9-16
PROGRAMMING WITH THE STREAMING SIMD EXTENSIONS
The UNPCKLPS (Unpacked low packed, single-precision, floating-point) instruction performs
an interleaved unpack of the low-order data elements of first and second packed, single-preci-
sion, floating-point operands. It ignores the higher half part of the sources (Figure 9-9). When
unpacking from a memory operand, the full 128-bit operand is accessed from memory, but only
the low order 64 bits are utilized by the instruction.
9.3.8.State Management Instructions
The LDMXCSR (Load SIMD Floating-Point Control and Status Register) instruction loads the
SIMD floating-point control and status register from memory. STMXCSR (Store SIMD
Figure 9-8. Unpack High Operation
Figure 9-9. Unpack Low Operation
X4
X3
X2
X1
Y4
Y3
Y2
Y1
Y4
X4
Y3
X3
X4
X3
X2
X1
Y4
Y3
Y2
Y1
Y2
X2
Y1
X1
