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Unified Diff: fusl/src/math/atan2f.c

Issue 1573973002: Add a "fork" of musl as //fusl. (Closed) Base URL: https://github.com/domokit/mojo.git@master
Patch Set: Created 4 years, 11 months ago
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Index: fusl/src/math/atan2f.c
diff --git a/fusl/src/math/atan2f.c b/fusl/src/math/atan2f.c
new file mode 100644
index 0000000000000000000000000000000000000000..c634d00fc93195f63d25b59c0ae6e4a0e8e826d2
--- /dev/null
+++ b/fusl/src/math/atan2f.c
@@ -0,0 +1,83 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/e_atan2f.c */
+/*
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+#include "libm.h"
+
+static const float
+pi = 3.1415927410e+00, /* 0x40490fdb */
+pi_lo = -8.7422776573e-08; /* 0xb3bbbd2e */
+
+float atan2f(float y, float x)
+{
+ float z;
+ uint32_t m,ix,iy;
+
+ if (isnan(x) || isnan(y))
+ return x+y;
+ GET_FLOAT_WORD(ix, x);
+ GET_FLOAT_WORD(iy, y);
+ if (ix == 0x3f800000) /* x=1.0 */
+ return atanf(y);
+ m = ((iy>>31)&1) | ((ix>>30)&2); /* 2*sign(x)+sign(y) */
+ ix &= 0x7fffffff;
+ iy &= 0x7fffffff;
+
+ /* when y = 0 */
+ if (iy == 0) {
+ switch (m) {
+ case 0:
+ case 1: return y; /* atan(+-0,+anything)=+-0 */
+ case 2: return pi; /* atan(+0,-anything) = pi */
+ case 3: return -pi; /* atan(-0,-anything) =-pi */
+ }
+ }
+ /* when x = 0 */
+ if (ix == 0)
+ return m&1 ? -pi/2 : pi/2;
+ /* when x is INF */
+ if (ix == 0x7f800000) {
+ if (iy == 0x7f800000) {
+ switch (m) {
+ case 0: return pi/4; /* atan(+INF,+INF) */
+ case 1: return -pi/4; /* atan(-INF,+INF) */
+ case 2: return 3*pi/4; /*atan(+INF,-INF)*/
+ case 3: return -3*pi/4; /*atan(-INF,-INF)*/
+ }
+ } else {
+ switch (m) {
+ case 0: return 0.0f; /* atan(+...,+INF) */
+ case 1: return -0.0f; /* atan(-...,+INF) */
+ case 2: return pi; /* atan(+...,-INF) */
+ case 3: return -pi; /* atan(-...,-INF) */
+ }
+ }
+ }
+ /* |y/x| > 0x1p26 */
+ if (ix+(26<<23) < iy || iy == 0x7f800000)
+ return m&1 ? -pi/2 : pi/2;
+
+ /* z = atan(|y/x|) with correct underflow */
+ if ((m&2) && iy+(26<<23) < ix) /*|y/x| < 0x1p-26, x < 0 */
+ z = 0.0;
+ else
+ z = atanf(fabsf(y/x));
+ switch (m) {
+ case 0: return z; /* atan(+,+) */
+ case 1: return -z; /* atan(-,+) */
+ case 2: return pi - (z-pi_lo); /* atan(+,-) */
+ default: /* case 3 */
+ return (z-pi_lo) - pi; /* atan(-,-) */
+ }
+}
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