Initial import of compiler-rt.
-
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@74292 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/floatdisf.c b/lib/floatdisf.c
new file mode 100644
index 0000000..5a92848
--- /dev/null
+++ b/lib/floatdisf.c
@@ -0,0 +1,76 @@
+//===-- floatdisf.c - Implement __floatdisf -------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __floatdisf for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "int_lib.h"
+#include <float.h>
+
+// Returns: convert a to a float, rounding toward even.
+
+// Assumption: float is a IEEE 32 bit floating point type
+// di_int is a 64 bit integral type
+
+// seee eeee emmm mmmm mmmm mmmm mmmm mmmm
+
+float
+__floatdisf(di_int a)
+{
+ if (a == 0)
+ return 0.0F;
+ const unsigned N = sizeof(di_int) * CHAR_BIT;
+ const di_int s = a >> (N-1);
+ a = (a ^ s) - s;
+ int sd = N - __builtin_clzll(a); // number of significant digits
+ int e = sd - 1; // exponent
+ if (sd > FLT_MANT_DIG)
+ {
+ // start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
+ // finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
+ // 12345678901234567890123456
+ // 1 = msb 1 bit
+ // P = bit FLT_MANT_DIG-1 bits to the right of 1
+ // Q = bit FLT_MANT_DIG bits to the right of 1
+ // R = "or" of all bits to the right of Q
+ switch (sd)
+ {
+ case FLT_MANT_DIG + 1:
+ a <<= 1;
+ break;
+ case FLT_MANT_DIG + 2:
+ break;
+ default:
+ a = ((du_int)a >> (sd - (FLT_MANT_DIG+2))) |
+ ((a & ((du_int)(-1) >> ((N + FLT_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 FLT_MANT_DIG or FLT_MANT_DIG+1 bits
+ if (a & ((du_int)1 << FLT_MANT_DIG))
+ {
+ a >>= 1;
+ ++e;
+ }
+ // a is now rounded to FLT_MANT_DIG bits
+ }
+ else
+ {
+ a <<= (FLT_MANT_DIG - sd);
+ // a is now rounded to FLT_MANT_DIG bits
+ }
+ float_bits fb;
+ fb.u = ((su_int)s & 0x80000000) | // sign
+ ((e + 127) << 23) | // exponent
+ ((su_int)a & 0x007FFFFF); // mantissa
+ return fb.f;
+}