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sys/dev/drm/core/include/drm/drm_fixed.h
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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 <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) | |||||
#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 |