- Fact:
- Sometimes, you need to use a
tailor-made component
multiple times
in your circuit
- This situation is like a tailor-made Java method that you call multiple times
- Sometimes, you need to use a
tailor-made component
multiple times
in your circuit
- Fact:
- You can create a C function that contains input/output signals and using logic-sim components in the body of the function to define new components
- Example:
- Suppose we want to
make the following component:
Inputs: a, b, c and d
Output: z
- C-function that implements
the component's functionality:
void NewComp( const Signal &a, const Signal &b, const Signal &c, const Signal &d, const Signal &z) { Sig(x,1); Sig(y,1); And( "bb", (a,b), x ); And( "bb", (c,d), y ); Or ( "bb", (x,y), z); }Note:
- We must pass all signal parameters by reference because the logic-sim simulate must update the signal variables !!!
- Suppose we want to
make the following component:
- Note:
- We did not include
a coordinate parameter in the
new component
- The coordinate parameter is not necessary
- However, it is generally
preferred to have
a coordinate parameter so the
componenet can be
place at a
specify location in the
simulation area
We will learn how to do this later
- We did not include
a coordinate parameter in the
new component
- Important:
- The data type of
a signal parameter is
always:
const Signal &
- The data type of
a signal parameter is
always:
- The & symbol
means:
- The parameter is passed by reference (this is C++'s notation)
- Fact:
- The signal parameter is
always an
array !!!
- Recall that:
- A single signal in
logic-sim is
actually an
array of 1 signal !!!
See: click here
- A single signal in
logic-sim is
actually an
array of 1 signal !!!
- The signal parameter is
always an
array !!!
- We can create
as many copies of
the new component as we
want by using the
function name as
component name !!!
Syntax to create a component:
ComponentFunctionName( parameters ) ;Note:
- Make sure the parameters given to the ComponentFunctionName( ) matches the definition !!!
- Example:
void NewComp( const Signal &a, const Signal &b, const Signal &c, const Signal &d, const Signal &z ) { Sig(x,1); Sig(y,1); And( "bb", (a,b), x ); And( "bb", (c,d), y ); Or ( "bb", (x,y), z); } /* ----- Set up circuit that uses "NewComp" ----- */ void simnet() { Sig(in0,1); Sig(in1,1); Sig(in2,1); Sig(in3,1); Sig(out,1); /* The input bits to the mux */ Switch ( "aa", in0, '0', Zero ); Switch ( "ba", in1, '1', Zero ); Switch ( "ca", in2, '2', Zero ); Switch ( "da", in3, '3', Zero ); NewComp( in0, in1, in2, in3, out ); // Use the NewComp component Probe ( "ce", out ); }
- Example Program:
(Demo above code)
- Prog file: click here
How to run the program:
- Right click on link and
save in a scratch directory
- To compile: cs355sim macro1
- To run: ./simex
Result:
- Suppose we want a new component
to look like this:
(A box instead of exposed internal circuits)
- You can achieve this effect
by making 3 changes:
- Pass a
parameter of the type
const SD & to the
new component function
- Call this method
using the
const SD & parameter:
Module ( SD-param, "NameOfComp", input-signals, output-signals );
- Change every coordinate
of components used in the function
from
"xy" to:
SD ( SD-param , "xy" );
- Pass a
parameter of the type
const SD & to the
new component function
- Example:
- Original component function:
void NewComp( const Signal &a, const Signal &b, const Signal &c, const Signal &d, const Signal &z) { Sig(x,1); Sig(y,1); And( "bb", (a,b), x ); And( "bb", (c,d), y ); Or ( "bb", (x,y), z); }
- Function with the
above changes:
void NewComp ( const SD &coord, const Signal &a, const Signal &b, const Signal &c, const Signal &d, const Signal &z) { Module( coord, "NewCompName", (a,b,c,d), z); // Make module with (a,b,c,d) as input // and z as output Sig(x,1); Sig(y,1); And( SD(coord,"bb") , (a,b), x ); And( SD(coord,"bb") , (c,d), y ); Or ( SD(coord,"bb") , (x,y), z); }
- Original component function:
- Example Program:
(Demo above code)
- Prog file: click here
How to run the program:
- Right click on link and
save in a scratch directory
- To compile: cs355sim macro2
- To run: ./simex
Result:
Note:
- You can use the control-M and control-N keys to expose/hide the internal details of user-defined components
- Fact:
- A user component will
be displayed as
a rectagular box
- You will not see
the circuit components
used inside the
user component
(Unless you toggle the control-N key that exposed the inside)
- A user component will
be displayed as
a rectagular box
- Since you do not
see the "mess" inside,
my advice is:
- Always use the
same coordinate,
e.g.:
And( SD(coord,"bb") , (a,b), x ); And( SD(coord,"bb") , (c,d), y ); Or ( SD(coord,"bb") , (x,y), z);
- Always use the
same coordinate,
e.g.:
- In class, we have seen that a
4×1 multiplexor
can be constructed as follows:
- The stand-alone circuit
shown in class:
Not ( "db", c0, not_c0 ); Not ( "db", c1, not_c1 ); And ( "ac", (i0, not_c1, not_c0), out_0 ); And ( "ac", (i1, not_c1, c0), out_1 ); And ( "bc", (i2, c1, not_c0), out_2 ); And ( "bc", (i3, c1, c0), out_3 ); Or ( "ad", (out_0, out_1, out_2, out_3), out );
- Example Program:
(Demo above code)
- Prog file: click here (or: click here )
How to run the program:
- Right click on link and
save in a scratch directory
- To compile: cs355sim mux
- To run: ./simex
- We can make our own
Multiplexor component as follows:
void MyMux( const SD &coord, const Signal &i3, const Signal &i2, const Signal &i1, const Signal &i0, const Signal &c1, const Signal &c0, const Signal &out ) { Signal out_0, out_1, out_2, out_3, not_c0, not_c1; Module( coord, "MyMux", (i3,i2,i1,i0,c1,c0), out); Not ( SD(coord,"db"), c0, not_c0 ); Not ( SD(coord,"db"), c1, not_c1 ); And ( SD(coord,"ac"), (i0, not_c1, not_c0), out_0 ); And ( SD(coord,"ac"), (i1, not_c1, c0), out_1 ); And ( SD(coord,"bc"), (i2, c1, not_c0), out_2 ); And ( SD(coord,"bc"), (i3, c1, c0), out_3 ); Or ( SD(coord,"ad"), (out_0, out_1, out_2, out_3), out ); }Notice that the control signals (c0, c1) are input signals !!!
- The Multiplexor component can
then be used as follows:
MyMux ( "cc", i3, i2, i1, i0, c1, c0, out );
- Example Program:
(Demo above code)
- Prog file: click here
How to run the program:
- Right click on link and
save in a scratch directory
- To compile: cs355sim mux-comp
- To run: ./simex
- Notice the different input
signal to the multiplexor:
MyMux ( "cc", i3, i2, i1, i0, c1, c0, out );
Observe:
i3, i2, i1, i0 are input signals c1, c0 are control signals - Fact:
- It would be easier to
pass an
array of
signals:
array of input signals array of control signals
- It would be easier to
pass an
array of
signals:
- The MyMux component
re-written with
2 array parameters:
void MyMux( const SD &coord, const Signal &i, const Signal &c, // i and c are arrays const Signal &out ) { Signal out_0, out_1, out_2, out_3, not_c0, not_c1; Module( coord, "MyMux", (i,c), out); Not ( SD(coord,"db"), c[0], not_c0 ); Not ( SD(coord,"db"), c[1], not_c1 ); And ( SD(coord,"ac"), (i[0], not_c1, not_c0), out_0 ); And ( SD(coord,"ac"), (i[1], not_c1, c[0]), out_1 ); And ( SD(coord,"bc"), (i[2], c[1], not_c0), out_2 ); And ( SD(coord,"bc"), (i[3], c[1], c[0]), out_3 ); Or ( SD(coord,"ad"), (out_0, out_1, out_2, out_3), out ); }
- To use the
new implementation,
you must
pass an
array as
parameter:
MyMux ( "ab-dd", (in3, in2, in1, in0), (co1, co0), out ); // ^^^^^^^^^^^^^^^^^^^ ^^^^^^^^ // Pass 2 arrays of signals
- Example Program:
(Demo above code)
- Prog file: click here
How to run the program:
- Right click on link and
save in a scratch directory
- To compile: cs355sim mux-comp2
- To run: ./simex