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ARM Compiler armasm User Guide : CRC32CB, CRC32CH, CRC32CW, CRC32CX

CRC32CB, CRC32CH, CRC32CW, CRC32CX

CRC32C checksum.

Syntax

CRC32CB Wd, Wn, Wm ; Wd = CRC32C(Wn, Rm[7:0])

CRC32CH Wd, Wn, Wm ; Wd = CRC32C(Wn, Rm[15:0])

CRC32CW Wd, Wn, Wm ; Wd = CRC32C(Wn, Rm[31:0])

CRC32CX Wd, Wn, Xm ; Wd = CRC32C(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

CRC32 checksum performs a cyclic redundancy check (CRC) calculation on a value held in a general-purpose register. It 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 0x1EDC6F41 is used for the CRC calculation.

In ARMv8-A, this is an OPTIONAL instruction.

Note

ID_AA64ISAR0_EL1.CRC32 indicates whether this instruction is supported. See ID_AA64ISAR0_EL1 in the ARMv8-A Architecture Reference Manual.

Wd = CRC32C(Wn, Rmn:0) // n = 7, 15, 31, 63.

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