MATCH : Compare 4 couples of bytes and generate a bitfield

This instruction XORs both operands and NORs the resulting 4 bytes, generating a 4-bit field that can be reused as an index.

; R1 = 34343434h (the wanted signature)
; D4 = 12345678h (some data coming from somewhere)
MATCH R1 D4 ; D4^R1= 2600624Ch -> bytemask=00FF0000h -> D4=bitmask=0100b (4)

The BMASK instruction performs the same operation but creates a bytemask instead of a bitmask.