#include "FixedMath.h"

#include <math.h>

namespace FixedMath
{

static const double Pi = 3.1415926535897932384626433832795;

MathTable::TableData MathTable::Table;

MathTable::TableData::TableData(void)
{
	int i;
	for (i = 0;i < AngleNum;i++)
	{
		SinTable[i] = static_cast<short>(Fixed(
						sin(Pi * i / (AngleNum / 2))
						).GetFixedValue());
	}

	for (i = 0;i < 1 << (2 + SqrtBelowPointPrecision);i++)
	{
		SqrtTable[i] = static_cast<short>(Fixed(
						sqrt(static_cast<double>(i) / (1 << SqrtBelowPointPrecision))
						).GetFixedValue());
	}

	double a45 = (1 << AtanTableBit);
	for (i = 0;i < (1 << AtanTableBit) + 1;i++)
	{
		AtanTable[i] = static_cast<short>(atan(i / a45) * AngleNum / 2 / Pi);
	}

}

Fixed Sqrt(Fixed square)
{
	int i = 0;
	long sq = square.GetFixedValue();

	while (sq >= Fixed(256).GetFixedValue())
	{
		i += 4;sq >>= 8;
	}
	if (sq >= Fixed(64).GetFixedValue())
	{
		i += 3;sq >>= 6;
	}
	if (sq >= Fixed(16).GetFixedValue())
	{
		i += 2;sq >>= 4;
	}
	if (sq >= Fixed(4).GetFixedValue())
	{
		i++;sq >>= 2;
	}
	return Fixed::FixedValue(
		MathTable::Table.SqrtTable[sq >> (FixedShift - SqrtBelowPointPrecision)] << i
		);
}

short Atan(long x,long y)
{
	if (x == 0 && y == 0)
		return 0;
	long max = 1 << (31 - AtanTableBit);
	if (x >= max || x < -max || y >= max || y < -max)
	{	//途中でオーバーフローしそうなら
		x >>= AtanTableBit;
		y >>= AtanTableBit;
	}

	if (y >= 0)
		if (x >= 0)
		{
			if (x > y)
				return MathTable::Table.AtanTable[(y << AtanTableBit) / x];
			else
				return (AngleNum >> 2) - MathTable::Table.AtanTable[(x << AtanTableBit) / y];
		}
		else
		{
			if (y > -x)
				return (AngleNum >> 2) + MathTable::Table.AtanTable[(-x << AtanTableBit) / y];
			else
				return (AngleNum >> 1) - MathTable::Table.AtanTable[(y << AtanTableBit) / -x];
		}
	else
	{
		if (x <= 0)
		{
			if (-x > -y)
				return (AngleNum >> 1) + MathTable::Table.AtanTable[(-y << AtanTableBit) / -x];
			else
				return AngleNum - (AngleNum >> 2) - MathTable::Table.AtanTable[(-x << AtanTableBit) / -y];
		}
		else
		{
			if (-y > x)
				return AngleNum - (AngleNum >> 2) + MathTable::Table.AtanTable[(x << AtanTableBit) / -y];
			else
				return AngleNum - MathTable::Table.AtanTable[(-y << AtanTableBit) / x];
		}
	}
}

}