Load Exclusive Register Halfword derives an address from a base register value, loads a halfword from memory, zero-extends it and writes it to a register. The memory access is atomic. The PE marks the physical address being accessed as an exclusive access. This exclusive access mark is checked by Store Exclusive instructions. See Synchronization and semaphores. For information about memory accesses see Load/Store addressing modes.
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | (1) | (1) | (1) | (1) | (1) | 0 | (1) | (1) | (1) | (1) | (1) | Rn | Rt | ||||||||
size | L | Rs | o0 | Rt2 |
integer n = UInt(Rn); integer t = UInt(Rt);
<Wt> |
Is the 32-bit name of the general-purpose register to be transferred, encoded in the "Rt" field. |
<Xn|SP> |
Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field. |
bits(64) address; bits(16) data; if n == 31 then CheckSPAlignment(); address = SP[]; else address = X[n]; // Tell the Exclusive Monitors to record a sequence of one or more atomic // memory reads from virtual address range [address, address+dbytes-1]. // The Exclusive Monitor will only be set if all the reads are from the // same dbytes-aligned physical address, to allow for the possibility of // an atomicity break if the translation is changed between reads. AArch64.SetExclusiveMonitors(address, 2); data = Mem[address, 2, AccType_ATOMIC]; X[t] = ZeroExtend(data, 32);
Internal version only: isa v25.07, AdvSIMD v23.0, pseudocode v31.3
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