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Can the wire data type be used on the left side of the assignment statement in a procedural block?
A “wire” type variable. Correct answer is (d). In a procedural assignment statement, only register type variables or part select thereof can be used in the left hand side. A wire type variable cannot be assigned a value within a procedural block.
What is continuous assignment statement in verilog?
Continuous assign statements are used to drive values on to wires. For example: assign a = b & c; This is referred to as a continuous assign because the wire on the left-hand side of the assignment operator is continuously driven with the value of the expression on the right hand side.
What is deassign in verilog?
The assign and deassign procedural assignment statements allow continuous assignments to be placed onto registers for controlled periods of time. The assign procedural statement overrides procedural assignments to a register. The deassign procedural statement ends a continuous assignment to a register.
Can assign be used inside always block?
Assign is a continuous assignment statement which is used with wires in Verilog. assign statements don’t go inside procedural blocks such as always. Registers can be given values in an always block.
What is the difference between blocking and non-blocking assignments?
The output of an assign statement is always equal to the specified function of it’s inputs. “blocking” and “nonblocking” assignments only exist within always blocks. A blocking assignment takes affect immediately it is processed. A nonblocking assignment takes place at the end of processing the current “time delta”.
What is difference between register and wire?
Wire is used as combinational logic. Reg can be used as either combinational or sequential logic. In always@ block, you have to use reg to assign for a value, e.g. ‘=’ or ‘<=’. You cannot use assign with reg.
Is it illegal to use ModelSim in Verilog?
I’m a verilog noob and I have to do this ALU for a processor but I get this error for this line: I’m using modelsim. assign statements are only legal on wire types, not reg types. Alternatively, remove the reg declaration from SP_out to treat it as a wire, then your assign statement will work. Both options will behave in the exact same way.
When to use continuous assignment outside the always block?
It is there for very special modeling cases. continuous assignment, or assign outside the always block is there for connecting nets and used all over the places. lhs of such an assignment must be a net type, i.e. wire. it cannot be a reg. On the other hand all lhs in always blocks must be of ‘reg’ type.
Can a result be assigned to an always block?
You have declared result in you module declaration to be of type wire. You can’t assign values to wires in always blocks. Instead you should declare result as the correct type as explained in this StackOverflow question (thanks @Greg). This makes it of reg type which can be assigned in an always block. However, this is not your only problem.
Can you assign values to wires in always blocks?
You can’t assign values to wires in always blocks. Instead you should declare result as the correct type as explained in this StackOverflow question (thanks @Greg). This makes it of reg type which can be assigned in an always block. However, this is not your only problem. You are assigning values to temp_reg in two different always blocks.