/*
* 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 <linux/math64.h>

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)

static inline s64 drm_int2fixp(int a)
{
return ((s64)a) << DRM_FIXED_POINT;
}

static inline int drm_fixp2int(int64_t a)
{
return ((s64)a) >> DRM_FIXED_POINT;
}

static inline unsigned drm_fixp_msbset(int64_t 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_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