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CRC32B, CRC32H, CRC32W, CRC32X

CRC32 checksum performs a cyclic redundancy check (CRC) calculation on a value held in a general-purpose register.

Syntax

CRC32B Wd, Wn, Wm ; Wd = CRC32(Wn, Rm[<7:0>])

CRC32H Wd, Wn, Wm ; Wd = CRC32(Wn, Rm[<15:0>])

CRC32W Wd, Wn, Wm ; Wd = CRC32(Wn, Rm[<31:0>])

CRC32X Wd, Wn, Xm ; Wd = CRC32(Wn, Rm[<63:0>])

Where:

Wm
Is the 32-bit name of the general-purpose data source register.
Xm
Is the 64-bit name of the general-purpose data source register.
Wd
Is the 32-bit name of the general-purpose accumulator output register.
Wn
Is the 32-bit name of the general-purpose accumulator input register.

Operation

This instruction takes an input CRC value in the first source operand, performs a CRC on the input value in the second source operand, and returns the output CRC value. The second source operand can be 8, 16, 32, or 64 bits. To align with common usage, the bit order of the values is reversed as part of the operation, and the polynomial 0x04C11DB7 is used for the CRC calculation.

Note

ID_AA64ISAR0_EL1.CRC32 indicates whether this instruction is supported. See ID_AA64ISAR0_EL1 in the Arm® Architecture Reference Manual Arm®v8, for Arm®v8‑A architecture profile.

Wd = CRC32(Wn, Rm<n:0>) // n = 7, 15, 31, 63.

Architectures supported

Supported in architecture Arm®v8.1 and later. Optionally supported in Armv8‑A.

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