Alex Crichton
d166a30c11
* Move everything to azure pipelines * Inline docker configuration in this repo (no `cross`) * Delete `no-panic` example, use `#[no_panic]` instead.
88 lines
2.6 KiB
Rust
88 lines
2.6 KiB
Rust
/* origin: FreeBSD /usr/src/lib/msun/src/e_atan2f.c */
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/*
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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use super::atanf;
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use super::fabsf;
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const PI: f32 = 3.1415927410e+00; /* 0x40490fdb */
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const PI_LO: f32 = -8.7422776573e-08; /* 0xb3bbbd2e */
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#[inline]
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#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
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pub fn atan2f(y: f32, x: f32) -> f32 {
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if x.is_nan() || y.is_nan() {
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return x + y;
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}
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let mut ix = x.to_bits();
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let mut iy = y.to_bits();
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if ix == 0x3f800000 {
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/* x=1.0 */
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return atanf(y);
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}
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let m = ((iy >> 31) & 1) | ((ix >> 30) & 2); /* 2*sign(x)+sign(y) */
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ix &= 0x7fffffff;
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iy &= 0x7fffffff;
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/* when y = 0 */
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if iy == 0 {
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return match m {
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0 | 1 => y, /* atan(+-0,+anything)=+-0 */
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2 => PI, /* atan(+0,-anything) = pi */
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3 | _ => -PI, /* atan(-0,-anything) =-pi */
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};
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}
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/* when x = 0 */
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if ix == 0 {
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return if m & 1 != 0 { -PI / 2. } else { PI / 2. };
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}
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/* when x is INF */
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if ix == 0x7f800000 {
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return if iy == 0x7f800000 {
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match m {
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0 => PI / 4., /* atan(+INF,+INF) */
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1 => -PI / 4., /* atan(-INF,+INF) */
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2 => 3. * PI / 4., /* atan(+INF,-INF)*/
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3 | _ => -3. * PI / 4., /* atan(-INF,-INF)*/
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}
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} else {
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match m {
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0 => 0., /* atan(+...,+INF) */
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1 => -0., /* atan(-...,+INF) */
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2 => PI, /* atan(+...,-INF) */
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3 | _ => -PI, /* atan(-...,-INF) */
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}
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};
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}
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/* |y/x| > 0x1p26 */
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if (ix + (26 << 23) < iy) || (iy == 0x7f800000) {
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return if m & 1 != 0 { -PI / 2. } else { PI / 2. };
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}
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/* z = atan(|y/x|) with correct underflow */
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let z = if (m & 2 != 0) && (iy + (26 << 23) < ix) {
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/*|y/x| < 0x1p-26, x < 0 */
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0.
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} else {
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atanf(fabsf(y / x))
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};
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match m {
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0 => z, /* atan(+,+) */
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1 => -z, /* atan(-,+) */
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2 => PI - (z - PI_LO), /* atan(+,-) */
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_ => (z - PI_LO) - PI, /* case 3 */ /* atan(-,-) */
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}
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}
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