_read() Non-blocking read, returns bool, false if fifo is empty, true if read successful

 

read()  Returns current value of signal . Blocking for sc_fifo

 

read(port/signal) Returns void, current value of signal is stored in port_or_signal. Blocking for sc_fifo

 

operator=()  Assignment operator For convenience, does a write()

 

write(val) Schedules val to be written to the signal at the next update phase. Blocking for sc_fifo

 

nb_write(val) Non-blocking write, returns bool, false if fifo is full, true if write successful

 

num_free()  Returns int, number of remaining elements that can be written before fifo is full

 

num_available() Returns int, number of elements that are in the fifo

 

kind() Returns channel type (sc_buffer or sc_fifo etc)

 

 

Custom ports: sc_fifo_in<T>, sc_fifo_out<T>

 

 

Specify fifo depth in sc_main:  sc_fifo<T> f(10);  //Depth is 10

 

Specify fifo depth in a module: SC_CTOR(module_name): f(10)

 

 

 

Regards

Rahul

[user456]

thx Rahul , I appreciate that 

 

 

But one more question how should I link the ports :

 

I mean if I have N ports and want to link them to this FIFO

suppose we have:

 

SC_MODULE(module)

{

sc_out<bool> exit;

 

SC_CTOR(module)

{

...

}

~module;

}

 

in my main:

sc_fifo<int> my_fifo(N);

 

module M1;//suppose have N object type module

 

how to link the ports of the N modules to my_fifo ?

 

thx in advance

[bennygato]

thx Rahul , I appreciate that 

 

 

But one more question how should I link the ports :

 

I mean if I have N ports and want to link them to this FIFO

suppose we have:

 

SC_MODULE(module)

{

sc_out<bool> exit;

 

SC_CTOR(module)

{

...

}

~module;

}

 

in my main:

sc_fifo<int> my_fifo(N);

 

module M1;//suppose have N object type module

 

how to link the ports of the N modules to my_fifo ?

 

thx in advance

 

I also have the same question. have you figure out how to do it? thanks.

[user456]

hi bennygato;

 

In fact i advise you to download "IEEE Standard for Standard SystemC® Language Reference Manual" it help you understanding .

 

 

hope it help

 

[dakupoto]

thx Rahul , I appreciate that 

 

 

But one more question how should I link the ports :

 

I mean if I have N ports and want to link them to this FIFO

suppose we have:

 

SC_MODULE(module)

{

sc_out<bool> exit;

 

SC_CTOR(module)

{

...

}

~module;

}

 

in my main:

sc_fifo<int> my_fifo(N);

 

module M1;//suppose have N object type module

 

how to link the ports of the N modules to my_fifo ?

 

thx in advance

Hello Sir,

Are you trying to have a N x M FIFO ? That is,

N input ports driving data into a FIFO, with M

output ports, and N > 1, M > 1.

I am afraid the latest SystemC does not support

this FIFO structure, and you would have to

create one of your own -- create your own

FIFO, with appropriate schemes that will

prevent data overwrites in the FIFO.

Currently, only 1 x N FIFOs are available.

As you might understand, a N x M FIFO is

a complete project by itself.

Hope that helps.