What is a case statement in Verilog?

In Verilog, a case statement includes all of the code between the Verilog keywords, case (“casez”, “casex”), and endcase. A case statement can be a select-one-of-many construct that is roughly like Associate in nursing if-else-if statement.

How do you write a case statement in Verilog?

ncsim> run [0] a=0x4 b=0x1 c=0x1 sel=0b11 out=0x0 [10] a=0x5 b=0x5 c=0x5 sel=0b10 out=0x5 [20] a=0x1 b=0x5 c=0x6 sel=0b01 out=0x5 [30] a=0x5 b=0x4 c=0x1 sel=0b10 out=0x1 [40] a=0x5 b=0x2 c=0x5 sel=0b11 out=0x0 ncsim: *W,RNQUIE: Simulation is complete.

What is difference between Case and casez used in Verilog?

casex ignores any bit position containing an X or Z; casez only ignores bit positions with a Z. Verilog literals use the both the? and z characters to represent the Z state.

What is Verilog Case 1 )?

In Verilog, a case expression can either be a constant, such as “1’b1” (one bit of ‘1’, or “true”), it can be an expression that evaluates to a constant value, or most often it is a bit or vector of bits that are used to compare against case items.

What is full case and parallel case in Verilog?

A case statement in Verilog is said to be a parallel case when it isn’t possible for multiple case items to be equal in value to the case-expression. The significance of parallel case statements is that case statements that are not parallel infer priority logic during synthesis.

Are cases synthesizable?

Both casex and casez are synthesizable. Casex generates a don’t-care space for unspecified state points. Casez uses a “Z logic value” to represent a don’t-care bits.

Is case statement synthesizable in Verilog?

The Verilog Case Statement works exactly the way that a switch statement in C works. A note about synthesis: When case statements are synthesized by the tools, they generate optimized decode logic to quickly select which case statement is valid.

What is always * in Verilog?

1.1 always@ Blocks. always@ blocks are used to describe events that should happen under certain conditions. always@ blocks. are always followed by a set of parentheses, a begin, some code, and an end.

What is the difference between full case and parallel case?

When all possible binary values of the expression are covered by the item expressions, the statement is known as a full case statement. A gets a don’t care value when no match occur. From synthesis point of view, a parallel case statement infers a multiplexing routing network.

What is synthesizable in Verilog?

Synthesizable Verilog is that subset of the language that are accepted by the synthesis tools. The non-synthesizable constructs are used only for simulation and the synthesis tool cannot handle them.

Is for loop synthesizable in Verilog?

for loop is a synthesizable construct in verilog. However for loops should only be used in combinational always blocks.