RISC-V ISA Explorer · Single-Letter Extensions

C: Compressed

Ratified 2019-12 · version 2.0.0

Short 16-bit encodings of common instructions, typically cutting program size by 25 to 30 percent.

Typical use: 16-bit instruction encodings

Specification

Open C in the explorer

Dependencies

Requires

Instructions (34)

Mnemonic	Name	Encoding	Match	Mask
`C.ADD`	Add	`----------------1001----------10`	`0x9002`	`0xf003`
`C.ADDI`	Add a sign-extended non-zero immediate	`----------------000-----------01`	`0x1`	`0xe003`
`C.ADDI16SP`	Add a sign-extended non-zero immediate	`----------------011-00010-----01`	`0x6101`	`0xef83`
`C.ADDI4SPN`	Add a zero-extended non-zero immediate, scaled by 4, to the stack pointer	`----------------000-----------00`	`0x0`	`0xe003`
`C.ADDIW`	Add a sign-extended non-zero immediate	`----------------001-----------01`	`0x2001`	`0xe003`
`C.ADDW`	Add word	`----------------100111---01---01`	`0x9c21`	`0xfc63`
`C.AND`	And	`----------------100011---11---01`	`0x8c61`	`0xfc63`
`C.ANDI`	And immediate	`----------------100-10--------01`	`0x8801`	`0xec03`
`C.BEQZ`	Branch if Equal Zero	`----------------110-----------01`	`0xc001`	`0xe003`
`C.BNEZ`	Branch if NOT Equal Zero	`----------------111-----------01`	`0xe001`	`0xe003`
`C.EBREAK`	Breakpoint exception	`----------------1001000000000010`	`0x9002`	`0xffff`
`C.J`	Jump	`----------------101-----------01`	`0xa001`	`0xe003`
`C.JAL`	Jump and Link	`----------------001-----------01`	`0x2001`	`0xe003`
`C.JALR`	Jump and Link Register	`----------------1001-----0000010`	`0x9002`	`0xf07f`
`C.JR`	Jump Register	`----------------1000-----0000010`	`0x8002`	`0xf07f`
`C.LD`	Load double	`----------------011-----------00`	`0x6000`	`0xe003`
`C.LDSP`	Load doubleword from stack pointer	`----------------011-----------10`	`0x6002`	`0xe003`
`C.LI`	Load the sign-extended 6-bit immediate	`----------------010-----------01`	`0x4001`	`0xe003`
`C.LUI`	Load Upper Immediate	`----------------011-----------01`	`0x6001`	`0xe003`
`C.LW`	Load word	`----------------010-----------00`	`0x4000`	`0xe003`
`C.LWSP`	Load word from stack pointer	`----------------010-----------10`	`0x4002`	`0xe003`
`C.MV`	Move Register	`----------------1000----------10`	`0x8002`	`0xf003`
`C.NOP`	Non-operation	`----------------000-00000-----01`	`0x1`	`0xef83`
`C.OR`	Or	`----------------100011---10---01`	`0x8c41`	`0xfc63`
`C.SD`	Store double	`----------------111-----------00`	`0xe000`	`0xe003`
`C.SDSP`	Store doubleword to stack	`----------------111-----------10`	`0xe002`	`0xe003`
`C.SLLI`	Shift left logical immediate	`----------------000-----------10`	`0x2`	`0xe003`
`C.SRAI`	Shift right arithmetical immediate	`----------------100-01--------01`	`0x8401`	`0xec03`
`C.SRLI`	Shift right logical immediate	`----------------100-00--------01`	`0x8001`	`0xec03`
`C.SUB`	Subtract	`----------------100011---00---01`	`0x8c01`	`0xfc63`
`C.SUBW`	Subtract word	`----------------100111---00---01`	`0x9c01`	`0xfc63`
`C.SW`	Store word	`----------------110-----------00`	`0xc000`	`0xe003`
`C.SWSP`	Store word to stack	`----------------110-----------10`	`0xc002`	`0xe003`
`C.XOR`	Exclusive Or	`----------------100011---01---01`	`0x8c21`	`0xfc63`