15.3. Static and Automatic Behavior
The storage allocation for task and function variables can be either static (default) or automatic. This determines the lifetime and sharing of local variables.
15.3.1. Static Tasks/Functions (Default)
In static tasks/functions, local variables are allocated once and shared across all invocations. They retain their values between calls.
Characteristics
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Variables allocated ONCE at elaboration
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All calls share the SAME storage
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Values retained between calls
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NOT re-entrant safe
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Default behavior
Example
Verilog
15.3.2. Automatic Tasks/Functions
In automatic tasks/functions, local variables are allocated dynamically for each call. Each invocation gets its own storage space.
Characteristics
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Variables allocated on EACH call
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Each call has SEPARATE storage
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Values NOT retained between calls
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RE-ENTRANT safe
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Required for recursion
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Must use 'automatic' keyword
Syntax
Verilog
Example - Recursive Factorial
Verilog
15.3.3. Comparison: Static vs Automatic
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