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/*

 * Copyright 2009 Red Hat Inc.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sublicense,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR

 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,

 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR

 * OTHER DEALINGS IN THE SOFTWARE.

 *

 * Authors: Dave Airlie

 *          Christian König

 */

#ifndef DRM_FIXED_H

#define DRM_FIXED_H

#include 

typedef union dfixed {

	u32 full;

} fixed20_12;

#define dfixed_const(A) (u32)(((A) << 12))/*  + ((B + 0.000122)*4096)) */

#define dfixed_const_half(A) (u32)(((A) << 12) + 2048)

#define dfixed_const_666(A) (u32)(((A) << 12) + 2731)

#define dfixed_const_8(A) (u32)(((A) << 12) + 3277)

#define dfixed_mul(A, B) ((u64)((u64)(A).full * (B).full + 2048) >> 12)

#define dfixed_init(A) { .full = dfixed_const((A)) }

#define dfixed_init_half(A) { .full = dfixed_const_half((A)) }

#define dfixed_trunc(A) ((A).full >> 12)

#define dfixed_frac(A) ((A).full & ((1 << 12) - 1))

static inline u32 dfixed_floor(fixed20_12 A)

{

	u32 non_frac = dfixed_trunc(A);

	return dfixed_const(non_frac);

}

static inline u32 dfixed_ceil(fixed20_12 A)

{

	u32 non_frac = dfixed_trunc(A);

	if (A.full > dfixed_const(non_frac))

		return dfixed_const(non_frac + 1);

	else

		return dfixed_const(non_frac);

}

static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B)

{

	u64 tmp = ((u64)A.full << 13);

	do_div(tmp, B.full);

	tmp += 1;

	tmp /= 2;

	return lower_32_bits(tmp);

}

#define DRM_FIXED_POINT		32

#define DRM_FIXED_ONE		(1ULL << DRM_FIXED_POINT)

#define DRM_FIXED_DECIMAL_MASK	(DRM_FIXED_ONE - 1)

#define DRM_FIXED_DIGITS_MASK	(~DRM_FIXED_DECIMAL_MASK)

#define DRM_FIXED_EPSILON	1LL

#define DRM_FIXED_ALMOST_ONE	(DRM_FIXED_ONE - DRM_FIXED_EPSILON)

static inline s64 drm_int2fixp(int a)

{

	return ((s64)a) << DRM_FIXED_POINT;

}

static inline int drm_fixp2int(s64 a)

{

	return ((s64)a) >> DRM_FIXED_POINT;

}

static inline int drm_fixp2int_ceil(s64 a)

{

	if (a > 0)

		return drm_fixp2int(a + DRM_FIXED_ALMOST_ONE);

	else

		return drm_fixp2int(a - DRM_FIXED_ALMOST_ONE);

}

static inline unsigned drm_fixp_msbset(s64 a)

{

	unsigned shift, sign = (a >> 63) & 1;

	for (shift = 62; shift > 0; --shift)

		if (((a >> shift) & 1) != sign)

			return shift;

	return 0;

}

static inline s64 drm_fixp_mul(s64 a, s64 b)

{

	unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b);

	s64 result;

	if (shift > 61) {

		shift = shift - 61;

		a >>= (shift >> 1) + (shift & 1);

		b >>= shift >> 1;

	} else

		shift = 0;

	result = a * b;

	if (shift > DRM_FIXED_POINT)

		return result << (shift - DRM_FIXED_POINT);

	if (shift < DRM_FIXED_POINT)

		return result >> (DRM_FIXED_POINT - shift);

	return result;

}

static inline s64 drm_fixp_div(s64 a, s64 b)

{

	unsigned shift = 62 - drm_fixp_msbset(a);

	s64 result;

	a <<= shift;

	if (shift < DRM_FIXED_POINT)

		b >>= (DRM_FIXED_POINT - shift);

	result = div64_s64(a, b);

	if (shift > DRM_FIXED_POINT)

		return result >> (shift - DRM_FIXED_POINT);

	return result;

}

static inline s64 drm_fixp_from_fraction(s64 a, s64 b)

{

	s64 res;

	bool a_neg = a < 0;

	bool b_neg = b < 0;

	u64 a_abs = a_neg ? -a : a;

	u64 b_abs = b_neg ? -b : b;

	u64 rem;

	/* determine integer part */

	u64 res_abs  = div64_u64_rem(a_abs, b_abs, &rem);

	/* determine fractional part */

	{

		u32 i = DRM_FIXED_POINT;

		do {

			rem <<= 1;

			res_abs <<= 1;

			if (rem >= b_abs) {

				res_abs |= 1;

				rem -= b_abs;

			}

		} while (--i != 0);

	}

	/* round up LSB */

	{

		u64 summand = (rem << 1) >= b_abs;

		res_abs += summand;

	}

	res = (s64) res_abs;

	if (a_neg ^ b_neg)

		res = -res;

	return res;

}

static inline s64 drm_fixp_exp(s64 x)

{

	s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000);

	s64 sum = DRM_FIXED_ONE, term, y = x;

	u64 count = 1;

	if (x < 0)

		y = -1 * x;

	term = y;

	while (term >= tolerance) {

		sum = sum + term;

		count = count + 1;

		term = drm_fixp_mul(term, div64_s64(y, count));

	}

	if (x < 0)

		sum = drm_fixp_div(DRM_FIXED_ONE, sum);

	return sum;

}

#endif