High-Performance Embedded Computing

82 Chapter 2 CPUs

Example 2-5

Motorola AltiVec Vector Architecture

The AltiVec vector architecture [Ful98] was defined by Motorola (now Free-

scale Semiconductor) for the PowerPC architecture. AltiVec provides a 128-bit

vector unit that can be divided into operands of several sizes: four operands of

32 bits, eight operands of 16 bits, or sixteen operands of 8 bits. A register file

provides thirty-two 128-bit vectors to the vector unit. The architecture defines a

number of operations, including logical and arithmetic operands within an ele-

ment as well as inter-element operations such as permutations.

2.4.4 Thread-Level Parallelism

Processors can also ...