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PROGRAMMING WITH SSE3 AND SUPPLEMENTAL SSE3

12.6.6Packed Sign

There are six packed-sign instructions (represented by three mnemonics). Three operate on 128-bit operands and three operate on 64-bit operands. The widths of each data element for these instructions are 8 bit, 16 bit or 32 bit signed integers.

PSIGNB/W/D negates each signed integer element of the destination operand if the sign of the corresponding data element in the source operand is less than zero.

12.6.7Packed Align Right

There are two packed-align-right instructions (represented by one mnemonic). One operates on 128-bit operands and the other operates on 64-bit operands. These instructions concatenate the destination and source operand into a composite, and extract the result from the composite according to an immediate constant.

PALIGNR’s source operand is appended after the destination operand forming an intermediate value of twice the width of an operand. The result is extracted from the intermediate value into the destination operand by selecting the 128-bit or 64-bit value that are right-aligned to the byte offset specified by the immediate value.

12.7WRITING APPLICATIONS WITH SSSE3 EXTENSIONS

The following sections give guidelines for writing application programs and oper- ating-system code that use SSSE3 instructions.

12.7.1Guidelines for Using SSSE3 Extensions

The following guidelines describe how to maximize the benefits of using SSSE3 extensions:

Ensure that the processor supports SSSE3 extensions.

Ensure that your operating system supports SSE/SSE2/SSE3/SSSE3 extensions. (Operating system support for the SSE extensions implies support for SSE2, the x87, SIMD instructions of SSE3, and SSSE3.)

Employ the optimization and scheduling techniques described in the Intel® 64 and IA-32 Architectures Optimization Reference Manual (see Section 1.4, “Related Literature”).

Vol. 1 12-13

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