cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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fixp-arith.h (4290B)

      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
     22static 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 */
     48static inline s32 __fixp_sin32(int degrees)
     49{
     50	s32 ret;
     51	bool negative = false;
     52
     53	if (degrees > 180) {
     54		negative = true;
     55		degrees -= 180;
     56	}
     57	if (degrees > 90)
     58		degrees = 180 - degrees;
     59
     60	ret = sin_table[degrees];
     61
     62	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 */
     72static inline s32 fixp_sin32(int degrees)
     73{
     74	degrees = (degrees % 360 + 360) % 360;
     75
     76	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 */
    112static 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 */
    153static inline int fixp_linear_interpolate(int x0, int y0, int x1, int y1, int x)
    154{
    155	if (y0 == y1 || x == x0)
    156		return y0;
    157	if (x1 == x0 || x == x1)
    158		return y1;
    159
    160	return y0 + ((y1 - y0) * (x - x0) / (x1 - x0));
    161}
    162
    163#endif