Changeset 7afd2aca in mainline for softfloat/generic/softfloat.c

Timestamp:

2005-12-07T22:37:49Z (20 years ago)

Author:

Josef Cejka <malyzelenyhnus@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

36aee474

Parents:

ebff5e8

Message:

Softfloat: 32 bit float addition completed.

File:

• softfloat/generic/softfloat.c (modified) (8 diffs)

softfloat/generic/softfloat.c

@@ -30 +30 @@
 #include<softfloat.h>
 
+float32 addFloat32(float32 a, float32 b);
+float32 subFloat32(float32 a, float32 b);
+inline int isFloat32NaN(float32 f);
+inline int isFloat32SigNaN(float32 f);
 
 float __addsf3(float a, float b)
 {
         float32 fa, fb;
-        a.f=a;
-        b.f=b;
-        if (a.parts.sign!=b.parts.sign) return subFloat32(a,b).f;
-        return addFloat32(a,b).f;
+        fa.f=a;
+        fb.f=b;
+        if (fa.parts.sign!=fb.parts.sign) return subFloat32(fa,fb).f;
+        return addFloat32(fa,fb).f;
 };
 
@@ -43 +47 @@
 {
         float32 fa, fb;
-        a.f=a;
-        b.f=b;
-        if (a.parts.sign!=b.parts.sign) return addFloat32(a,b).f;
-        return subFloat32(a,b).f;
+        fa.f=a;
+        fb.f=b;
+        if (fa.parts.sign!=fb.parts.sign) return addFloat32(fa,fb).f;
+        return subFloat32(fa,fb).f;
 };
 
@@ -60 +64 @@
 {
         float64 fa;
-        fa.f=a;
+        fa.d=a;
         fa.parts.sign=!fa.parts.sign;
-        return fa.f;
+        return fa.d;
 };
 
+/** Add two Float32 numbers with same signs
+ */
 float32 addFloat32(float32 a, float32 b)
 {
-        __u32 expdiff;
+        int expdiff;
         __u32 exp1,exp2,mant1,mant2;
         
         expdiff=a.parts.exp - b.parts.exp;
         if (expdiff<0) {
-                if (isFloat32NaN(a)) {
-                        //TODO: fix it
-                        return a;
+                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;
@@ -83 +95 @@
                 expdiff*=-1;
         } else {
-                if (isFloat32NaN(b)) {
-                        //TODO: fix it
-                        return b;
+                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;
@@ -92 +111 @@
                 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;
         
-        if (exp1!=0) {
-                mant1|=0x20000000; //add hidden bit
-        };
+        mant1|=0x20000000; //add hidden bit
+        
         
         if (exp2==0) {
@@ -107 +135 @@
         };
         
-        
-        if (expdiff>24) {
-                goto done; 
-        };
-        
         mant2>>=expdiff;
         mant1+=mant2;
 done:
-        //TODO: round mant1
+        if (mant1&0x40000000) {
+                ++exp1;
+                mant1>>=1;
+        };
+        
+        //rounding - if first bit after mantisa is set then round up
+        mant1+=0x20;
+        
         a.parts.exp=exp1;
         a.parts.mantisa=mant1>>6;
@@ -121 +151 @@
 };
 
+/** Substract two float32 numbers with same signs
+ */
 float32 subFloat32(float32 a, float32 b)
 {
@@ -129 +161 @@
 inline int isFloat32NaN(float32 f)
 {       /* NaN : exp = 0xff and nonzero mantisa */
-        float32 fa;
-        fa.f=f;
-        return ((fa.parts.exp==0xFF)&&(fa.parts.mantisa));
+        return ((f.parts.exp==0xFF)&&(f.parts.mantisa));
 };
 
 inline int isFloat32SigNaN(float32 f)
 {       /* SigNaN : exp = 0xff mantisa = 1xxxxx..x (binary), where at least one x is nonzero */
-        float32 fa;
-        fa.f=f;
-        return ((fa.parts.exp==0xFF)&&(fa.parts.mantisa>0x400000));
+        return ((f.parts.exp==0xFF)&&(f.parts.mantisa>0x400000));
 };