Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0-or-later */
       2             : #ifndef _FIXP_ARITH_H
       3             : #define _FIXP_ARITH_H
       4             : 
       5             : #include <linux/math64.h>
       6             : 
       7             : /*
       8             :  * Simplistic fixed-point arithmetics.
       9             :  * Hmm, I'm probably duplicating some code :(
      10             :  *
      11             :  * Copyright (c) 2002 Johann Deneux
      12             :  */
      13             : 
      14             : /*
      15             :  *
      16             :  * Should you need to contact me, the author, you can do so by
      17             :  * e-mail - mail your message to <johann.deneux@gmail.com>
      18             :  */
      19             : 
      20             : #include <linux/types.h>
      21             : 
      22             : static const s32 sin_table[] = {
      23             :         0x00000000, 0x023be165, 0x04779632, 0x06b2f1d2, 0x08edc7b6, 0x0b27eb5c,
      24             :         0x0d61304d, 0x0f996a26, 0x11d06c96, 0x14060b67, 0x163a1a7d, 0x186c6ddd,
      25             :         0x1a9cd9ac, 0x1ccb3236, 0x1ef74bf2, 0x2120fb82, 0x234815ba, 0x256c6f9e,
      26             :         0x278dde6e, 0x29ac379f, 0x2bc750e8, 0x2ddf003f, 0x2ff31bdd, 0x32037a44,
      27             :         0x340ff241, 0x36185aee, 0x381c8bb5, 0x3a1c5c56, 0x3c17a4e7, 0x3e0e3ddb,
      28             :         0x3fffffff, 0x41ecc483, 0x43d464fa, 0x45b6bb5d, 0x4793a20f, 0x496af3e1,
      29             :         0x4b3c8c11, 0x4d084650, 0x4ecdfec6, 0x508d9210, 0x5246dd48, 0x53f9be04,
      30             :         0x55a6125a, 0x574bb8e5, 0x58ea90c2, 0x5a827999, 0x5c135399, 0x5d9cff82,
      31             :         0x5f1f5ea0, 0x609a52d1, 0x620dbe8a, 0x637984d3, 0x64dd894f, 0x6639b039,
      32             :         0x678dde6d, 0x68d9f963, 0x6a1de735, 0x6b598ea1, 0x6c8cd70a, 0x6db7a879,
      33             :         0x6ed9eba0, 0x6ff389de, 0x71046d3c, 0x720c8074, 0x730baeec, 0x7401e4bf,
      34             :         0x74ef0ebb, 0x75d31a5f, 0x76adf5e5, 0x777f903b, 0x7847d908, 0x7906c0af,
      35             :         0x79bc384c, 0x7a6831b8, 0x7b0a9f8c, 0x7ba3751c, 0x7c32a67c, 0x7cb82884,
      36             :         0x7d33f0c8, 0x7da5f5a3, 0x7e0e2e31, 0x7e6c924f, 0x7ec11aa3, 0x7f0bc095,
      37             :         0x7f4c7e52, 0x7f834ecf, 0x7fb02dc4, 0x7fd317b3, 0x7fec09e1, 0x7ffb025e,
      38             :         0x7fffffff
      39             : };
      40             : 
      41             : /**
      42             :  * __fixp_sin32() returns the sin of an angle in degrees
      43             :  *
      44             :  * @degrees: angle, in degrees, from 0 to 360.
      45             :  *
      46             :  * The returned value ranges from -0x7fffffff to +0x7fffffff.
      47             :  */
      48             : static inline s32 __fixp_sin32(int degrees)
      49             : {
      50             :         s32 ret;
      51           0 :         bool negative = false;
      52             : 
      53           0 :         if (degrees > 180) {
      54           0 :                 negative = true;
      55           0 :                 degrees -= 180;
      56             :         }
      57           0 :         if (degrees > 90)
      58           0 :                 degrees = 180 - degrees;
      59             : 
      60           0 :         ret = sin_table[degrees];
      61             : 
      62           0 :         return negative ? -ret : ret;
      63             : }
      64             : 
      65             : /**
      66             :  * fixp_sin32() returns the sin of an angle in degrees
      67             :  *
      68             :  * @degrees: angle, in degrees. The angle can be positive or negative
      69             :  *
      70             :  * The returned value ranges from -0x7fffffff to +0x7fffffff.
      71             :  */
      72             : static inline s32 fixp_sin32(int degrees)
      73             : {
      74           0 :         degrees = (degrees % 360 + 360) % 360;
      75             : 
      76           0 :         return __fixp_sin32(degrees);
      77             : }
      78             : 
      79             : /* cos(x) = sin(x + 90 degrees) */
      80             : #define fixp_cos32(v) fixp_sin32((v) + 90)
      81             : 
      82             : /*
      83             :  * 16 bits variants
      84             :  *
      85             :  * The returned value ranges from -0x7fff to 0x7fff
      86             :  */
      87             : 
      88             : #define fixp_sin16(v) (fixp_sin32(v) >> 16)
      89             : #define fixp_cos16(v) (fixp_cos32(v) >> 16)
      90             : 
      91             : /**
      92             :  * fixp_sin32_rad() - calculates the sin of an angle in radians
      93             :  *
      94             :  * @radians: angle, in radians
      95             :  * @twopi: value to be used for 2*pi
      96             :  *
      97             :  * Provides a variant for the cases where just 360
      98             :  * values is not enough. This function uses linear
      99             :  * interpolation to a wider range of values given by
     100             :  * twopi var.
     101             :  *
     102             :  * Experimental tests gave a maximum difference of
     103             :  * 0.000038 between the value calculated by sin() and
     104             :  * the one produced by this function, when twopi is
     105             :  * equal to 360000. That seems to be enough precision
     106             :  * for practical purposes.
     107             :  *
     108             :  * Please notice that two high numbers for twopi could cause
     109             :  * overflows, so the routine will not allow values of twopi
     110             :  * bigger than 1^18.
     111             :  */
     112             : static inline s32 fixp_sin32_rad(u32 radians, u32 twopi)
     113             : {
     114             :         int degrees;
     115             :         s32 v1, v2, dx, dy;
     116             :         s64 tmp;
     117             : 
     118             :         /*
     119             :          * Avoid too large values for twopi, as we don't want overflows.
     120             :          */
     121             :         BUG_ON(twopi > 1 << 18);
     122             : 
     123             :         degrees = (radians * 360) / twopi;
     124             :         tmp = radians - (degrees * twopi) / 360;
     125             : 
     126             :         degrees = (degrees % 360 + 360) % 360;
     127             :         v1 = __fixp_sin32(degrees);
     128             : 
     129             :         v2 = fixp_sin32(degrees + 1);
     130             : 
     131             :         dx = twopi / 360;
     132             :         dy = v2 - v1;
     133             : 
     134             :         tmp *= dy;
     135             : 
     136             :         return v1 +  div_s64(tmp, dx);
     137             : }
     138             : 
     139             : /* cos(x) = sin(x + pi/2 radians) */
     140             : 
     141             : #define fixp_cos32_rad(rad, twopi)      \
     142             :         fixp_sin32_rad(rad + twopi / 4, twopi)
     143             : 
     144             : /**
     145             :  * fixp_linear_interpolate() - interpolates a value from two known points
     146             :  *
     147             :  * @x0: x value of point 0
     148             :  * @y0: y value of point 0
     149             :  * @x1: x value of point 1
     150             :  * @y1: y value of point 1
     151             :  * @x: the linear interpolant
     152             :  */
     153             : static inline int fixp_linear_interpolate(int x0, int y0, int x1, int y1, int x)
     154             : {
     155           0 :         if (y0 == y1 || x == x0)
     156             :                 return y0;
     157           0 :         if (x1 == x0 || x == x1)
     158             :                 return y1;
     159             : 
     160           0 :         return y0 + ((y1 - y0) * (x - x0) / (x1 - x0));
     161             : }
     162             : 
     163             : #endif