DescriptionQ262
Q262ArchFollow-up to Q212ASIC interview problem
Allocate on a power-of-two boundary
TechniquesAllocatorAlignmentBit mask
DifficultyMedium
TopicMemory Systems
LanguageSystemVerilog
Requirements4 checkpoints
01
Problem
Return a block whose starting address is aligned to a requested power-of-two boundary while preserving every unused fragment.
Function headerSystemVerilog
function bit alloc_aligned(
int unsigned size,
int unsigned align,
output int unsigned addr
);Example input and output
Use this case to check your interpretationInput
free=[[0x1003,0x10FF]]; size=0x20; alignment=0x40Output
base=0x1040; remaining=[[0x1003,0x103F],[0x1060,0x10FF]]Explanation
Rounding 0x1003 upward selects the first 64-byte boundary, and both unused fragments remain available.
02
Requirements (4)
- Reject zero or non-power-of-two alignment.
- Round each candidate range start upward without signed arithmetic.
- Verify that the complete request fits after alignment.
- Preserve leading and trailing free fragments.