5.50 Types of floating-point linkage

Different types of floating-point linkage provide different benefits.

The types of floating-point linkage are:

  • Software floating-point linkage.

  • Hardware floating-point linkage.

Software floating-point linkage means that the parameters and return value for a function are passed using the ARM integer registers r0 to r3 and the stack.

Hardware floating-point linkage uses the Vector Floating-Point (VFP) coprocessor registers to pass the arguments and return value.

The benefit of using software floating-point linkage is that the resulting code can be run on a processor with or without a VFP coprocessor. It is not dependent on the presence of a VFP hardware coprocessor, and it can be used with or without a VFP coprocessor present.

The benefit of using hardware floating-point linkage is that it is more efficient than software floating-point linkage, but you must have a VFP coprocessor.

Related concepts
5.41 Compiler support for floating-point arithmetic
5.42 Default selection of hardware or software floating-point support
5.43 Example of hardware and software support differences for floating-point arithmetic
5.44 Vector Floating-Point (VFP) architectures
5.45 Limitations on hardware handling of floating-point arithmetic
5.46 Implementation of Vector Floating-Point (VFP) support code
5.47 Compiler and library support for half-precision floating-point numbers
5.48 Half-precision floating-point number format
5.49 Compiler support for floating-point computations and linkage
5.51 Compiler options for floating-point linkage and computations
Related reference
5.52 Floating-point linkage and computational requirements of compiler options
5.53 Processors and their implicit Floating-Point Units (FPUs)
Related information
Procedure Call Standard for the ARM Architecture
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