RISC-V ISA Explorer · Bit Manipulation (Zb*)

Zbb: Basic Bitmanip

Ratified 2021-06 · version 1.0.0

Common bit and word operations such as count leading zeros, population count, min/max, rotate and sign extend.

Typical use: Bit counting, min/max and byte swapping

Specification

Open Zbb in the explorer

Dependencies

Required by

Instructions (25)

Mnemonic	Name	Encoding	Match	Mask
`ANDN`	AND with inverted operand	`0100000----------111-----0110011`	`0x40007033`	`0xfe00707f`
`CLZ`	Count leading zero bits	`011000000000-----001-----0010011`	`0x60001013`	`0xfff0707f`
`CLZW`	Count leading zero bits in word	`011000000000-----001-----0011011`	`0x6000101b`	`0xfff0707f`
`CPOP`	Count set bits	`011000000010-----001-----0010011`	`0x60201013`	`0xfff0707f`
`CPOPW`	Count set bits in word	`011000000010-----001-----0011011`	`0x6020101b`	`0xfff0707f`
`CTZ`	Count trailing zero bits	`011000000001-----001-----0010011`	`0x60101013`	`0xfff0707f`
`CTZW`	Count trailing zero bits in word	`011000000001-----001-----0011011`	`0x6010101b`	`0xfff0707f`
`MAX`	Maximum	`0000101----------110-----0110011`	`0xa006033`	`0xfe00707f`
`MAXU`	Unsigned maximum	`0000101----------111-----0110011`	`0xa007033`	`0xfe00707f`
`MIN`	Minimum	`0000101----------100-----0110011`	`0xa004033`	`0xfe00707f`
`MINU`	Unsigned minimum	`0000101----------101-----0110011`	`0xa005033`	`0xfe00707f`
`ORC.B`	Bitware OR-combine, byte granule	`001010000111-----101-----0010011`	`0x28705013`	`0xfff0707f`
`ORN`	OR with inverted operand	`0100000----------110-----0110011`	`0x40006033`	`0xfe00707f`
`REV8`	Byte-reverse register (RV64 encoding)	`011010111000-----101-----0010011`	`0x6b805013`	`0xfff0707f`
`ROL`	Rotate left (Register)	`0110000----------001-----0110011`	`0x60001033`	`0xfe00707f`
`ROLW`	Rotate left word (Register)	`0110000----------001-----0111011`	`0x6000103b`	`0xfe00707f`
`ROR`	Rotate right (Register)	`0110000----------101-----0110011`	`0x60005033`	`0xfe00707f`
`RORI`	Rotate right (Immediate)	`011000-----------101-----0010011`	`0x60005013`	`0xfc00707f`
`RORIW`	Rotate right word (Immediate)	`0110000----------101-----0011011`	`0x6000501b`	`0xfe00707f`
`RORW`	Rotate right word (Register)	`0110000----------101-----0111011`	`0x6000503b`	`0xfe00707f`
`SEXT.B`	Sign-extend byte	`011000000100-----001-----0010011`	`0x60401013`	`0xfff0707f`
`SEXT.H`	Sign-extend halfword	`011000000101-----001-----0010011`	`0x60501013`	`0xfff0707f`
`XNOR`	Exclusive NOR	`0100000----------100-----0110011`	`0x40004033`	`0xfe00707f`
`ZEXT.H`	Zero-extend halfword	`000010000000-----100-----0111011`	`0x800403b`	`0xfff0707f`
`ZEXT.H.RV32`		`000010000000-----100-----0110011`	`0x8004033`	`0xfff0707f`