MMX instruction to pack signed words into signed bytes.

Takes either two MMX registers or an MMX register (source) and a 64 bit memory location (destination) as operands.

The high 32 bits of the destination register are filled with the 4 original words of the destination register, packed down to bytes. Word values over 127 are clamped to 127; word values under -128 are clamped to -128. The low 32 bits of the destination register are filled in the same fashion, but with the source words from the source operand.

Compare PACKSSDW, PACKUSWB.

Log in or register to write something here or to contact authors.