PC Extra Super CD 1998 January/PCPLUS131.iso/DJGPP/V2/DJLSR201.ZIP/src/libc/pc_hw/fpu/cntrl87.txh

Text File | 1995-07-10 | 1.5 KB | 41 lines

@c ----------------------------------------------------------------------
@node _control87, cpu
@subheading Syntax

@example
#include <float.h>

unsigned int _control87(unsigned int newcw, unsigned int mask);
@end example

@subheading Description

Sets or resets bits in the FPU's control register.  The bits are
defined by macros in float.h, and by this table:

@example
---- ---- --XX XXXX = MCW_EM - exception masks (1=handle exception internally, 0=fault)
---- ---- ---- ---X = EM_INVALID - invalid operation
---- ---- ---- --X- = EM_DENORMAL - denormal operand
---- ---- ---- -X-- = EM_ZERODIVIDE - divide by zero
---- ---- ---- X--- = EM_OVERFLOW - overflow
---- ---- ---X ---- = EM_UNDERFLOW - underflow
---- ---- --X- ---- = EM_INEXACT - rounding was required
---- --XX ---- ---- = MCW_PC - precision control
---- --00 ---- ---- = PC_24 - single precision
---- --10 ---- ---- = PC_53 - double precision
---- --11 ---- ---- = PC_64 - extended precision
---- XX-- ---- ---- = MCW_RC - rounding control
---- 00-- ---- ---- = RC_NEAR - round to nearest
---- 01-- ---- ---- = RC_DOWN - round towards -Inf
---- 10-- ---- ---- = RC_UP - round towards +Inf
---- 11-- ---- ---- = RC_CHOP - round towards zero
---X ---- ---- ---- = MCW_IC - infinity control (obsolete, always affine)
---0 ---- ---- ---- = IC_AFFINE - -Inf < +Inf
---1 ---- ---- ---- = IC_PROJECTIVE - -Inf == +Inf
@end example

@subheading Return Value

The previous control word.