CPU: all which supported IA MMX:
Pentium (P55C only), Pentium (tm) Pro (P6) future models
Type of Instruction: User

Instruction: PUNPCKHBW dest,src


dest[63..56] <- src[63..56]
dest[55..48] <- dest[63..56]
dest[47..40] <- src[55..48]
dest[39..32] <- dest[55..48]
dest[31..24] <- src[47..40]
dest[23..16] <- dest[47..40]
dest[15..8] <- src[39..32]
dest[7..0] <- dest[39..32]

Note: This instruction unpack and interleave the high-order data elements
of the destination and source operands into the destination operand.
The low-order data elements are ignored.
When unpacking from a memory operand, the full 64-bit operand is
accessed from memory. The instruction uses only the high-order 32 bits.
If the source operand is all zeros, the result is a zero extension of
the high-order elements of the destination operand. When using
PUNPCKHBW instruction the bytes are zero extended, or unpacked into
unsigned words.

Flags affected: None


RM PM VM SMM Description
#GP(0) If Illegal memory operand's EA in CS,DS,ES,FS,GS
#SS(0) If illegal memory operand's EA in SS
#PF(fcode) If page fault
#AC #AC If unaligned memory reference then alignment
check enabled and in ring 3.
#UD #UD #UD #UD If CR0.EM = 1
#NM #NM #NM #NM If CR0.TS = 1
#MF #MF #MF #MF If pending FPU Exception
#13 #13 If any part of the the operand lies outside of
the EA space from 0 to FFFFH
COP & Times:

PUNPCKHBW mm,mm/m64 0FH 68H PostByte

P55C: n/a
future P6: n/a

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