Intel 64 and IA-32 Architectures Software Developers Manual Volume 1, Basic Architecture

Vol. 1 9-1
CHAPTER 9
PROGRAMMING WITH INTEL® MMX™ TECHNOLOGY
The Intel MMX technology was introduced into the IA-32 architecture in the
Pentium II processor family and Pentium processor with MMX technology. The exten-
sions introduced in MMX technology support a single-instruction, multiple-data
(SIMD) execution model that is designed to accelerate the performance of advanced
media and communications applications.
This chapter describes MMX technology.
9.1 OVERVIEW OF MMX TECHNOLOGY
MMX technology defines a simple and flexible SIMD execution model to handle 64-bit
packed integer data. This model adds the following features to the IA-32 architec-
ture, while maintaining backwards compatibility with all IA-32 applications and
operating-system code:
• Eight new 64-bit data registers, called MMX registers
• Three new packed data types:
— 64-bit packed byte integers (signed and unsigned)
— 64-bit packed word integers (signed and unsigned)
— 64-bit packed doubleword integers (signed and unsigned)
• Instructions that support the new data types and to handle MMX state
management
• Extensions to the CPUID instruction
MMX technology is accessible from all the IA32-architecture execution modes
(protected mode, real address mode, and virtual 8086 mode). It does not add any
new modes to the architecture.
The following sections of this chapter describe MMX technology’s programming envi-
ronment, including MMX register set, data types, and instruction set. Additional
instructions that operate on MMX registers have been added to the IA-32 architec-
ture by the SSE/SSE2 extensions.
For more information, see:
• Section 10.4.4, “SSE 64-Bit SIMD Integer Instructions,” describes MMX instruc-
tions added to the IA-32 architecture with the SSE extensions.
• Section 11.4.2, “SSE2 64-Bit and 128-Bit SIMD Integer Instructions,” describes
MMX instructions added to the IA-32 architecture with SSE2 extensions.
• Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volumes
2A & 2B, give detailed descriptions of MMX instructions.