[SDK] One step further towards ReactOS source code tree restructure: the sdk folder...

[reactos.git] / reactos / lib / sdk / crt / math / sqrt.c

diff --git a/reactos/lib/sdk/crt/math/sqrt.c b/reactos/lib/sdk/crt/math/sqrt.c
deleted file mode 100644 (file)
index 5c257e5..0000000
--- a/reactos/lib/sdk/crt/math/sqrt.c
+++ /dev/null
@@ -1,70 +0,0 @@
-/*
- * COPYRIGHT:       BSD - See COPYING.ARM in the top level directory
- * PROJECT:         ReactOS CRT library
- * PURPOSE:         Portable implementation of sqrt
- * PROGRAMMER:      Timo Kreuzer (timo.kreuzer@reactos.org)
- */
-
-#include <math.h>
-#include <assert.h>
-
-double
-__cdecl
-sqrt(
-    double x)
-{
-    const double threehalfs = 1.5;
-    const double x2 = x * 0.5;
-    long long bits;
-    double inv, y;
-
-    /* Handle special cases */
-    if (x == 0.0)
-    {
-        return x;
-    }
-    else if (x < 0.0)
-    {
-        return -NAN;
-    }
-
-    /* Convert into a 64  bit integer */
-    bits = *(long long *)&x;
-
-    /* Check for !finite(x) */
-    if ((bits & 0x7ff7ffffffffffffLL) == 0x7ff0000000000000LL)
-    {
-        return x;
-    }
-
-    /* Step 1: quick approximation of 1/sqrt(x) with bit magic
-       See http://en.wikipedia.org/wiki/Fast_inverse_square_root */
-    bits = 0x5fe6eb50c7b537a9ll - (bits >> 1);
-    inv = *(double*)&bits;
-
-    /* Step 2: 3 Newton iterations to approximate 1 / sqrt(x) */
-    inv = inv * (threehalfs - (x2 * inv * inv));
-    inv = inv * (threehalfs - (x2 * inv * inv));
-    inv = inv * (threehalfs - (x2 * inv * inv));
-
-    /* Step 3: 1 additional Heron iteration has shown to maximize the precision.
-       Normally the formula would be: y = (y + (x / y)) * 0.5;
-       Instead we use the inverse sqrt directly */
-    y = ((1 / inv) + (x * inv)) * 0.5;
-
-    //assert(y == (double)((y + (x / y)) * 0.5));
-    /* GCC BUG: While the C-Standard requires that an explicit cast to
-       double converts the result of a computation to the appropriate
-       64 bit value, our GCC ignores this and uses an 80 bit FPU register
-       in an intermediate value, so we need to make sure it is stored in
-       a memory location before comparison */
-//#if DBG
-//    {
-//        volatile double y1 = y, y2;
-//        y2 = (y + (x / y)) * 0.5;
-//        assert(y1 == y2);
-//    }
-//#endif
-
-    return y;
-}