Changeset e979fea in mainline for softfloat/generic/mul.c

Timestamp:

2006-02-10T13:43:41Z (19 years ago)

Author:

Josef Cejka <malyzelenyhnus@…>

Branches:

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

Children:

d3ca210

Parents:

e6a40ac

Message:

Fixed some problems with 64 bit arithmetic but others still persisting.

File:

• softfloat/generic/mul.c (modified) (4 diffs)

softfloat/generic/mul.c

@@ -30 +30 @@
 #include<mul.h>
 #include<comparison.h>
+#include<common.h>
 
 /** Multiply two 32 bit float numbers
@@ -218 +219 @@
 
         /* exp is signed so we can easy detect underflow */
-        exp = a.parts.exp + b.parts.exp;
-        exp -= FLOAT64_BIAS;
-        
-        if (exp >= FLOAT64_MAX_EXPONENT) {
-                /* FIXME: overflow */
-                /* set infinity as result */
-                result.binary = FLOAT64_INF;
-                result.parts.sign = a.parts.sign ^ b.parts.sign;
-                return result;
-        };
-        
-        if (exp < 0) { 
-                /* FIXME: underflow */
-                /* return signed zero */
-                result.parts.fraction = 0x0;
-                result.parts.exp = 0x0;
-                return result;
-        };
+        exp = a.parts.exp + b.parts.exp - FLOAT64_BIAS;
         
         frac1 = a.parts.fraction;
+
         if (a.parts.exp > 0) {
                 frac1 |= FLOAT64_HIDDEN_BIT_MASK;
@@ -252 +237 @@
         };
 
-        frac1 <<= 1; /* one bit space for rounding */
+        frac1 <<= (64 - FLOAT64_FRACTION_SIZE - 1);
+        frac2 <<= (64 - FLOAT64_FRACTION_SIZE - 2);
 
         mul64integers(frac1, frac2, &frac1, &frac2);
 
-/* round and return */
-        /* FIXME: ugly soulution is to shift whole frac2 >> as in 32bit version
-         * Here is is more slower because we have to shift two numbers with carry
-         * Better is find first nonzero bit and make only one shift
-         * Third version is to shift both numbers a bit to right and result will be then 
-         * placed in higher part of result. Then lower part will be good only for rounding.
-         */
-        
-        while ((exp < FLOAT64_MAX_EXPONENT) && (frac2 > 0 )) { 
-                frac1 >>= 1;
-                frac1 &= ((frac2 & 0x1) << 63);
-                frac2 >>= 1;
-                ++exp;
-        }
-        
-        while ((exp < FLOAT64_MAX_EXPONENT) && (frac1 >= ( (__u64)1 << (FLOAT64_FRACTION_SIZE + 2)))) { 
-                ++exp;
-                frac1 >>= 1;
-        };
-
-        /* rounding */
-        /* ++frac1;  FIXME: not works - without it is ok */
-        frac1 >>= 1; /* shift off rounding space */
-        
-        if ((exp < FLOAT64_MAX_EXPONENT) && (frac1 >= ((__u64)1 << (FLOAT64_FRACTION_SIZE + 1)))) {
-                ++exp;
-                frac1 >>= 1;
-        };
-
-        if (exp >= FLOAT64_MAX_EXPONENT ) {     
-                /* TODO: fix overflow */
-                /* return infinity*/
-                result.parts.exp = FLOAT64_MAX_EXPONENT;
-                result.parts.fraction = 0x0;
-                return result;
-        }
-        
-        exp -= FLOAT64_FRACTION_SIZE;
-
-        if (exp <= FLOAT64_FRACTION_SIZE) { 
-                /* denormalized number */
-                frac1 >>= 1; /* denormalize */
-                while ((frac1 > 0) && (exp < 0)) {
-                        frac1 >>= 1;
-                        ++exp;
-                };
-                if (frac1 == 0) {
-                        /* FIXME : underflow */
-                result.parts.exp = 0;
-                result.parts.fraction = 0;
-                return result;
-                };
-        };
-        result.parts.exp = exp; 
-        result.parts.fraction = frac1 & ( ((__u64)1 << FLOAT64_FRACTION_SIZE) - 1);
-        
-        return result;  
-        
+        frac2 |= (frac1 != 0);
+        if (frac2 & (0x1ll << 62)) {
+                frac2 <<= 1;
+                exp--;
+        }
+
+        result = finishFloat64(exp, frac2, result.parts.sign);
+        return result;
 }
 
@@ -326 +262 @@
         __u64 low, high, middle1, middle2;
         __u32 alow, blow;
-        
+
         alow = a & 0xFFFFFFFF;
         blow = b & 0xFFFFFFFF;