HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens

           MSC: unsigned _control87( unsigned new, unsigned mask )

       - prototype in float.h

       - used to change floating point handling and exception masking
       - new = contains corresponding bit values for any bit set in "mask"
               to be moved into the coprocessor control word
       - mask  = zero; gets floating-point coprocessor control word
               = non-zero; if any bit is set, the corresponding bit in
                 "new" is moved into the coprocessor control word
       - returns floating-point coprocessor control word
       - default control word is the logical OR of: IC_AFFINE, RC_NEAR,

       Control Word Mask and Bits

       MCW_EM          interrupt exception control
       MCW_IC          infinity control
       MCW_RC          rounding control
       MCW_PC          precision control

       Exception Masks

       EM_INVALID      invalid
       EM_DENORMAL     denormal
       EM_ZERODIVIDE   zero divide
       EM_OVERFLOW     overflow
       EM_UNDERFLOW    underflow
       EM_INEXACT      inexact (precision)

       Infinity Control

       IC_AFFINE       affine
       IC_PROJECTIVE   projective

       Rounding Control

       RC_CHOP         truncate
       RC_UP           round up
       RC_DOWN         round down
       RC_NEAR         near

       Precision Control

       PC_24           24 bits precision
       PC_53           53 bits precision
       PC_64           64 bits precision

       User Status Word Bits

       SW_INVALID      invalid
       SW_DENORMAL     denormal
       SW_ZERODIVIDE   zero divide
       SW_OVERFLOW     overflow
       SW_UNDERFLOW    underflow
       SW_INEXACT      inexact precision

       Invalid Subconditions (if SW_INVALID)

       SW_UNEMULATED   unemulated instruction
       SW_SQRTNEG      square root of a neg number
       SW_STACKOVERFLOW  FP stack overflow
       SW_STACKUNDERFLOW FP stack underflow

       Floating Point Errors


       - see   _clear87()   _status87()

Esc or Alt-X to exit _control87 Home/PgUp/PgDn/End ←↑↓→