WebSVN – HelenOS – Diff – /uspace/trunk/softfloat/generic/arithmetic.c

 /*
  * Copyright (C) 2005 Josef Cejka
  * All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  * - Redistributions in binary form must reproduce the above copyright
  *   notice, this list of conditions and the following disclaimer in the
  *   documentation and/or other materials provided with the distribution.
  * - The name of the author may not be used to endorse or promote products
  *   derived from this software without specific prior written permission.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include<sftypes.h>
 #include<arithmetic.h>
 #include<comparison.h>
 /** Add two Float32 numbers with same signs
  */
 float32 addFloat32(float32 a, float32 b)
+{
     int expdiff;
     __u32 exp1,exp2,mant1,mant2;
     expdiff=a.parts.exp - b.parts.exp;
     if (expdiff<0) {
         if (isFloat32NaN(b)) {
             //TODO: fix SigNaN
             if (isFloat32SigNaN(b)) {
             };
             return b;
         };
         if (b.parts.exp==0xFF) {
             return b;
+        }
         mant1=b.parts.mantisa;
         exp1=b.parts.exp;
         mant2=a.parts.mantisa;
         exp2=a.parts.exp;
         expdiff*=-1;
     } else {
         if (isFloat32NaN(a)) {
             //TODO: fix SigNaN
             if ((isFloat32SigNaN(a))||(isFloat32SigNaN(b))) {
             };
             return a;
         };
         if (a.parts.exp==0xFF) {
             return a;
+        }
         mant1=a.parts.mantisa;
         exp1=a.parts.exp;
         mant2=b.parts.mantisa;
         exp2=b.parts.exp;
     };
     if (exp1==0) {
         //both are denormalized
         mant1+=mant2;
         if (mant1&0xF00000) {
             a.parts.exp=1;
         };
         a.parts.mantisa=mant1;
         return a;
     };
     // create some space for rounding
     mant1<<=6;
     mant2<<=6;
     mant1|=0x20000000; //add hidden bit
     if (exp2==0) {
         --expdiff;
     } else {
         mant2|=0x20000000; //hidden bit
     };
     if (expdiff>24) {
          goto done;
          };
     mant2>>=expdiff;
     mant1+=mant2;
 done:
     if (mant1&0x40000000) {
         ++exp1;
         mant1>>=1;
     };
     //rounding - if first bit after mantisa is set then round up
     mant1+=0x20;
+    if (mant1&0x40000000) {
+        ++exp1;
+        mant1>>=1;
+    };
     a.parts.exp=exp1;
-    a.parts.mantisa=mant1>>6;
+    a.parts.mantisa = ((mant1&(~0x20000000))>>6); /*Clear hidden bit and shift */
     return a;
 };
-/** Substract two float32 numbers with same signs
+/** Subtract two float32 numbers with same signs
  */
 float32 subFloat32(float32 a, float32 b)
+{
+    int expdiff;
+    __u32 exp1,exp2,mant1,mant2;
+    float32 result;
+    result.f = 0;
+    expdiff=a.parts.exp - b.parts.exp;
+    if ((expdiff<0)||((expdiff==0)&&(a.parts.mantisa<b.parts.mantisa))) {
+        if (isFloat32NaN(b)) {
+            //TODO: fix SigNaN
+            if (isFloat32SigNaN(b)) {
+            };
+            return b;
+        };
+        if (b.parts.exp==0xFF) {
+            b.parts.sign=!b.parts.sign; /* num -(+-inf) = -+inf */
+            return b;
+        }
+        result.parts.sign = !a.parts.sign;
+        mant1=b.parts.mantisa;
+        exp1=b.parts.exp;
+        mant2=a.parts.mantisa;
+        exp2=a.parts.exp;
+        expdiff*=-1;
+    } else {
+        if (isFloat32NaN(a)) {
+            //TODO: fix SigNaN
+            if ((isFloat32SigNaN(a))||(isFloat32SigNaN(b))) {
+            };
+            return a;
+        };
+        if (a.parts.exp==0xFF) {
+            if (b.parts.exp==0xFF) {
+                /* inf - inf => nan */
+                //TODO: fix exception
+                result.binary = FLOAT32_NAN;
+                return result;
+            };
+            return a;
+        }
+        result.parts.sign = a.parts.sign;
+        mant1=a.parts.mantisa;
+        exp1=a.parts.exp;
+        mant2=b.parts.mantisa;
+        exp2=b.parts.exp;
+    };
+    if (exp1==0) {
+        //both are denormalized
+        result.parts.mantisa=mant1-mant2;
+        if (result.parts.mantisa>mant1) {
+            //TODO: underflow exception
+            return result;
+        };
+        result.parts.exp=0;
+        return result;
+    };
+    // create some space for rounding
+    mant1<<=6;
+    mant2<<=6;
+    mant1|=0x20000000; //add hidden bit
+    if (exp2==0) {
+        --expdiff;
+    } else {
+        mant2|=0x20000000; //hidden bit
+    };
+    if (expdiff>24) {
+         goto done;
+         };
+    mant1 = mant1-(mant2>>expdiff);
+done:
+    //TODO: find first nonzero digit and shift result and detect possibly underflow
+    while ((exp1>0)&&(!(mant1&0x20000000))) {
+        exp1--;
+        mant1 <<= 1;
+        if(mant1 == 0) {
+            /* Realy is it an underflow? ... */
+            //TODO: fix underflow
+        };
+    };
+    //rounding - if first bit after mantisa is set then round up
+    mant1 += 0x20;
+    if (mant1&0x40000000) {
+        ++exp1;
+        mant1>>=1;
+    };
+    result.parts.mantisa = ((mant1&(~0x20000000))>>6); /*Clear hidden bit and shift */
+    result.parts.exp = exp1;
+    return result;
 };

Subversion Repositories HelenOS

(root)/uspace/trunk/softfloat/generic/arithmetic.c – Rev 660 → 661