Home/Instructions/Shift Right Arithmetic Word
SRAW

RISC-V SRAW Instruction Details

Instruction ManualR-type

Shift lower 32 bits of rs1 right arithmetically by rs2[4:0], sign-extend 32-bit result to 64 bits

Instruction Syntax

sraw rd, rs1, rs2
Operand Breakdown
Destination rd: register receiving the operation result.
Source rs1: register holding the first operand.
Source rs2: register holding the second operand.
RV64IArithmetic32-bit Shift

Instruction Behavior

SRAW (R-type, opcode=0111011, funct7=0100000, funct3=101) performs an arithmetic right shift on the lower 32 bits of rs1 (original sign bit copied into vacated upper bits) by the shift amount in rs2[4:0]. The 32-bit result is sign-extended to 64 bits.

SRAW Decode And Execute Animation

Starts with machine-code field decoding, then shows operand reads, instruction-specific execution, and ISA-visible state update.

rd
rs1
rs2
sraw
,
,
Execution Context
a6(x16)
0xFFFFFFFFFFFFFFF0
sp(x2)
0x0000000000000002
31..25
24..20
19..15
14..12
11..7
6..0
0100000
funct7
00010
rs2
10000
rs1
101
funct3
00101
rd
0111011
opcode
Execution Data Path
instruction
0x402852BB
opcode
0111011 -> OP-32
funct3
101 -> SRAW
funct7
0100000 -> base ALU selector
rd / rs1 / rs2
t0(x5) / a6(x16) / sp(x2)
shamt
rs2[4:0]=00010 -> 2
32-bit arithmetic shift
0xFFFFFFF0 arithmetic >> 2 -> low 32 bits 0xFFFFFFFC -> sext.w 0xFFFFFFFFFFFFFFFC
x5
t0(x5) = 0xFFFFFFFFFFFFFFFC
Current Step

Concept Step: receive the 32-bit instruction encoding

The machine code is split by the current instruction format; the animation starts from encoding/decode.

encoding: 0x402852BB
syntax : sraw t0(x5), a6(x16), sp(x2)
result : t0(x5) = 0xFFFFFFFFFFFFFFFC
Architectural Result
t0(x5) = 0xFFFFFFFFFFFFFFFC

This animation shows ISA-visible decode and state changes, not any specific CPU pipeline, cache, prediction, or timing implementation.

Common Usage Scenarios

Bit Operations & Masks

Understand this scenario with real code like «sraw x10, x11, x12 # x10 = sign-extend((x11[31:0] >>> x12[4:0])[31:0])».

Pre-Use Checklist

Syntax Check
  • Verify rd, rs1, rs2 (and rs3) are valid GPRs.
  • Confirm funct3 and funct7 encoding is correct.
Semantic Check
  • Check if the result affects subsequent branches or address calculations.
  • Ensure the rd register is not overwritten by another instruction.

Pitfalls / Common Confusions

Arithmetic shift preserves sign, ensuring correct signed semantics after extension
W-suffix instructions produce a 32-bit result and sign-extend bit 31 to XLEN; do not treat them as ordinary 64-bit operations.
These W-suffix forms belong to RV64I; RV32 has no corresponding forms.
rd=x0 is a HINT designated for future standard use; it does not change architecturally visible state except PC and applicable performance counters, and an implementation may ignore it.