AMOCAS.D

Atomic Compare and Swap Doubleword

AMOCAS.D rd, rs2, (rs1)

Atomically compares 64-bit memory at rs1 with rd; if equal, writes rs2 to memory.

AMOCAS.D atomically compares a doubleword in memory with a register pair and conditionally swaps it with another register pair (RV64 only).

atomic { if(M[rs1]==R[rd]) M[rs1]=R[rs2]; R[rd]=M[rs1]; }

AMOCAS.D t0, a1, a0

Binary Layout

00101

31:27

rs2

24:20

rs1

19:15

011

14:12

11:7

0101111

6:0

Format R-Type (Atomic)

Opcode 0x2F

Extension Zacas