/*
 *  M_APM  -  mapm_add.c
 *
 *  Copyright (C) 1999 - 2007   Michael C. Ring
 *
 *  Permission to use, copy, and distribute this software and its
 *  documentation for any purpose with or without fee is hereby granted,
 *  provided that the above copyright notice appear in all copies and
 *  that both that copyright notice and this permission notice appear
 *  in supporting documentation.
 *
 *  Permission to modify the software is granted. Permission to distribute
 *  the modified code is granted. Modifications are to be distributed by
 *  using the file 'license.txt' as a template to modify the file header.
 *  'license.txt' is available in the official MAPM distribution.
 *
 *  This software is provided "as is" without express or implied warranty.
 */

/*
 *
 *      This file contains the functions that implement the sin (5x)
 *	and cos (4x) multiple angle relations
 *
 */

#include "pgAdmin3.h"
#include "pgscript/utilities/mapm-lib/m_apm_lc.h"

static	M_APM	M_work1 = NULL;
static	M_APM	M_work2 = NULL;
static	int	M_add_firsttime = TRUE;

/****************************************************************************/
void	M_free_all_add()
{
	if (M_add_firsttime == FALSE)
	{
		m_apm_free(M_work1);
		m_apm_free(M_work2);
		M_add_firsttime = TRUE;
	}
}
/****************************************************************************/
void	m_apm_add(M_APM r, M_APM a, M_APM b)
{
	int	j, carry, sign, aexp, bexp, adigits, bdigits;

	if (M_add_firsttime)
	{
		M_add_firsttime = FALSE;
		M_work1 = m_apm_init();
		M_work2 = m_apm_init();
	}

	if (a->m_apm_sign == 0)
	{
		m_apm_copy(r, b);
		return;
	}

	if (b->m_apm_sign == 0)
	{
		m_apm_copy(r, a);
		return;
	}

	if (a->m_apm_sign == 1 && b->m_apm_sign == -1)
	{
		b->m_apm_sign = 1;
		m_apm_subtract(r, a, b);
		b->m_apm_sign = -1;
		return;
	}

	if (a->m_apm_sign == -1 && b->m_apm_sign == 1)
	{
		a->m_apm_sign = 1;
		m_apm_subtract(r, b, a);
		a->m_apm_sign = -1;
		return;
	}

	sign = a->m_apm_sign;         /* signs are the same, result will be same */

	aexp = a->m_apm_exponent;
	bexp = b->m_apm_exponent;

	m_apm_copy(M_work1, a);
	m_apm_copy(M_work2, b);

	/*
	 *  scale by at least 1 factor of 10 in case the MSB carrys
	 */

	if (aexp == bexp)
	{
		M_apm_scale(M_work1, 2);   /* shift 2 digits == 1 byte for efficiency */
		M_apm_scale(M_work2, 2);
	}
	else
	{
		if (aexp > bexp)
		{
			M_apm_scale(M_work1, 2);
			M_apm_scale(M_work2, (aexp + 2 - bexp));
		}
		else            /*  aexp < bexp  */
		{
			M_apm_scale(M_work2, 2);
			M_apm_scale(M_work1, (bexp + 2 - aexp));
		}
	}

	adigits = M_work1->m_apm_datalength;
	bdigits = M_work2->m_apm_datalength;

	if (adigits >= bdigits)
	{
		m_apm_copy(r, M_work1);
		j = (bdigits + 1) >> 1;
		carry = 0;

		while (TRUE)
		{
			j--;
			r->m_apm_data[j] += carry + M_work2->m_apm_data[j];

			if (r->m_apm_data[j] >= 100)
			{
				r->m_apm_data[j] -= 100;
				carry = 1;
			}
			else
				carry = 0;

			if (j == 0)
				break;
		}
	}
	else
	{
		m_apm_copy(r, M_work2);
		j = (adigits + 1) >> 1;
		carry = 0;

		while (TRUE)
		{
			j--;
			r->m_apm_data[j] += carry + M_work1->m_apm_data[j];

			if (r->m_apm_data[j] >= 100)
			{
				r->m_apm_data[j] -= 100;
				carry = 1;
			}
			else
				carry = 0;

			if (j == 0)
				break;
		}
	}

	r->m_apm_sign = sign;

	M_apm_normalize(r);
}
/****************************************************************************/
void	m_apm_subtract(M_APM r, M_APM a, M_APM b)
{
	int	itmp, j, flag, icompare, sign, aexp, bexp,
	    borrow, adigits, bdigits;

	if (M_add_firsttime)
	{
		M_add_firsttime = FALSE;
		M_work1 = m_apm_init();
		M_work2 = m_apm_init();
	}

	if (b->m_apm_sign == 0)
	{
		m_apm_copy(r, a);
		return;
	}

	if (a->m_apm_sign == 0)
	{
		m_apm_copy(r, b);
		r->m_apm_sign = -(r->m_apm_sign);
		return;
	}

	if (a->m_apm_sign == 1 && b->m_apm_sign == -1)
	{
		b->m_apm_sign = 1;
		m_apm_add(r, a, b);
		b->m_apm_sign = -1;
		return;
	}

	if (a->m_apm_sign == -1 && b->m_apm_sign == 1)
	{
		b->m_apm_sign = -1;
		m_apm_add(r, a, b);
		b->m_apm_sign = 1;
		return;
	}

	/* now, the signs are the same  */
	/* make a positive working copy */

	m_apm_absolute_value(M_work1, a);
	m_apm_absolute_value(M_work2, b);

	/* are they the same??  if so, the result is zero */

	if ((icompare = m_apm_compare(M_work1, M_work2)) == 0)
	{
		M_set_to_zero(r);
		return;
	}

	if (icompare == 1)             /*  |a| > |b|  (do A-B)  */
	{
		flag = TRUE;
		sign = a->m_apm_sign;
	}
	else                           /*  |b| > |a|  (do B-A)  */
	{
		flag = FALSE;
		sign = -(a->m_apm_sign);
	}

	aexp = M_work1->m_apm_exponent;
	bexp = M_work2->m_apm_exponent;

	if (aexp > bexp)
		M_apm_scale(M_work2, (aexp - bexp));

	if (aexp < bexp)
		M_apm_scale(M_work1, (bexp - aexp));

	adigits = M_work1->m_apm_datalength;
	bdigits = M_work2->m_apm_datalength;

	if (adigits > bdigits)
		M_apm_pad(M_work2, adigits);

	if (adigits < bdigits)
		M_apm_pad(M_work1, bdigits);

	if (flag)		/* perform A-B,  M_work1 - M_work2 */
	{
		m_apm_copy(r, M_work1);
		j = (r->m_apm_datalength + 1) >> 1;
		borrow = 0;

		while (TRUE)
		{
			j--;
			itmp = (int)r->m_apm_data[j] - ((int)M_work2->m_apm_data[j] + borrow);

			if (itmp >= 0)
			{
				r->m_apm_data[j] = (UCHAR)itmp;
				borrow = 0;
			}
			else
			{
				r->m_apm_data[j] = (UCHAR)(100 + itmp);
				borrow = 1;
			}

			if (j == 0)
				break;
		}
	}
	else   		/* perform B-A,  M_work2 - M_work1 */
	{
		m_apm_copy(r, M_work2);
		j = (r->m_apm_datalength + 1) >> 1;
		borrow = 0;

		while (TRUE)
		{
			j--;
			itmp = (int)r->m_apm_data[j] - ((int)M_work1->m_apm_data[j] + borrow);

			if (itmp >= 0)
			{
				r->m_apm_data[j] = (UCHAR)itmp;
				borrow = 0;
			}
			else
			{
				r->m_apm_data[j] = (UCHAR)(100 + itmp);
				borrow = 1;
			}

			if (j == 0)
				break;
		}
	}

	r->m_apm_sign = sign;

	M_apm_normalize(r);
}
/****************************************************************************/

#ifdef __cplusplus

MAPM operator+(const MAPM &a, const MAPM &b)
{
	MAPM ret;
	m_apm_add(ret.val(), a.cval(), b.cval());
	return ret;
}
MAPM operator-(const MAPM &a, const MAPM &b)
{
	MAPM ret;
	m_apm_subtract(ret.val(), a.cval(), b.cval());
	return ret;
}

#endif