math.cpp

MONA是为数不多的C++语言编写的一个很小的操作系统

/*!
  \file   math.cpp
  \brief  math

  Copyright (c) 2002-2004 Higepon

  $Revision: 1.6 $
  $Date: 2004/09/01 14:10:46 $
*/

#include <monalibc/math.h>

double sin(double angle)
{
    double result;
    asm volatile ("fsin" : "=t"(result) : "0"(angle));
    return result;
}

double cos(double angle)
{
    double result;
    asm volatile ("fcos" : "=t"(result) : "0"(angle));
    return result;
}

double tan(double angle)
{
    double result;
    asm volatile ("fptan" : "=t"(result) : "0"(angle));
    return result;
}

double sqrt(double num)
{
    double result;
    asm volatile ("fsqrt" : "=t"(result) : "0"(num));
    return result;
}

double atan2(double x, double y)
{
    double result;
    asm volatile("fpatan" : "=t" (result) : "0" (x), "u" (y) : "st(1)");
    return result;
}

double atan(double x)
{
    double result;
    asm volatile("fld1; fpatan" : "=t"(result) : "0" (x) : "st(1)");
    return result;
}

/* acos = atan (sqrt(1 - x^2) / x) */
double acos(double x)
{
  double result;

  asm volatile("fld    %%st    \n"
               "fmul   %%st(0) \n"
               "fld1           \n"
               "fsubp          \n"
               "fsqrt          \n"
               "fxch   %%st(1) \n"
               "fpatan         \n"
               : "=t" (result) : "0" (x) : "st(1)");

  return result;
}

double fabs(double x)
{
    return x < 0 ? -x : x;
}

double modf(double x, double *buf)
{
    double a = fabs(x);
    int i = (int)x;

    double f = a - (double)i;

    *buf = x < 0 ? -i : i;

    return x < 0 ? -f : f;
}

double floor(double x)
{
    if (x < 0)
    {
        if (modf(-x, &x) != 0) x++;
        return -x;
    }
    modf(x, &x);
    return x;
}