Floating-Point Support (Windows Embedded CE 6.0)

Article
01/05/2012

1/5/2010

Many Microsoft run-time library functions require floating-point support from a math coprocessor or from the floating-point libraries that accompany the compiler. Floating-point support functions are loaded only if required.

When you use a floating-point type specifier in the format string of a call to a function in the printf or scanf family, you must specify a floating-point value or a pointer to a floating-point value in the argument list to tell the compiler that floating-point support is required.

The math functions in the Microsoft run-time library handle exceptions the same way that UNIX V math functions do.

The Microsoft run-time library sets the default internal precision of the math coprocessor (or emulator) to 64 bits. This default applies only to the internal precision at which all intermediate calculations are performed; it does not apply to the size of arguments, return values, or variables.

You can override this default and set the chip (or emulator) back to 80-bit precision by linking your program with LIB/FP10.OBJ.

On the linker command line, FP10.OBJ must appear before LIBC.LIB, LIBCMT.LIB, or MSVCRT.LIB.

For detailed reference information about the CRT functions, see Alphabetical Function Reference (CRT).

Routine	Use
abs	Returns absolute value of int
acos	Calculates arccosine
asin	Calculates arcsine
atan, atan2	Calculates arctangent
atof	Converts character string to double-precision floating-point value
_cabs	Finds absolute value of complex number
ceil, ceilf	Finds integer ceiling
_chgsign	Reverses sign of double-precision floating-point argument
clearerr	Clears error. This function has been deprecated because a more secure version, clearerr_s, is available.
clearerr_s	Resets the error indicator for a stream. Security-enhanced version of clearerr.
_controlfp	Gets and sets the floating-point control word. This function has been deprecated because a more secure version, _controlfp_s, is available.
controlfp_s	Gets and sets the floating-point control word. Security-enhanced version of deprecated function _controlfp. Returns error for bad parameters.
_copysign	Returns one value with sign of another
cos	Calculates cosine
cosh	Calculates hyperbolic cosine
div	Divides one integer by another, returning quotient and remainder
_ecvt	Converts double to character string of specified length. This function has been deprecated because a more secure version, _evct_s, is available.
_ecvt_s	Converts a double number to a string. Security-enhanced version of deprecated function _ecvt. Validates parameters and sets errno. Template overload available.
exp	Calculates exponential function
fabs, fabsf	Finds absolute value
_fcvt	Converts double to string with specified number of digits following decimal point. This function has been deprecated because a more secure version, _fvct_s, is available.
_fcvt_s	Converts a floating-point number to a string. Security-enhanced version of deprecated function _fcvt. Validates parameters and sets errno. Template overload available.
_finite	Determines whether given double-precision floating-point value is finite
floor, floorf	Finds largest integer less than or equal to argument
fmod, fmodf	Finds floating-point remainder
_fpclass	Returns status word containing information on floating-point class
_fpieee_flt	Invokes user-defined trap handler for IEEE floating-point exceptions
_fpreset	Reinitializes floating-point math package
frexp	Calculates exponential value
_gcvt	Converts floating-point value to character string. This function has been deprecated because a more secure version, _gvct_s, is available.
_gcvt_s	Converts a floating-point value to a string. Security-enhanced version of deprecated function _gcvt. Validates parameters and sets errno. Template overload available.
_hypot	Calculates hypotenuse of right triangle
_isnan	Checks given double-precision floating-point value for not a number (NaN)
_j0, _j1, _jn	Calculates Bessel functions _j0, _j1, and _jn
labs	Returns absolute value of long
ldexp	Calculates product of argument and 2 to specified power
ldiv	Divides one long integer by another, returning quotient and remainder
log, log10	Calculates logarithm
_logb	Extracts exponential value of double-precision floating-point argument
_lrotl, _lrotr	Shifts unsigned long int left (_lrotl) or right (_lrotr)
modf	Splits argument into integer and fractional parts
_nextafter	Returns next representable neighbor
pow	Calculates value raised to a power
rand	Gets pseudorandom number
rand_s	Generates a pseudorandom number. Security-enhanced version of rand.
_rotl, _rotr	Shifts unsigned int left (_rotl) or right (_rotr)
_scalb	Scales argument by power of 2
sin	Calculates sine
sinh	Calculates hyperbolic sine
sqrt	Finds square root
srand	Initializes pseudorandom series
_statusfp	Gets floating-point status word
strtod	Converts character string to double-precision value
tan	Calculates tangent
tanh	Calculates hyperbolic tangent
_y0, _y1, _yn	Calculates Bessel functions _yo, _y1, and _yn

Floating-Point Support (Windows Embedded CE 6.0)

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Concepts

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