Subversion Repositories openrisc_me

@node machine,,syscalls,Top

@chapter NEC V70 Specific Functions

The NEC V70 has machine instructions for fast IEEE floating-point

arithmetic, including operations normally provided by the library.

When you use the @file{/usr/include/fastmath.h} header file, the

names of several library math functions are redefined to call the

@code{fastmath} routine (using the corresponding V70 machine instructions)

whenever possible.

For example,

@example

#include <fastmath.h>

double sqsin(x)

double x;

@{

  return sin(x*x);

@}

@end example

expands into the code

@example

@dots{}

double sqsin(x)

double x;

@{

  return fast_sin(x*x);

@}

@end example

The library has an entry @code{fast_sin} which uses the machine

instruction @code{fsin.l} to perform the operation.  Note that the

built-in instructions cannot call @code{matherr} or set @code{errno}

in the same way that the C coded functions do.  Refer to a V70

instruction manual to see how errors are generated and handled.

Also, the library provides true @code{float} entry points.  The

@code{fast_sinf} entry point really performs a @code{fsin.s}

operation.  Because of this, the instructions are only useful when

using code compiled with an ANSI C compiler.  The prototypes

and definitions for the floating-point versions of the math library

routines are only defined if compiling a module with an ANSI C

compiler.

@page

@section Entry points

The functions provided by @file{fastmath.h} are

@example

 double fast_sin(double);       /*      fsin.l */

 double fast_cos(double);       /*      fcos.l */

 double fast_tan(double);       /*      ftan.l */

 double fast_asin(double);      /*      fasin.l */

 double fast_acos(double);      /*      facos.l */

 double fast_atan(double);      /*      fatan.l */

 double fast_sinh(double);      /*      fsinh.l */

 double fast_cosh(double);      /*      fcosh.l */

 double fast_tanh(double);      /*      ftanh.l */

 double fast_asinh(double);     /*      fasinh.l */

 double fast_acosh(double);     /*      facosh.l */

 double fast_atanh(double);     /*      fatanh.l */

 double fast_fabs(double);      /*      fabs.l */

 double fast_sqrt(double);      /*      fsqrt.l */

 double fast_exp2(double);      /*      fexp2.l */

 double fast_exp10(double);     /*      fexp10.l */

 double fast_expe(double);      /*      fexpe.l */

 double fast_log10(double);     /*      flog10.l */

 double fast_log2(double);      /*      flog2.l */

 double fast_loge(double);      /*      floge.l */

 float fast_sinf(float);        /*      fsin.s */

 float fast_cosf(float);        /*      fcos.s */

 float fast_tanf(float);        /*      ftan.s */

 float fast_asinf(float);       /*      fasin.s */

 float fast_acosf(float);       /*      facos.s */

 float fast_atanf(float);       /*      fatan.s */

 float fast_sinhf(float);       /*      fsinh.s */

 float fast_coshf(float);       /*      fcosh.s */

 float fast_tanhf(float);       /*      ftanh.s */

 float fast_asinhf(float);      /*      fasinh.s */

 float fast_acoshf(float);      /*      facosh.s */

 float fast_atanhf(float);      /*      fatanh.s */

 float fast_fabsf(float);       /*      fabs.s */

 float fast_sqrtf(float);       /*      fsqrt.s */

 float fast_exp2f(float);       /*      fexp2.s */

 float fast_exp10f(float);      /*      fexp10.s */

 float fast_expef(float);       /*      fexpe.s */

 float fast_log10f(float);      /*      flog10.s */

 float fast_log2f(float);       /*      flog2.s */

 float fast_logef(float);       /*      floge.s */

@end example