ARM Compiler toolchain v4.1 for µVision Using the Compiler

Using the Inline and Embedded Assemblers of the ARM Compiler
7.33 Effect of compiler ARM and Thumb states on embedded assembler
The initial state of the embedded assembler, ARM or Thumb state, is determined by the initial
state of the compiler, as specified on the command line. This means that:
• if the compiler starts in ARM state, the embedded assembler uses --arm
• if the compiler starts in Thumb state, the embedded assembler uses --thumb.
The embedded assembler state at the start of each function is as set by the invocation of the
compiler, as modified by #pragma arm and #pragma thumb pragmas.
You can change the state of the embedded assembler within a function by using explicit ARM,
THUMB, or CODE16 directives in the embedded assembler function. Such a directive within an __asm
function does not affect the ARM or Thumb state of subsequent __asm functions.
If you are compiling for a Thumb-2 capable processor, you can use Thumb-2 instructions when
in Thumb state.
7.33.1 See also
Concepts
• Compiler support for embedded assembler on page 7-36.
ARM DUI 0375C Copyright © 2007-2008, 2011 ARM. All rights reserved. 7-39
ID061811
Non-Confidential