Q291FreeSystemVerilog

Reject invalid deallocation

Difficulty: Medium
Topic: Memory Systems
Language: SV

Interview prompt

Question

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

Starting point

Question code

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

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

Reviewed example

Trace one case

Input

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

Expected output

reject partial deallocation; allocation map and free list unchanged

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

What to cover

Requirements

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.

Continue practicing

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Question

Question code

Trace one case

Requirements

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