RealView Compilation Tools Compiler Reference Guide - ARM ...

Compiler-specific Features
Example
int foo(void)
{
int loc=0xff;
return(__swp(0x20, (volatile int *)loc));
}
Compiling this code produces
||foo|| PROC
MOV r1, #0xff
MOV r0, #0x20
SWP r0, r0, [r1]
BX lr
ENDP
See also
• SWP and SWPB on page 4-39 in the Assembler Guide.
4.7.42 __usat
This intrinsic inserts a USAT instruction into the instruction stream generated by the
compiler. It enables you to saturate an unsigned value from within your C or C++ code.
Syntax
int __usat(unsigned int val, unsigned int sat)
Where:
val
sat
Is the value to be saturated.
Is the bit position to saturate to.
usat must be in the range 0 to 31.
Return value
The __usat intrinsic returns val saturated to the unsigned range 0 ≤ x ≤ 2 sat–1 –1.
Errors
The compiler does not recognize the __usat intrinsic when compiling for a target that
does not support the USAT instruction. The compiler generates either a warning or an
error in this case.
ARM DUI 0348A Copyright © 2007, 2010 ARM Limited. All rights reserved. 4-93
Non-Confidential