v0.18.0: Zbs + Zbc Bit-Manipulation Extensions

Zbs — Single-Bit Manipulation

• BCLR/BCLRI: Clear a single bit by index
• BSET/BSETI: Set a single bit by index
• BINV/BINVI: Invert a single bit by index
• BEXT/BEXTI: Extract a single bit (returns 0 or 1)

Zbc — Carry-less Multiplication

• CLMUL: Carry-less multiply (lower 64 bits)
• CLMULH: Carry-less multiply high (upper 64 bits)
• CLMULR: Carry-less multiply reversed

Used by Linux for CRC calculations, cryptography, and GF(2) arithmetic.

Stats

• 130 tests passing (123 → 130)
• DTB updated with zbs, zbc extensions
• Full: RV64IMACSU + Zba + Zbb + Zbs + Zbc