2.2.7. Thumb instruction set overview

The functionality of the Thumb instruction set is almost exactly a subset of the functionality of the ARM instruction set. The instruction set is optimized for production by a C or C++ compiler.

All Thumb instructions are 16 bits long and are stored halfword-aligned in memory. Because of this, the least significant bit of the address of an instruction is always zero in Thumb state. Some instructions use the least significant bit to determine whether the code being branched to is Thumb code or ARM code.

All Thumb data processing instructions:

Refer to Chapter 5 Thumb Instruction Reference for detailed information on the syntax of the Thumb instruction set, and how Thumb instructions differ from their ARM counterparts.

Copyright © 2000, 2001 ARM Limited. All rights reserved.ARM DUI 0068B
Non-Confidential