ID Number: Q43276
1.03 1.04 2.03 2.10 3.00 3.10
WINDOWS
Summary:
When an application for Microsoft Windows is run on a machine with a
math coprocessor, the application can use inline floating-point
instructions to take the fullest advantage of the hardware.
More Information:
Specifying the -FPi option on the C compiler command line causes the
Microsoft C optimizing compiler to produce inline 80x87 math
coprocessor code for any floating-point math operation. If this code
is linked with the WIN87EM.LIB library and a math coprocessor is
present in the system at run time, the application will use the inline
floating-point instructions for its math operations. If no coprocessor
is available at run time, code in the emulator library evaluates
floating-point expressions.
An application compiled for the MS-DOS environment with the -FPi
option checks for the coprocessor at run time and modifies its code
accordingly: if there is a coprocessor, it uses inline floating-point
instructions; if there is no coprocessor, it calls software routines
to emulate the coprocessor.
In the Windows environment, these run-time modifications are not
performed because the Windows kernel fixes up the floating point
references as it loads the application's code segments (the kernel is
aware of the presence or absence of the numeric coprocessor). This
means that an application for the Windows environment compiled with
the -FPi option will perform direct, inline floating-point
instructions without run-time coprocessor-checking. Consequently,
there is no need to link in the Microsoft C Compiler inline floating-
point module, which removes the run-time coprocessor-checking.
Additional reference words: 1.03 1.04 2.03 2.10 3.00 3.10 1.x 2.x