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Shared Pseudocode
Proprietary Notice

CPYP, CPYM, CPYE

Memory copy

These instructions copy a requested number of bytes in memory from a source address to a destination address. The prologue, main, and epilogue instructions are expected to be run in succession and to appear consecutively in memory: CPYP, then CPYM, and then CPYE.

CPYP performs some preconditioning of the arguments suitable for using the CPYM instruction, and copies an IMPLEMENTATION DEFINED portion of the requested number of bytes. CPYM copies a further IMPLEMENTATION DEFINED portion of the remaining bytes. CPYE copies any final remaining bytes.

Note

The ability to copy an IMPLEMENTATION DEFINED number of bytes allows an implementation to optimize how the bytes being copied are divided between the different instructions.

For more information on exceptions specific to memory copy instructions, see Memory Copy and Memory Set exceptions.

The architecture supports two algorithms for the memory copy: option A and option B. Which algorithm is used is IMPLEMENTATION DEFINED.

Note

Portable software should not assume that the choice of algorithm is constant.

For CPYP:

On completion of CPYP, option A:

On completion of CPYP, option B:

For CPYM, option A, when PSTATE.C = 0:

For CPYM, option B, when PSTATE.C = 1:

For CPYE, option A, when PSTATE.C = 0:

For CPYE, option B, when PSTATE.C = 1:

Integer
(FEAT_MOPS)

313029282726252423222120191817161514131211109876543210
sz011101op10Rs000001RnRd
o0op2

Encoding for the Prologue variant

Applies when (op1 == 00)

CPYP [<Xd>]!, [<Xs>]!, <Xn>!

Encoding for the Main variant

Applies when (op1 == 01)

CPYM [<Xd>]!, [<Xs>]!, <Xn>!

Encoding for the Epilogue variant

Applies when (op1 == 10)

CPYE [<Xd>]!, [<Xs>]!, <Xn>!

Decode for all variants of this encoding

if !IsFeatureImplemented(FEAT_MOPS) || sz != '00' then EndOfDecode(Decode_UNDEF); CPYParams memcpy; memcpy.d = UInt(Rd); memcpy.s = UInt(Rs); memcpy.n = UInt(Rn); constant bits(4) options = op2; constant boolean rnontemporal = options<3> == '1'; constant boolean wnontemporal = options<2> == '1'; case op1 of when '00' memcpy.stage = MOPSStage_Prologue; when '01' memcpy.stage = MOPSStage_Main; when '10' memcpy.stage = MOPSStage_Epilogue; otherwise SEE "Memory Copy and Memory Set";

For information about the CONSTRAINED UNPREDICTABLE behavior of this instruction, see Architectural Constraints on UNPREDICTABLE behaviors, and particularly Memory Copy and Memory Set CPY* and Crossing a page boundary with different memory types or Shareability attributes.

Assembler Symbols

<Xd>

For the "Prologue" variant: is the 64-bit name of the general-purpose register that holds the destination address and is updated by the instruction, encoded in the "Rd" field.

For the "Epilogue" and "Main" variants: is the 64-bit name of the general-purpose register that holds an encoding of the destination address, encoded in the "Rd" field.

<Xs>

For the "Prologue" variant: is the 64-bit name of the general-purpose register that holds the source address and is updated by the instruction, encoded in the "Rs" field.

For the "Epilogue" and "Main" variants: is the 64-bit name of the general-purpose register that holds an encoding of the source address, encoded in the "Rs" field.

<Xn>

For the "Prologue" variant: is the 64-bit name of the general-purpose register that holds the number of bytes to be transferred and is updated by the instruction to encode the remaining size and destination, encoded in the "Rn" field.

For the "Main" variant: is the 64-bit name of the general-purpose register that holds an encoding of the number of bytes to be transferred, encoded in the "Rn" field.

For the "Epilogue" variant: is the 64-bit name of the general-purpose register that holds an encoding of the number of bytes to be transferred and is set to zero on completion of the instruction, encoded in the "Rn" field.

Operation

CheckMOPSEnabled(); CheckCPYConstrainedUnpredictable(memcpy.n, memcpy.d, memcpy.s); memcpy.nzcv = PSTATE.<N,Z,C,V>; memcpy.toaddress = X[memcpy.d, 64]; memcpy.fromaddress = X[memcpy.s, 64]; if memcpy.stage == MOPSStage_Prologue then memcpy.cpysize = UInt(X[memcpy.n, 64]); else memcpy.cpysize = SInt(X[memcpy.n, 64]); memcpy.implements_option_a = CPYOptionA(); constant boolean rprivileged = (if options<1> == '1' then AArch64.IsUnprivAccessPriv() else PSTATE.EL != EL0); constant boolean wprivileged = (if options<0> == '1' then AArch64.IsUnprivAccessPriv() else PSTATE.EL != EL0); constant AccessDescriptor raccdesc = CreateAccDescMOPS(MemOp_LOAD, rprivileged, rnontemporal); constant AccessDescriptor waccdesc = CreateAccDescMOPS(MemOp_STORE, wprivileged, wnontemporal); if memcpy.stage == MOPSStage_Prologue then if memcpy.cpysize > ArchMaxMOPSCPYSize then memcpy.cpysize = ArchMaxMOPSCPYSize; memcpy.forward = IsMemCpyForward(memcpy); if memcpy.implements_option_a then memcpy.nzcv = '0000'; if memcpy.forward then // Copy in the forward direction offsets the arguments. memcpy.toaddress = memcpy.toaddress + memcpy.cpysize; memcpy.fromaddress = memcpy.fromaddress + memcpy.cpysize; memcpy.cpysize = 0 - memcpy.cpysize; else if !memcpy.forward then // Copy in the reverse direction offsets the arguments. memcpy.toaddress = memcpy.toaddress + memcpy.cpysize; memcpy.fromaddress = memcpy.fromaddress + memcpy.cpysize; memcpy.nzcv = '1010'; else memcpy.nzcv = '0010'; memcpy.stagecpysize = MemCpyStageSize(memcpy); if memcpy.stage != MOPSStage_Prologue then memcpy.forward = memcpy.cpysize < 0 || (!memcpy.implements_option_a && memcpy.nzcv<3> == '0'); CheckMemCpyParams(memcpy, options); integer copied; boolean iswrite; AddressDescriptor memaddrdesc; PhysMemRetStatus memstatus; boolean fault = FALSE; MOPSBlockSize B; if memcpy.implements_option_a then while memcpy.stagecpysize != 0 && !fault do // IMP DEF selection of the block size that is worked on. While many // implementations might make this constant, that is not assumed. B = CPYSizeChoice(memcpy); if memcpy.forward then assert B <= -1 * memcpy.stagecpysize; (copied, iswrite, memaddrdesc, memstatus) = MemCpyBytes( memcpy.toaddress + memcpy.cpysize, memcpy.fromaddress + memcpy.cpysize, memcpy.forward, B, raccdesc, waccdesc); if copied != B then fault = TRUE; else memcpy.cpysize = memcpy.cpysize + B; memcpy.stagecpysize = memcpy.stagecpysize + B; else assert B <= memcpy.stagecpysize; memcpy.cpysize = memcpy.cpysize - B; memcpy.stagecpysize = memcpy.stagecpysize - B; (copied, iswrite, memaddrdesc, memstatus) = MemCpyBytes( memcpy.toaddress + memcpy.cpysize, memcpy.fromaddress + memcpy.cpysize, memcpy.forward, B, raccdesc, waccdesc); if copied != B then fault = TRUE; memcpy.cpysize = memcpy.cpysize + B; memcpy.stagecpysize = memcpy.stagecpysize + B; else while memcpy.stagecpysize > 0 && !fault do // IMP DEF selection of the block size that is worked on. While many // implementations might make this constant, that is not assumed. B = CPYSizeChoice(memcpy); assert B <= memcpy.stagecpysize; if memcpy.forward then (copied, iswrite, memaddrdesc, memstatus) = MemCpyBytes(memcpy.toaddress, memcpy.fromaddress, memcpy.forward, B, raccdesc, waccdesc); if copied != B then fault = TRUE; else memcpy.fromaddress = memcpy.fromaddress + B; memcpy.toaddress = memcpy.toaddress + B; else (copied, iswrite, memaddrdesc, memstatus) = MemCpyBytes(memcpy.toaddress - B, memcpy.fromaddress - B, memcpy.forward, B, raccdesc, waccdesc); if copied != B then fault = TRUE; else memcpy.fromaddress = memcpy.fromaddress - B; memcpy.toaddress = memcpy.toaddress - B; if !fault then memcpy.cpysize = memcpy.cpysize - B; memcpy.stagecpysize = memcpy.stagecpysize - B; UpdateCpyRegisters(memcpy, fault, copied); if fault then if IsFault(memaddrdesc) then AArch64.Abort(memaddrdesc.fault); else constant AccessDescriptor accdesc = if iswrite then waccdesc else raccdesc; HandleExternalAbort(memstatus, iswrite, memaddrdesc, B, accdesc); if memcpy.stage == MOPSStage_Prologue then PSTATE.<N,Z,C,V> = memcpy.nzcv;

Base Instructions
SIMD&FP Instructions
SVE Instructions
SME Instructions
Index by Encoding
Shared Pseudocode
Proprietary Notice

Internal version only: aarchmrs v2024-12_rel, pseudocode v2024-12_rel ; Build timestamp: 2024-12-15T22:18

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