aboutsummaryrefslogtreecommitdiff
path: root/contrib/compiler-rt/lib/builtins/ppc/gcc_qadd.c
diff options
context:
space:
mode:
Diffstat (limited to 'contrib/compiler-rt/lib/builtins/ppc/gcc_qadd.c')
-rw-r--r--contrib/compiler-rt/lib/builtins/ppc/gcc_qadd.c76
1 files changed, 76 insertions, 0 deletions
diff --git a/contrib/compiler-rt/lib/builtins/ppc/gcc_qadd.c b/contrib/compiler-rt/lib/builtins/ppc/gcc_qadd.c
new file mode 100644
index 000000000000..32e16e9d1d11
--- /dev/null
+++ b/contrib/compiler-rt/lib/builtins/ppc/gcc_qadd.c
@@ -0,0 +1,76 @@
+/* This file is distributed under the University of Illinois Open Source
+ * License. See LICENSE.TXT for details.
+ */
+
+/* long double __gcc_qadd(long double x, long double y);
+ * This file implements the PowerPC 128-bit double-double add operation.
+ * This implementation is shamelessly cribbed from Apple's DDRT, circa 1993(!)
+ */
+
+#include "DD.h"
+
+long double __gcc_qadd(long double x, long double y)
+{
+ static const uint32_t infinityHi = UINT32_C(0x7ff00000);
+
+ DD dst = { .ld = x }, src = { .ld = y };
+
+ register double A = dst.s.hi, a = dst.s.lo,
+ B = src.s.hi, b = src.s.lo;
+
+ /* If both operands are zero: */
+ if ((A == 0.0) && (B == 0.0)) {
+ dst.s.hi = A + B;
+ dst.s.lo = 0.0;
+ return dst.ld;
+ }
+
+ /* If either operand is NaN or infinity: */
+ const doublebits abits = { .d = A };
+ const doublebits bbits = { .d = B };
+ if ((((uint32_t)(abits.x >> 32) & infinityHi) == infinityHi) ||
+ (((uint32_t)(bbits.x >> 32) & infinityHi) == infinityHi)) {
+ dst.s.hi = A + B;
+ dst.s.lo = 0.0;
+ return dst.ld;
+ }
+
+ /* If the computation overflows: */
+ /* This may be playing things a little bit fast and loose, but it will do for a start. */
+ const double testForOverflow = A + (B + (a + b));
+ const doublebits testbits = { .d = testForOverflow };
+ if (((uint32_t)(testbits.x >> 32) & infinityHi) == infinityHi) {
+ dst.s.hi = testForOverflow;
+ dst.s.lo = 0.0;
+ return dst.ld;
+ }
+
+ double H, h;
+ double T, t;
+ double W, w;
+ double Y;
+
+ H = B + (A - (A + B));
+ T = b + (a - (a + b));
+ h = A + (B - (A + B));
+ t = a + (b - (a + b));
+
+ if (local_fabs(A) <= local_fabs(B))
+ w = (a + b) + h;
+ else
+ w = (a + b) + H;
+
+ W = (A + B) + w;
+ Y = (A + B) - W;
+ Y += w;
+
+ if (local_fabs(a) <= local_fabs(b))
+ w = t + Y;
+ else
+ w = T + Y;
+
+ dst.s.hi = Y = W + w;
+ dst.s.lo = (W - Y) + w;
+
+ return dst.ld;
+}