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Compiler-specific Features
Note
This keyword has the #pragma equivalent #pragma __softfp_linkage.
Usage
Calls to the function pass floating-point arguments in integer registers. If the result is a
floating-point value, the value is returned in integer registers. This duplicates the
behavior of compilation targeting software floating-point.
This keyword enables the same library to be used by sources compiled to use hardware
and software floating-point.
Note
In C++, if a virtual function qualified with the __softfp keyword is to be overridden, the
overriding function must also be declared as __softfp. If the functions do not match, the
compiler generates an error.
See also
• --fpu=name on page 2-62
• #pragma softfp_linkage, #pragma no_softfp_linkage on page 4-70
• Floating-point computations and linkage on page 5-37 in the Compiler User
Guide.
4.1.15 __svc
The __svc keyword declares a SuperVisor Call (SVC) function taking up to four
integer-like arguments and returning up to four results in a value_in_regs structure.
__svc is a function qualifier. It affects the type of a function.
Syntax
__svc(int svc_num) return-type function-name([argument-list]);
Where:
svc_num
Is the immediate value used in the SVC instruction.
It is an expression evaluating to an integer in the range:
• 0 to 2 24 –1 (a 24-bit value) in an ARM instruction
• 0-255 (an 8-bit value) in a 16-bit Thumb instruction.
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