1,000+ ASIC Interview Questions: SystemVerilog, UVM & RTL

DescriptionQ291

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Q291ArchFollow-up to Q212ASIC interview problem

Reject invalid deallocation

TechniquesAllocatorValidationOwnership

DifficultyMedium

TopicMemory Systems

LanguageSystemVerilog

Requirements4 checkpoints

Problem

Detect zero-sized, double, partial, and otherwise invalid deallocation requests before they can corrupt the free list.

Function headerSystemVerilog

function bit alloc_checked(
  int unsigned size,
  output int unsigned addr
);

function bit dealloc_checked(
  int unsigned addr,
  int unsigned size
);

Example input and output

Use this case to check your interpretation

Input

recorded allocation: base=0x1000,size=0x20; dealloc_checked(0x1000,0x10)

Output

reject partial deallocation; allocation map and free list unchanged

Explanation

The base matches but the size does not, so exact allocation metadata prevents silent range corruption.

Requirements (4)

Route successful allocations through a wrapper that records size by returned base address.
Require an exact base and size match on deallocation.
Leave allocator state unchanged on failure.
Coalesce the returned interval after successful validation.