MMX instruction that compares 2 64 bit values for equality, bytewise.

Note: unlike integer comparison operators, MMX comparison operators do not affect any flags.

Each byte of the destination register is set to all 1's if it was equal to the corresponding byte of the source register. Otherwise, it is set to all zeros.

Comparing a register with itself will always produce all 1's.

See also: PCMPGTB, PCMPEQW, PCMPEQD