fix16.h

#ifndef __libfixmath_fix16_h__
#define __libfixmath_fix16_h__

#ifdef __cplusplus
extern "C"
{
#endif

/* These options may let the optimizer to remove some calls to the functions.
 * Refer to http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
 */
#ifndef FIXMATH_FUNC_ATTRS
# ifdef __GNUC__
  //#   define FIXMATH_FUNC_ATTRS __attribute__((leaf, nothrow, pure))
#   define FIXMATH_FUNC_ATTRS __attribute__((nothrow, pure))
# else
#   define FIXMATH_FUNC_ATTRS
# endif
#endif

#include <stdint.h>

typedef int32_t fix16_t;

static const fix16_t FOUR_DIV_PI  = 0x145F3;            /*!< Fix16 value of 4/PI */
static const fix16_t _FOUR_DIV_PI2 = 0xFFFF9840;        /*!< Fix16 value of -4/PI² */
static const fix16_t X4_CORRECTION_COMPONENT = 0x399A; 	/*!< Fix16 value of 0.225 */
static const fix16_t PI_DIV_4 = 0x0000C90F;             /*!< Fix16 value of PI/4 */
static const fix16_t THREE_PI_DIV_4 = 0x00025B2F;       /*!< Fix16 value of 3PI/4 */

static const fix16_t fix16_max = 0x7FFFFFFF; /*!< the maximum value of fix16_t */
static const fix16_t fix16_min = 0x80000000; /*!< the minimum value of fix16_t */
static const fix16_t fix16_overflow = 0x80000000; /*!< the value used to indicate overflows when FIXMATH_NO_OVERFLOW is not specified */

static const fix16_t fix16_pi  = 205887;     /*!< fix16_t value of pi */
static const fix16_t fix16_e   = 178145;     /*!< fix16_t value of e */
static const fix16_t fix16_one = 0x00010000; /*!< fix16_t value of 1 */
static const fix16_t fix16_two = 0x00020000; /*!< fix16_t value of 2 */

/* Conversion functions between fix16_t and float/integer.
 * These are inlined to allow compiler to optimize away constant numbers
 */
static inline fix16_t fix16_from_int(int a) { return a * fix16_one; }
static inline float fix16_to_float(fix16_t a) { return (float)a / fix16_one; }
static inline double fix16_to_dbl(fix16_t a) { return (double)a / fix16_one; }

static inline int fix16_to_int(fix16_t a)
{
#ifdef FIXMATH_NO_ROUNDING
    return a >> 16;
#else
    if (a >= 0)
        return (a + fix16_one / 2) / fix16_one;
    else
        return (a - fix16_one / 2) / fix16_one;
#endif
}

static inline fix16_t fix16_from_float(float a)
{
    float temp = a * fix16_one;
#ifndef FIXMATH_NO_ROUNDING
    temp += (temp >= 0) ? 0.5f : -0.5f;
#endif
    return (fix16_t)temp;
}

static inline fix16_t fix16_from_dbl(double a)
{
    double temp = a * fix16_one;
#ifndef FIXMATH_NO_ROUNDING
    temp += (temp >= 0) ? 0.5f : -0.5f;
#endif
    return (fix16_t)temp;
}

/* Subtraction and addition with (optional) overflow detection. */
#ifdef FIXMATH_NO_OVERFLOW

static inline fix16_t fix16_add(fix16_t inArg0, fix16_t inArg1) { return (inArg0 + inArg1); }
static inline fix16_t fix16_sub(fix16_t inArg0, fix16_t inArg1) { return (inArg0 - inArg1); }

#else

extern fix16_t fix16_add(fix16_t a, fix16_t b) FIXMATH_FUNC_ATTRS;
extern fix16_t fix16_sub(fix16_t a, fix16_t b) FIXMATH_FUNC_ATTRS;

/* Saturating arithmetic */
extern fix16_t fix16_sadd(fix16_t a, fix16_t b) FIXMATH_FUNC_ATTRS;
extern fix16_t fix16_ssub(fix16_t a, fix16_t b) FIXMATH_FUNC_ATTRS;

#endif

/*! Multiplies the two given fix16_t's and returns the result.
*/
extern fix16_t fix16_mul(fix16_t inArg0, fix16_t inArg1) FIXMATH_FUNC_ATTRS;

/*! Divides the first given fix16_t by the second and returns the result.
*/
extern fix16_t fix16_div(fix16_t inArg0, fix16_t inArg1) FIXMATH_FUNC_ATTRS;

#ifndef FIXMATH_NO_OVERFLOW
/*! Performs a saturated multiplication (overflow-protected) of the two given fix16_t's and returns the result.
*/
extern fix16_t fix16_smul(fix16_t inArg0, fix16_t inArg1) FIXMATH_FUNC_ATTRS;

/*! Performs a saturated division (overflow-protected) of the first fix16_t by the second and returns the result.
*/
extern fix16_t fix16_sdiv(fix16_t inArg0, fix16_t inArg1) FIXMATH_FUNC_ATTRS;
#endif

/*! Returns the linear interpolation: (inArg0 * (1 - inFract)) + (inArg1 * inFract)
*/
extern fix16_t fix16_lerp8(fix16_t inArg0, fix16_t inArg1, uint8_t inFract) FIXMATH_FUNC_ATTRS;
extern fix16_t fix16_lerp16(fix16_t inArg0, fix16_t inArg1, uint16_t inFract) FIXMATH_FUNC_ATTRS;
#ifndef FIXMATH_NO_64BIT
extern fix16_t fix16_lerp32(fix16_t inArg0, fix16_t inArg1, uint32_t inFract) FIXMATH_FUNC_ATTRS;
#endif

/*! Returns the sine of the given fix16_t.
*/
extern fix16_t fix16_sin_parabola(fix16_t inAngle) FIXMATH_FUNC_ATTRS;

/*! Returns the sine of the given fix16_t.
*/
extern fix16_t fix16_sin(fix16_t inAngle) FIXMATH_FUNC_ATTRS;

/*! Returns the cosine of the given fix16_t.
*/
extern fix16_t fix16_cos(fix16_t inAngle) FIXMATH_FUNC_ATTRS;

/*! Returns the tangent of the given fix16_t.
*/
extern fix16_t fix16_tan(fix16_t inAngle) FIXMATH_FUNC_ATTRS;

/*! Returns the arcsine of the given fix16_t.
*/
extern fix16_t fix16_asin(fix16_t inValue) FIXMATH_FUNC_ATTRS;

/*! Returns the arccosine of the given fix16_t.
*/
extern fix16_t fix16_acos(fix16_t inValue) FIXMATH_FUNC_ATTRS;

/*! Returns the arctangent of the given fix16_t.
*/
extern fix16_t fix16_atan(fix16_t inValue) FIXMATH_FUNC_ATTRS;

/*! Returns the arctangent of inY/inX.
*/
extern fix16_t fix16_atan2(fix16_t inY, fix16_t inX) FIXMATH_FUNC_ATTRS;



/*! Returns the square root of the given fix16_t.
*/
extern fix16_t fix16_sqrt(fix16_t inValue) FIXMATH_FUNC_ATTRS;



/*! Returns the exponent (e^) of the given fix16_t.
*/
extern fix16_t fix16_exp(fix16_t inValue) FIXMATH_FUNC_ATTRS;

#ifdef __cplusplus
}
#include "fix16.hpp"
#endif

#endif