#ifndef _FIXP_ARITH_H
#define _FIXP_ARITH_H
+#include <linux/math64.h>
+
/*
* Simplistic fixed-point arithmetics.
* Hmm, I'm probably duplicating some code :(
#include <linux/types.h>
-/* The type representing fixed-point values */
-typedef s16 fixp_t;
+static const s32 sin_table[] = {
+ 0x00000000, 0x023be165, 0x04779632, 0x06b2f1d2, 0x08edc7b6, 0x0b27eb5c,
+ 0x0d61304d, 0x0f996a26, 0x11d06c96, 0x14060b67, 0x163a1a7d, 0x186c6ddd,
+ 0x1a9cd9ac, 0x1ccb3236, 0x1ef74bf2, 0x2120fb82, 0x234815ba, 0x256c6f9e,
+ 0x278dde6e, 0x29ac379f, 0x2bc750e8, 0x2ddf003f, 0x2ff31bdd, 0x32037a44,
+ 0x340ff241, 0x36185aee, 0x381c8bb5, 0x3a1c5c56, 0x3c17a4e7, 0x3e0e3ddb,
+ 0x3fffffff, 0x41ecc483, 0x43d464fa, 0x45b6bb5d, 0x4793a20f, 0x496af3e1,
+ 0x4b3c8c11, 0x4d084650, 0x4ecdfec6, 0x508d9210, 0x5246dd48, 0x53f9be04,
+ 0x55a6125a, 0x574bb8e5, 0x58ea90c2, 0x5a827999, 0x5c135399, 0x5d9cff82,
+ 0x5f1f5ea0, 0x609a52d1, 0x620dbe8a, 0x637984d3, 0x64dd894f, 0x6639b039,
+ 0x678dde6d, 0x68d9f963, 0x6a1de735, 0x6b598ea1, 0x6c8cd70a, 0x6db7a879,
+ 0x6ed9eba0, 0x6ff389de, 0x71046d3c, 0x720c8074, 0x730baeec, 0x7401e4bf,
+ 0x74ef0ebb, 0x75d31a5f, 0x76adf5e5, 0x777f903b, 0x7847d908, 0x7906c0af,
+ 0x79bc384c, 0x7a6831b8, 0x7b0a9f8c, 0x7ba3751c, 0x7c32a67c, 0x7cb82884,
+ 0x7d33f0c8, 0x7da5f5a3, 0x7e0e2e31, 0x7e6c924f, 0x7ec11aa3, 0x7f0bc095,
+ 0x7f4c7e52, 0x7f834ecf, 0x7fb02dc4, 0x7fd317b3, 0x7fec09e1, 0x7ffb025e,
+ 0x7fffffff
+};
-#define FRAC_N 8
-#define FRAC_MASK ((1<<FRAC_N)-1)
+/**
+ * __fixp_sin32() returns the sin of an angle in degrees
+ *
+ * @degrees: angle, in degrees, from 0 to 360.
+ *
+ * The returned value ranges from -0x7fffffff to +0x7fffffff.
+ */
+static inline s32 __fixp_sin32(int degrees)
+{
+ s32 ret;
+ bool negative = false;
-/* Not to be used directly. Use fixp_{cos,sin} */
-static const fixp_t cos_table[46] = {
- 0x0100, 0x00FF, 0x00FF, 0x00FE, 0x00FD, 0x00FC, 0x00FA, 0x00F8,
- 0x00F6, 0x00F3, 0x00F0, 0x00ED, 0x00E9, 0x00E6, 0x00E2, 0x00DD,
- 0x00D9, 0x00D4, 0x00CF, 0x00C9, 0x00C4, 0x00BE, 0x00B8, 0x00B1,
- 0x00AB, 0x00A4, 0x009D, 0x0096, 0x008F, 0x0087, 0x0080, 0x0078,
- 0x0070, 0x0068, 0x005F, 0x0057, 0x004F, 0x0046, 0x003D, 0x0035,
- 0x002C, 0x0023, 0x001A, 0x0011, 0x0008, 0x0000
-};
+ if (degrees > 180) {
+ negative = true;
+ degrees -= 180;
+ }
+ if (degrees > 90)
+ degrees = 180 - degrees;
+ ret = sin_table[degrees];
-/* a: 123 -> 123.0 */
-static inline fixp_t fixp_new(s16 a)
-{
- return a<<FRAC_N;
+ return negative ? -ret : ret;
}
-/* a: 0xFFFF -> -1.0
- 0x8000 -> 1.0
- 0x0000 -> 0.0
-*/
-static inline fixp_t fixp_new16(s16 a)
+/**
+ * fixp_sin32() returns the sin of an angle in degrees
+ *
+ * @degrees: angle, in degrees. The angle can be positive or negative
+ *
+ * The returned value ranges from -0x7fffffff to +0x7fffffff.
+ */
+static inline s32 fixp_sin32(int degrees)
{
- return ((s32)a)>>(16-FRAC_N);
+ degrees = (degrees % 360 + 360) % 360;
+
+ return __fixp_sin32(degrees);
}
-static inline fixp_t fixp_cos(unsigned int degrees)
+/* cos(x) = sin(x + 90 degrees) */
+#define fixp_cos32(v) fixp_sin32((v) + 90)
+
+/*
+ * 16 bits variants
+ *
+ * The returned value ranges from -0x7fff to 0x7fff
+ */
+
+#define fixp_sin16(v) (fixp_sin32(v) >> 16)
+#define fixp_cos16(v) (fixp_cos32(v) >> 16)
+
+/**
+ * fixp_sin32_rad() - calculates the sin of an angle in radians
+ *
+ * @radians: angle, in radians
+ * @twopi: value to be used for 2*pi
+ *
+ * Provides a variant for the cases where just 360
+ * values is not enough. This function uses linear
+ * interpolation to a wider range of values given by
+ * twopi var.
+ *
+ * Experimental tests gave a maximum difference of
+ * 0.000038 between the value calculated by sin() and
+ * the one produced by this function, when twopi is
+ * equal to 360000. That seems to be enough precision
+ * for practical purposes.
+ *
+ * Please notice that two high numbers for twopi could cause
+ * overflows, so the routine will not allow values of twopi
+ * bigger than 1^18.
+ */
+static inline s32 fixp_sin32_rad(u32 radians, u32 twopi)
{
- int quadrant = (degrees / 90) & 3;
- unsigned int i = degrees % 90;
+ int degrees;
+ s32 v1, v2, dx, dy;
+ s64 tmp;
- if (quadrant == 1 || quadrant == 3)
- i = 90 - i;
+ /*
+ * Avoid too large values for twopi, as we don't want overflows.
+ */
+ BUG_ON(twopi > 1 << 18);
- i >>= 1;
+ degrees = (radians * 360) / twopi;
+ tmp = radians - (degrees * twopi) / 360;
- return (quadrant == 1 || quadrant == 2)? -cos_table[i] : cos_table[i];
-}
+ degrees = (degrees % 360 + 360) % 360;
+ v1 = __fixp_sin32(degrees);
-static inline fixp_t fixp_sin(unsigned int degrees)
-{
- return -fixp_cos(degrees + 90);
-}
+ v2 = fixp_sin32(degrees + 1);
-static inline fixp_t fixp_mult(fixp_t a, fixp_t b)
-{
- return ((s32)(a*b))>>FRAC_N;
+ dx = twopi / 360;
+ dy = v2 - v1;
+
+ tmp *= dy;
+
+ return v1 + div_s64(tmp, dx);
}
+/* cos(x) = sin(x + pi/2 radians) */
+
+#define fixp_cos32_rad(rad, twopi) \
+ fixp_sin32_rad(rad + twopi / 4, twopi)
+
#endif
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