SC.D

Store Conditional Doubleword

SC.D rd, rs2, (rs1)

Conditionally stores a 64-bit value to memory if the reservation is valid.

Encoding

Binary Layout

00011

31:27

aq

26

rl

25

rs2

24:20

rs1

19:15

011

14:12

rd

11:7

0101111

6:0

 

Format R-Type (Atomic)

Opcode 0x1800302F

Extension A

Operands

• rd
  Dest (0=Success)
• rs2
  Source Value
• rs1
  Address

Example

SC.D x10, x11, (x12)

// 64-bit conditional store.

Related

More in A

Reference

View in RISC-V Unprivileged ISA Specification ↗ RISC-V ISA Manual

Description

SC.D conditionally stores the doubleword in rs2 to the address in rs1, only if the reservation set by LR.D is still valid (RV64 only). It writes 0 to rd on success and a non-zero value on failure.

Operation

if (ReservationValid) { M[R[rs1]] = R[rs2]; R[rd] = 0; } else { R[rd] = 1; }