fixed.h

/*---------------------------------------------------------------------------------
 
    snestypes.h -- fixed points (and a few useful macros)
 
    Copyright (C) 2025
        Alekmaul
 
    This software is provided 'as-is', without any express or implied
    warranty.  In no event will the authors be held liable for any
    damages arising from the use of this software.
 
    Permission is granted to anyone to use this software for any
    purpose, including commercial applications, and to alter it and
    redistribute it freely, subject to the following restrictions:
 
    1.  The origin of this software must not be misrepresented; you
        must not claim that you wrote the original software. If you use
        this software in a product, an acknowledgment in the product
        documentation would be appreciated but is not required.
    2.  Altered source versions must be plainly marked as such, and
        must not be misrepresented as being the original software.
    3.  This notice may not be removed or altered from any source
        distribution.
 
    fixed point definition inspired by SGDK from Stephane Dallongeville
        https://github.com/Stephane-D/SGDK/blob/master/inc/maths.h
---------------------------------------------------------------------------------*/
#include <snes/snestypes.h>
 
typedef s16 fx16;
 
#define FX16_INT_BITS              10
#define FX16_FRAC_BITS             (16 - FX16_INT_BITS)
#define FX16_INT_MASK              (((1 << FX16_INT_BITS) - 1) << FX16_FRAC_BITS)
#define FX16_FRAC_MASK             ((1 << FX16_FRAC_BITS) - 1)
 
#define FX16(value)                ((FX16) ((value) * (1 << FX16_FRAC_BITS)))
 
#define ifromfx16(value)           ((value) >> FX16_FRAC_BITS)
 
#define dfromfx16(value)           ((value) << FX16_FRAC_BITS)
 
#define fx16mul(val1, val2)   ((val1 * val2) >> FX16_FRAC_BITS)
 
#define fx16div(val1, val2)   (((val1 << FX16_FRAC_BITS) / val2);