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>
#include <linux/types.h>
#include <linux/wordpart.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_sm2fixp(__u64 a)
{
    if ((a & (1LL << 63))) {
        return -(a & 0x7fffffffffffffffll);
    } else {
        return a;
    }
}
 
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_round(s64 a)
{
    return drm_fixp2int(a + DRM_FIXED_ONE / 2);
}
 
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;
}
 
static inline int fxp_q4_from_int(int val_int)
{
    return val_int << 4;
}
 
static inline int fxp_q4_to_int(int val_q4)
{
    return val_q4 >> 4;
}
 
static inline int fxp_q4_to_int_roundup(int val_q4)
{
    return (val_q4 + 0xf) >> 4;
}
 
static inline int fxp_q4_to_frac(int val_q4)
{
    return val_q4 & 0xf;
}
 
#define FXP_Q4_FMT      "%d.%04d"
#define FXP_Q4_ARGS(val_q4) fxp_q4_to_int(val_q4), (fxp_q4_to_frac(val_q4) * 625)
 
#endif