ntdll: Use the atan2() implementation from the bundled musl library.

dlls/ntdll/math.c

@@ -577,79 +577,6 @@ int CDECL abs( int i )
 }
 
 /*********************************************************************
- *                  atan2   (NTDLL.@)
- *
- * Copied from musl: src/math/atan2.c
- */
-double CDECL atan2( double y, double x )
-{
-    static const double pi     = 3.1415926535897931160E+00,
-                 pi_lo  = 1.2246467991473531772E-16;
-
-    double z;
-    unsigned int m, lx, ly, ix, iy;
-
-    if (isnan(x) || isnan(y))
-        return x+y;
-    ix = *(ULONGLONG*)&x >> 32;
-    lx = *(ULONGLONG*)&x;
-    iy = *(ULONGLONG*)&y >> 32;
-    ly = *(ULONGLONG*)&y;
-    if (((ix - 0x3ff00000) | lx) == 0)  /* x = 1.0 */
-        return atan(y);
-    m = ((iy >> 31) & 1) | ((ix >> 30) & 2);  /* 2*sign(x)+sign(y) */
-    ix = ix & 0x7fffffff;
-    iy = iy & 0x7fffffff;
-
-    /* when y = 0 */
-    if ((iy | ly) == 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 | lx) == 0)
-        return m & 1 ? -pi / 2 : pi / 2;
-    /* when x is INF */
-    if (ix == 0x7ff00000) {
-        if (iy == 0x7ff00000) {
-            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 0.0;  /* atan(+...,+INF) */
-            case 1: return -0.0; /* atan(-...,+INF) */
-            case 2: return pi;   /* atan(+...,-INF) */
-            case 3: return -pi;  /* atan(-...,-INF) */
-            }
-        }
-    }
-    /* |y/x| > 0x1p64 */
-    if (ix + (64 << 20) < iy || iy == 0x7ff00000)
-        return m & 1 ? -pi / 2 : pi / 2;
-
-    /* z = atan(|y/x|) without spurious underflow */
-    if ((m & 2) && iy + (64 << 20) < ix)  /* |y/x| < 0x1p-64, x<0 */
-        z = 0;
-    else
-        z = atan(fabs(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(-,-) */
-    }
-}
-
-/*********************************************************************
  *                  ceil   (NTDLL.@)
  *
  * Based on musl: src/math/ceilf.c