fpi(3) — bsd — mips UMIPS RISC/os 5.01



FPI(3-BSD)          RISC/os Reference Manual           FPI(3-BSD)



NAME
     fpi - floating-point interrupt analysis

SYNOPSIS
     #include <fpi.h>

     void fpi()

     void printfpicounts()
     int fpicounts[];

     char *fpilist[];

DESCRIPTION
     MIPS floating-point units generate floating-point interrupts
     for some classes of operations that occur with low fre-
     quency.  In these cases the system software then emulates
     the operation in software.  As a program takes floating-
     point interrupts its performance degrades since the opera-
     tions are emulated in software.  The routines and counters
     described here are used to analyze the causes of floating-
     point interrupts.

     The routine fpi makes a fp_sigintr(2) (for -systype bsd) or
     sysmips(2) [MIPS_FPISGINT] (for -systype svr3) system call
     to cause floating-point interrupts to generate a SIGFPE.  It
     also sets up a special signal handler for SIGFPE's.  On a
     floating-point interrupt that signal handler determines the
     precise cause of the interrupt and increments the appropri-
     ate counter in fpi_counts[].

     The routine printfpi_counts prints out the value of the
     counters and their description on stderr as in the following
     example:
             source signaling NaN = 0
             source quiet NaN = 10
             source denormalized value = 23
             move of zero = 83
             negate of zero = 84
             implemented only in software = 5
             invalid operation = 96
             divide by zero = 3837
             destination overflow = 398
             destination underflow = 489
     The constants in the file <fpi.h> along the counters,
     fpi_counts[], and the descriptive strings, fpi_list[], can
     also be used to format messages.

LIMITATIONS
     fpi can't be used with programs that normally generate
     SIGFPE's.




                        Printed 11/19/92                   Page 1



FPI(3-BSD)          RISC/os Reference Manual           FPI(3-BSD)



ALSO SEE
     R2010 Floating Point Coprocessor Architecture
     R2360 Floating Point Board Product Description
     fp_sigintr(2).  sysmips(2) [MIPS_FPISGINTR].



















































 Page 2                 Printed 11/19/92

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