_fpreset

Remonter à float.h - Index

Header File

float.h

Category

Math Routines

Prototype

void _fpreset(void);

Description

Reinitializes floating-point math package.

_fpreset reinitializes the floating-point math package. This function is usually used in conjunction with system or the exec... or spawn... functions. It is also used to recover from floating-point errors before calling longjmp.

Remarque :  If an 80x87 coprocessor is used in a program a child process (executed by the system, or by an exec... or spawn... function) might alter the parent process' floating-point state.

• If you use an 80x87 take the following precautions:
• Do not call system or an exec... or spawn... function while a floating-point expression is being evaluated.

Call _fpreset to reset the floating-point state after using system exec... or spawn... if there is any chance that the child process performed a floating-point operation with the 80x87.

Return Value

None.

Example

#include <process.h>
#include <float.h>
#include <stdio.h>

int safe_fpu_exec(wchar_t* program)
{
  /* Spawn another process with NOWAIT flag */
  int pid = _wspawnl(P_NOWAIT, program, NULL);
  int exitCode;

  /* Check for error */
  if (pid == -1)
    return -1;

  /* Wait for the application to finish */
  cwait(&exitCode, pid, 0);

  /* Reset the FPU state since the child process might have altered it */
  _fpreset();

  return exitCode;
}

Portability

POSIX	Win32	ANSI C	ANSI C++
	+