Fixed point math functions
[Global/general functions]

Functions

• MG_EXPORT fixed fixsqrt (fixed x)

  Returns the non-negative square root of a fixed point value.
  

• MG_EXPORT fixed fixhypot (fixed x, fixed y)

  Returns the Euclidean distance from the origin.
  

• MG_EXPORT fixed fixatan (fixed x)

  Calculates the arc tangent of a fixed point value.
  

• MG_EXPORT fixed fixatan2 (fixed y, fixed x)

  Calculates the arc tangent of two fixed point variables.
  

• static fixed ftofix (double x)

  Converts a float point value to a fixed point value.
  

• static double fixtof (fixed x)

  Converts a fixed point value to a float point value.
  

• static fixed fixadd (fixed x, fixed y)

  Returns the sum of two fixed point values.
  

• static fixed fixsub (fixed x, fixed y)

  Subtract a fixed point value from another.
  

• static fixed fixmul (fixed x, fixed y)

  Returns the product of two fixed point values.
  

• static fixed fixdiv (fixed x, fixed y)

  Returns the quotient of two fixed point values.
  

• static int fixceil (fixed x)

  Rounds a fixed point value to the nearest integer.
  

• static fixed itofix (int x)

  Converts an integer to a fixed point value.
  

• static int fixtoi (fixed x)

  Converts an fixed point value to an integer.
  

• static fixed fixcos (fixed x)

  Returns the cosine of a fixed point.
  

• static fixed fixsin (fixed x)

  Returns the sine of a fixed point.
  

• static fixed fixtan (fixed x)

  Returns the tangent of a fixed point.
  

• static fixed fixacos (fixed x)

  Calculates and returns the arc cosine of a fixed point.
  

• static fixed fixasin (fixed x)

  Calculates and returns the arc sine of a fixed point.
  

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Detailed Description

You know that the float point mathematics routines are very expensive. If you do not want precision mathematics result, you can use fixed point. MiniGUI uses a double word (32-bit) integer to represent a fixed point ranged from -32767.0 to 32767.0, and defines some fixed point mathematics routines for your application. Some GDI functions need fixed point math routines, like Arc.

Example 1:

    /* Draw an arc from 0 radians to 1 radians */
    Arc (hdc, 100, 100, 100, 0, itofix (1));

    /* Draw an arc from 0.5 radians to 1.5 radians */
    fixed radian1 = itofix (1);
    fixed radian2 = itofix (2);
    fixed radian05 = fdiv (radian1, radian2);
    fixed radian15 = fdiv (fadd (radian1, randian2), radian2);

    Arc (hdc, 100, 100, 100, radian05, radian15);

Example 2:

void draw_arc (HDC hdc, POINT* pts)
{
            int sx = pts [0].x, sy = pts [0].y;
            int dx = pts [1].x - sx, dy = pts [1].y - sy;
            int r = sqrt (dx * dx * 1.0 + dy * dy * 1.0);
            double cos_d = dx * 1.0 / r;
            fixed cos_f = ftofix (cos_d);
            fixed ang1 = facos (cos_f);
            int r2;
            fixed ang2;

            if (dy > 0) {
                ang1 = fsub (0, ang1);
            }

            dx = pts [2].x - sx;
            dy = pts [2].y - sy;
            r2 = sqrt (dx * dx * 1.0 + dy * dy * 1.0);
            cos_d = dx * 1.0 / r2;
            cos_f = ftofix (cos_d);
            ang2 = facos (cos_f);
            if (dy > 0) {
                ang2 = fsub (0, ang2);
            }

            Arc (hdc, sx, sy, r, ang1, ang2);
}

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Function Documentation

fixed fixacos (  fixed  x  )  [inline, static]

Calculates and returns the arc cosine of a fixed point. This function calculates the arc cosine of the fixed point x; that is the value whose cosine is x. If x falls outside the range -1 to 1, this function fails and errno is set to EDOM. Returns: Returns the arc cosine in radians and the value is mathematically defined to be between 0 and PI (inclusive). See also: fixcos Definition at line 397 of file fixedmath.h.

fixed fixadd (  fixed  x, fixed  y )  [inline, static]

Returns the sum of two fixed point values. This function adds two fixed point values x and y, and returns the sum. Parameters: x  x,y: Two addends. y  x,y: Two addends. Returns: The sum. If the result runs out of range of fixed point, this function sets errno to ERANGE. See also: fixsub Definition at line 192 of file fixedmath.h.

fixed fixasin (  fixed  x  )  [inline, static]

Calculates and returns the arc sine of a fixed point. This function calculates the arc sine of the fixed point x; that is the value whose sine is x. If x falls outside the range -1 to 1, this function fails and errno is set to EDOM. Returns: Returns the arc sine in radians and the value is mathematically defined to be between -PI/2 and PI/2 (inclusive). See also: fixsin Definition at line 420 of file fixedmath.h.

fixed fixatan (  fixed  x  )

Calculates the arc tangent of a fixed point value. This function calculates the arc tangent of x; that is the value whose tangent is x. Returns: Returns the arc tangent in radians and the value is mathematically defined to be between -PI/2 and PI/2 (inclusive). See also: fixatan2

fixed fixatan2 (  fixed  y, fixed  x )

Calculates the arc tangent of two fixed point variables. This function calculates the arc tangent of the two variables x and y. It is similar to calculating the arc tangent of y / x, except that the signs of both arguments are used to determine the quadrant of the result. Returns: Returns the result in radians, which is between -PI and PI (inclusive). See also: fixatan

int fixceil (  fixed  x  )  [inline, static]

Rounds a fixed point value to the nearest integer. This function rounds the fixed point value x to the nearest integer and returns it. Returns: The rounded integer value. Definition at line 302 of file fixedmath.h.

fixed fixcos (  fixed  x  )  [inline, static]

Returns the cosine of a fixed point. This function returns the cosine of the fixed point x, where x is given in radians. See also: fixacos Definition at line 351 of file fixedmath.h.

fixed fixdiv (  fixed  x, fixed  y )  [inline, static]

Returns the quotient of two fixed point values. This function returns the quotient of two fixed point values x and y. Parameters: x  The dividend. y  The divisor. Returns: The quotient. If the result runs out of range of fixed point, this function sets errno to ERANGE. See also: fixmul Definition at line 282 of file fixedmath.h. References fixtof(), and ftofix().

fixed fixhypot (  fixed  x, fixed  y )

Returns the Euclidean distance from the origin. The function returns the sqrt(x*x+y*y). This is the length of the hypotenuse of a right-angle triangle with sides of length x and y, or the distance of the point (x,y) from the origin. See also: fixsqrt

fixed fixmul (  fixed  x, fixed  y )  [inline, static]

Returns the product of two fixed point values. This function returns the product of two fixed point values x and y. Parameters: x  The faciend. y  The multiplicato. Returns: The prodcut. If the result runs out of range of fixed point, this function sets errno to ERANGE. See also: fixdiv Definition at line 264 of file fixedmath.h. References fixtof(), and ftofix().

fixed fixsin (  fixed  x  )  [inline, static]

Returns the sine of a fixed point. This function returns the sine of the fixed point x, where x is given in radians. See also: fixasin Definition at line 365 of file fixedmath.h.

fixed fixsqrt (  fixed  x  )

Returns the non-negative square root of a fixed point value. This function returns the non-negative square root of x. It fails and sets errno to EDOM, if x is negative. See also: fixhypot

fixed fixsub (  fixed  x, fixed  y )  [inline, static]

Subtract a fixed point value from another. This function subtracts the fixed point values y from the fixed point value x, and returns the difference. Parameters: x  The minuend. y  The subtrahend. Returns: The difference. If the result runs out of range of fixed point, this function sets errno to ERANGE. See also: fixadd Definition at line 229 of file fixedmath.h.

fixed fixtan (  fixed  x  )  [inline, static]

Returns the tangent of a fixed point. This function returns the tangent of the fixed point x, where x is given in radians. See also: fixcos, fixsin Definition at line 379 of file fixedmath.h.

double fixtof (  fixed  x  )  [inline, static]

Converts a fixed point value to a float point value. This function converts the specified fixed point value x to a float point value. See also: ftofix Definition at line 172 of file fixedmath.h. Referenced by fixdiv(), and fixmul().

int fixtoi (  fixed  x  )  [inline, static]

Converts an fixed point value to an integer. This function converts the fixed point x to an integer. See also: itofix Definition at line 337 of file fixedmath.h.

fixed ftofix (  double  x  )  [inline, static]

Converts a float point value to a fixed point value. This function converts the specified float point value x to a fixed point value. Note: The float point should be ranged from -32767.0 to 32767.0. If it runs out of the range, this function sets errno to ERANGE. See also: fixtof Definition at line 148 of file fixedmath.h. Referenced by fixdiv(), and fixmul().

fixed itofix (  int  x  )  [inline, static]

Converts an integer to a fixed point value. This function converts the integer x to a fixed point value. See also: fixtoi Definition at line 324 of file fixedmath.h.

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