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SIMD ISAReturn TypeNameArgumentsInstruction Group
Neonuint32_t__crc32cw(uint32_t a, uint32_t b)Cryptography / CRC32
Description
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.
Results
Wd result
This intrinsic compiles to the following instructions:

CRC32CW Wd,Wn,Wm

Argument Preparation
a register: Wnb register: Wm
Architectures
A32, A64

Operation

bits(32)      acc     = X[n];   // accumulator
bits(size)    val     = X[m];   // input value
bits(32)      poly    = (if crc32c then 0x1EDC6F41 else 0x04C11DB7)<31:0>;

bits(32+size) tempacc = BitReverse(acc) : Zeros(size);
bits(size+32) tempval = BitReverse(val) : Zeros(32);

// Poly32Mod2 on a bitstring does a polynomial Modulus over {0,1} operation
X[d] = BitReverse(Poly32Mod2(tempacc EOR tempval, poly));