added softfloat16.cc

2011-06-11 13:16:53 +00:00 · 2011-06-11 13:16:53 +00:00 · 307e5b7db5
commit 307e5b7db5
parent 79b1252552
1 changed files with 127 additions and 0 deletions
--- a/bochs/fpu/softfloat16.cc
+++ b/bochs/fpu/softfloat16.cc
@ -0,0 +1,127 @@
+/*============================================================================
+This C source file is part of the SoftFloat IEC/IEEE Floating-point Arithmetic
+Package, Release 2b.
+
+Written by John R. Hauser.  This work was made possible in part by the
+International Computer Science Institute, located at Suite 600, 1947 Center
+Street, Berkeley, California 94704.  Funding was partially provided by the
+National Science Foundation under grant MIP-9311980.  The original version
+of this code was written as part of a project to build a fixed-point vector
+processor in collaboration with the University of California at Berkeley,
+overseen by Profs. Nelson Morgan and John Wawrzynek.  More information
+is available through the Web page `http://www.cs.berkeley.edu/~jhauser/
+arithmetic/SoftFloat.html'.
+
+THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE.  Although reasonable effort has
+been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT TIMES
+RESULT IN INCORRECT BEHAVIOR.  USE OF THIS SOFTWARE IS RESTRICTED TO PERSONS
+AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ALL LOSSES,
+COSTS, OR OTHER PROBLEMS THEY INCUR DUE TO THE SOFTWARE, AND WHO FURTHERMORE
+EFFECTIVELY INDEMNIFY JOHN HAUSER AND THE INTERNATIONAL COMPUTER SCIENCE
+INSTITUTE (possibly via similar legal warning) AGAINST ALL LOSSES, COSTS, OR
+OTHER PROBLEMS INCURRED BY THEIR CUSTOMERS AND CLIENTS DUE TO THE SOFTWARE.
+
+Derivative works are acceptable, even for commercial purposes, so long as
+(1) the source code for the derivative work includes prominent notice that
+the work is derivative, and (2) the source code includes prominent notice with
+these four paragraphs for those parts of this code that are retained.
+=============================================================================*/
+
+/*============================================================================
+ * Adapted for Bochs (x86 achitecture simulator) by
+ *            Stanislav Shwartsman [sshwarts at sourceforge net]
+ * ==========================================================================*/
+
+#include "softfloat.h"
+
+#ifdef FLOAT16
+
+#include "softfloat-round-pack.h"
+#include "softfloat-specialize.h"
+#include "softfloat-macros.h"
+
+/*----------------------------------------------------------------------------
+| Determine half-precision floating-point number class
+*----------------------------------------------------------------------------*/
+
+float_class_t float16_class(float16 a)
+{
+   Bit16s aExp = extractFloat16Exp(a);
+   Bit16u aSig = extractFloat16Frac(a);
+   int  aSign = extractFloat16Sign(a);
+
+   if(aExp == 0x1F) {
+       if (aSig == 0)
+           return (aSign) ? float_negative_inf : float_positive_inf;
+
+       return float_NaN;
+   }
+
+   if(aExp == 0) {
+       if (aSig == 0) return float_zero;
+       return float_denormal;
+   }
+
+   return float_normalized;
+}
+
+/*----------------------------------------------------------------------------
+| Returns the result of converting the half-precision floating-point value
+| `a' to the single-precision floating-point format.  The conversion is
+| performed according to the IEC/IEEE Standard for Binary Floating-Point
+| Arithmetic.
+*----------------------------------------------------------------------------*/
+
+float32 float16_to_float32(float16 a, float_status_t &status)
+{
+    Bit16u aSig = extractFloat16Frac(a);
+    Bit16s aExp = extractFloat16Exp(a);
+    int aSign = extractFloat16Sign(a);
+
+    if (aExp == 0x1F) {
+        if (aSig) return commonNaNToFloat32(float16ToCommonNaN(a, status));
+        return packFloat32(aSign, 0xFF, 0);
+    }
+    if (aExp == 0) {
+        if (aSig == 0) return packFloat32(aSign, 0, 0);
+        float_raise(status, float_flag_denormal);
+        normalizeFloat16Subnormal(aSig, &aExp, &aSig);
+        --aExp;
+    }
+
+    return packFloat32(aSign, aExp + 0x70, ((Bit32u) aSig)<<13);
+}
+
+/*----------------------------------------------------------------------------
+| Returns the result of converting the single-precision floating-point value
+| `a' to the half-precision floating-point format.  The conversion is
+| performed according to the IEC/IEEE Standard for Binary Floating-Point
+| Arithmetic.
+*----------------------------------------------------------------------------*/
+
+float16 float32_to_float16(float32 a, float_status_t &status)
+{
+    Bit32u aSig = extractFloat32Frac(a);
+    Bit16s aExp = extractFloat32Exp(a);
+    int aSign = extractFloat32Sign(a);
+
+    if (aExp == 0xFF) {
+        if (aSig) return commonNaNToFloat16(float32ToCommonNaN(a, status));
+        return packFloat16(aSign, 0x1F, 0);
+    }
+    if (aExp == 0) {
+        if (aSig == 0) return packFloat16(aSign, 0, 0);
+        float_raise(status, float_flag_denormal);
+    }
+
+    aSig = shift32RightJamming(aSig, 9);
+    Bit16u zSig = (Bit16u) aSig;
+    if (aExp || zSig) {
+        zSig |= 0x4000;
+        aExp -= 0x71;
+    }
+
+    return roundAndPackFloat16(aSign, aExp, zSig, status);
+}
+
+#endif