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15.1. Functions
A function is a procedural block that returns a single value. Functions execute in zero simulation time and cannot contain timing controls. They are primarily used for combinational logic operations and calculations.
Function Syntax and Structure
Verilog
Key Characteristics
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Must return EXACTLY ONE value
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At least ONE input (can have multiple)
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NO timing controls (#delay, @event, wait)
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Executes in ZERO simulation time
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Cannot call tasks (can call other functions)
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Return value assigned to function name
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Can have local variables
Basic Function Examples
Verilog
Function Return Types
Verilog
Calling Functions
Verilog
Advanced Function Examples
Verilog
Function Restrictions
⚠ RESTRICTIONS:
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Cannot contain timing controls (#, @, wait)
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Cannot call tasks
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Cannot have output or inout arguments
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Must have at least one input
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Must return exactly one value
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Cannot enable other tasks
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