For convenience, an implementation of VFP support code that can be used in your system is provided with your installation of the ARM compilation tools. The support code comprises the libraries vfpsupport.l and vfpsupport.b for emulating VFP operations bounced by the hardware. These files are located in the \lib\armlib subdirectory of your installation.

When the VFP coprocessor bounces an instruction, an Undefined Instruction exception is signaled to the processor and the VFP support code is entered through the Undefined Instruction vector. The top-level and second-level interrupt handlers perform some initial processing of the signal, for example, ensuring that the exception is not caused by an illegal instruction. The user-level interrupt handler then calls the appropriate library function in the library vfpsupport.l or vfpsupport.b to emulate the VFP operation in software.