Initial import of compiler-rt.
-
llvm-svn: 74292
diff --git a/compiler-rt/lib/floatuntixf.c b/compiler-rt/lib/floatuntixf.c
new file mode 100644
index 0000000..a28db10
--- /dev/null
+++ b/compiler-rt/lib/floatuntixf.c
@@ -0,0 +1,80 @@
+//===-- floatuntixf.c - Implement __floatuntixf ---------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __floatuntixf for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#if __x86_64
+
+#include "int_lib.h"
+#include <float.h>
+
+// Returns: convert a to a long double, rounding toward even.
+
+// Assumption: long double is a IEEE 80 bit floating point type padded to 128 bits
+// tu_int is a 128 bit integral type
+
+// gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee eeee |
+// 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm
+
+si_int __clzti2(ti_int a);
+
+long double
+__floatuntixf(tu_int a)
+{
+ if (a == 0)
+ return 0.0;
+ const unsigned N = sizeof(tu_int) * CHAR_BIT;
+ int sd = N - __clzti2(a); // number of significant digits
+ int e = sd - 1; // exponent
+ if (sd > LDBL_MANT_DIG)
+ {
+ // start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
+ // finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
+ // 12345678901234567890123456
+ // 1 = msb 1 bit
+ // P = bit LDBL_MANT_DIG-1 bits to the right of 1
+ // Q = bit LDBL_MANT_DIG bits to the right of 1
+ // R = "or" of all bits to the right of Q
+ switch (sd)
+ {
+ case LDBL_MANT_DIG + 1:
+ a <<= 1;
+ break;
+ case LDBL_MANT_DIG + 2:
+ break;
+ default:
+ a = (a >> (sd - (LDBL_MANT_DIG+2))) |
+ ((a & ((tu_int)(-1) >> ((N + LDBL_MANT_DIG+2) - sd))) != 0);
+ };
+ // finish:
+ a |= (a & 4) != 0; // Or P into R
+ ++a; // round - this step may add a significant bit
+ a >>= 2; // dump Q and R
+ // a is now rounded to LDBL_MANT_DIG or LDBL_MANT_DIG+1 bits
+ if (a & ((tu_int)1 << LDBL_MANT_DIG))
+ {
+ a >>= 1;
+ ++e;
+ }
+ // a is now rounded to LDBL_MANT_DIG bits
+ }
+ else
+ {
+ a <<= (LDBL_MANT_DIG - sd);
+ // a is now rounded to LDBL_MANT_DIG bits
+ }
+ long_double_bits fb;
+ fb.u.high.low = (e + 16383); // exponent
+ fb.u.low.all = (du_int)a; // mantissa
+ return fb.f;
+}
+
+#endif