/*---------------------------------------------------------------------------*
  Project:  TwlSDK - FX - 
  File:     fx_atanidx.c

  Copyright 2003-2008 Nintendo.  All rights reserved.

  These coded instructions, statements, and computer programs contain
  proprietary information of Nintendo of America Inc. and/or Nintendo
  Company Ltd., and are protected by Federal copyright law.  They may
  not be disclosed to third parties or copied or duplicated in any form,
  in whole or in part, without the prior written consent of Nintendo.

  $Date:: 2008-09-18#$
  $Rev: 8573 $
  $Author: okubata_ryoma $

 *---------------------------------------------------------------------------*/

#include <nitro/fx/fx_trig.h>
#include <nitro/fx/fx_cp.h>
#include <nitro/fx/fx_const.h>

const fx16 FX_AtanIdxTable_[128 + 1] = {
    (u16)0,
    (u16)81,
    (u16)163,
    (u16)244,
    (u16)326,
    (u16)407,
    (u16)489,
    (u16)570,
    (u16)651,
    (u16)732,
    (u16)813,
    (u16)894,
    (u16)975,
    (u16)1056,
    (u16)1136,
    (u16)1217,
    (u16)1297,
    (u16)1377,
    (u16)1457,
    (u16)1537,
    (u16)1617,
    (u16)1696,
    (u16)1775,
    (u16)1854,
    (u16)1933,
    (u16)2012,
    (u16)2090,
    (u16)2168,
    (u16)2246,
    (u16)2324,
    (u16)2401,
    (u16)2478,
    (u16)2555,
    (u16)2632,
    (u16)2708,
    (u16)2784,
    (u16)2860,
    (u16)2935,
    (u16)3010,
    (u16)3085,
    (u16)3159,
    (u16)3233,
    (u16)3307,
    (u16)3380,
    (u16)3453,
    (u16)3526,
    (u16)3599,
    (u16)3670,
    (u16)3742,
    (u16)3813,
    (u16)3884,
    (u16)3955,
    (u16)4025,
    (u16)4095,
    (u16)4164,
    (u16)4233,
    (u16)4302,
    (u16)4370,
    (u16)4438,
    (u16)4505,
    (u16)4572,
    (u16)4639,
    (u16)4705,
    (u16)4771,
    (u16)4836,
    (u16)4901,
    (u16)4966,
    (u16)5030,
    (u16)5094,
    (u16)5157,
    (u16)5220,
    (u16)5282,
    (u16)5344,
    (u16)5406,
    (u16)5467,
    (u16)5528,
    (u16)5589,
    (u16)5649,
    (u16)5708,
    (u16)5768,
    (u16)5826,
    (u16)5885,
    (u16)5943,
    (u16)6000,
    (u16)6058,
    (u16)6114,
    (u16)6171,
    (u16)6227,
    (u16)6282,
    (u16)6337,
    (u16)6392,
    (u16)6446,
    (u16)6500,
    (u16)6554,
    (u16)6607,
    (u16)6660,
    (u16)6712,
    (u16)6764,
    (u16)6815,
    (u16)6867,
    (u16)6917,
    (u16)6968,
    (u16)7018,
    (u16)7068,
    (u16)7117,
    (u16)7166,
    (u16)7214,
    (u16)7262,
    (u16)7310,
    (u16)7358,
    (u16)7405,
    (u16)7451,
    (u16)7498,
    (u16)7544,
    (u16)7589,
    (u16)7635,
    (u16)7679,
    (u16)7724,
    (u16)7768,
    (u16)7812,
    (u16)7856,
    (u16)7899,
    (u16)7942,
    (u16)7984,
    (u16)8026,
    (u16)8068,
    (u16)8110,
    (u16)8151,
    (u16)8192
};


/*---------------------------------------------------------------------------*
  Name:         FX_AtanIdx

  Description:  Computes an arc tangent of the input value, making use of
                a table.

  Arguments:    x            Y/X in fx32 format

  Returns:      result in u16 format (0 - 65535)
 *---------------------------------------------------------------------------*/
u16 FX_AtanIdx(fx32 x)
{
    if (x >= 0)
    {
        if (x > FX32_ONE)
        {
            return (u16)(16384 - FX_AtanIdxTable_[FX_Inv(x) >> 5]);
        }
        else if (x < FX32_ONE)
        {
            return (u16)FX_AtanIdxTable_[x >> 5];
        }
        else
        {
            return (u16)8192;
        }
    }
    else
    {
        if (x < -FX32_ONE)
        {
            return (u16)(-16384 + FX_AtanIdxTable_[FX_Inv(-x) >> 5]);
        }
        else if (x > -FX32_ONE)
        {
            return (u16)-FX_AtanIdxTable_[-x >> 5];
        }
        else
        {
            return (u16)-8192;
        }
    }
}


/*---------------------------------------------------------------------------*
  Name:         FX_Atan2Idx

  Description:  Computes an arc tangent of the input value(y/x), making use of
                a table. Note that 'y' is the first argument.

  Arguments:    y            a value in fx32 format
                x            a value in fx32 format
  
  Returns:      result in u16 format (0 - 65535)
 *---------------------------------------------------------------------------*/
u16 FX_Atan2Idx(fx32 y, fx32 x)
{
    fx32    a, b;
    int     c;
    int     sgn;

    if (y > 0)
    {
        if (x > 0)
        {
            if (x > y)
            {
                a = y;
                b = x;
                c = 0;
                sgn = 1;
            }
            else if (x < y)
            {
                a = x;
                b = y;
                c = 16384;
                sgn = 0;
            }
            else
            {
                return (u16)8192;
            }
        }
        else if (x < 0)
        {
            x = -x;
            if (x < y)
            {
                a = x;
                b = y;
                c = 16384;
                sgn = 1;
            }
            else if (x > y)
            {
                a = y;
                b = x;
                c = 32768;
                sgn = 0;
            }
            else
            {
                return (u16)24576;
            }
        }
        else
        {
            return (u16)16384;
        }
    }
    else if (y < 0)
    {
        y = -y;
        if (x < 0)
        {
            x = -x;
            if (x > y)
            {
                a = y;
                b = x;
                c = -32768;
                sgn = 1;
            }
            else if (x < y)
            {
                a = x;
                b = y;
                c = -16384;
                sgn = 0;
            }
            else
            {
                return (u16)-24576;
            }
        }
        else if (x > 0)
        {
            if (x < y)
            {
                a = x;
                b = y;
                c = -16384;
                sgn = 1;
            }
            else if (x > y)
            {
                a = y;
                b = x;
                c = 0;
                sgn = 0;
            }
            else
            {
                return (u16)-8192;
            }
        }
        else
        {
            return (u16)-16384;
        }
    }
    else                               // y = 0
    {
        if (x >= 0)
        {
            return 0;
        }
        else
        {
            return (u16)32768;
        }
    }

    if (b == 0)
        return 0;
    if (sgn)
        return (u16)(c + FX_AtanIdxTable_[FX_Div(a, b) >> 5]);
    else
        return (u16)(c - FX_AtanIdxTable_[FX_Div(a, b) >> 5]);
}