MMX(TM) Technology Intrinsics on Itanium® Architecture

MMX™ technology intrinsics provide access to the MMX technology instruction set on Itanium®-based systems. To provide source compatibility with the IA-32 architecture, these intrinsics are equivalent both in name and functionality to the set of IA-32-based MMX intrinsics.

The prototypes for MMX technology intrinsics are in the mmintrin.h header file.

Data Types

The C data type __m64 is used when using MMX technology intrinsics. It can hold eight 8-bit values, four 16-bit values, two 32-bit values, or one 64-bit value.

The __m64 data type is not a basic ANSI C data type. Therefore, observe the following usage restrictions:

• Use the new data type only on the left-hand side of an assignment, as a return value, or as a parameter. You cannot use it with other arithmetic expressions (" + ", " - ", and so on).
• Use the new data type as objects in aggregates, such as unions, to access the byte elements and structures; the address of an __m64 object may be taken.
• Use new data types only with the respective intrinsics described in this documentation.

For complete details of the hardware instructions, see the Intel® Architecture MMX™ Technology Programmer's Reference Manual. For descriptions of data types, see the Intel® Architecture Software Developer's Manual, Volume 2.