WebSVN – HelenOS-historic – Diff – /uspace/trunk/softfloat/generic/mul.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<mul.h>
 #include<comparison.h>
+#include<common.h>
 /** Multiply two 32 bit float numbers
+ *
  */
 float32 mulFloat32(float32 a, float32 b)
+{
     float32 result;
     __u64 frac1, frac2;
     __s32 exp;
     result.parts.sign = a.parts.sign ^ b.parts.sign;
     if (isFloat32NaN(a) || isFloat32NaN(b) ) {
         /* TODO: fix SigNaNs */
         if (isFloat32SigNaN(a)) {
             result.parts.fraction = a.parts.fraction;
             result.parts.exp = a.parts.exp;
             return result;
         };
         if (isFloat32SigNaN(b)) { /* TODO: fix SigNaN */
             result.parts.fraction = b.parts.fraction;
             result.parts.exp = b.parts.exp;
             return result;
         };
         /* set NaN as result */
         result.binary = FLOAT32_NAN;
         return result;
     };
     if (isFloat32Infinity(a)) {
         if (isFloat32Zero(b)) {
             /* FIXME: zero * infinity */
             result.binary = FLOAT32_NAN;
             return result;
+        }
         result.parts.fraction = a.parts.fraction;
         result.parts.exp = a.parts.exp;
         return result;
+    }
     if (isFloat32Infinity(b)) {
         if (isFloat32Zero(a)) {
             /* FIXME: zero * infinity */
             result.binary = FLOAT32_NAN;
             return result;
+        }
         result.parts.fraction = b.parts.fraction;
         result.parts.exp = b.parts.exp;
         return result;
+    }
     /* exp is signed so we can easy detect underflow */
     exp = a.parts.exp + b.parts.exp;
     exp -= FLOAT32_BIAS;
     if (exp >= FLOAT32_MAX_EXPONENT) {
         /* FIXME: overflow */
         /* set infinity as result */
         result.binary = FLOAT32_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;
     };
     frac1 = a.parts.fraction;
     if (a.parts.exp > 0) {
         frac1 |= FLOAT32_HIDDEN_BIT_MASK;
     } else {
         ++exp;
     };
     frac2 = b.parts.fraction;
     if (b.parts.exp > 0) {
         frac2 |= FLOAT32_HIDDEN_BIT_MASK;
     } else {
         ++exp;
     };
     frac1 <<= 1; /* one bit space for rounding */
     frac1 = frac1 * frac2;
 /* round and return */
     while ((exp < FLOAT32_MAX_EXPONENT) && (frac1 >= ( 1 << (FLOAT32_FRACTION_SIZE + 2)))) {
         /* 23 bits of fraction + one more for hidden bit (all shifted 1 bit left)*/
         ++exp;
         frac1 >>= 1;
     };
     /* rounding */
     /* ++frac1; FIXME: not works - without it is ok */
     frac1 >>= 1; /* shift off rounding space */
     if ((exp < FLOAT32_MAX_EXPONENT) && (frac1 >= (1 << (FLOAT32_FRACTION_SIZE + 1)))) {
         ++exp;
         frac1 >>= 1;
     };
     if (exp >= FLOAT32_MAX_EXPONENT ) {
         /* TODO: fix overflow */
         /* return infinity*/
         result.parts.exp = FLOAT32_MAX_EXPONENT;
         result.parts.fraction = 0x0;
         return result;
+    }
     exp -= FLOAT32_FRACTION_SIZE;
     if (exp <= FLOAT32_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 & ( (1 << FLOAT32_FRACTION_SIZE) - 1);
     return result;
+}
 /** Multiply two 64 bit float numbers
+ *
  */
 float64 mulFloat64(float64 a, float64 b)
+{
     float64 result;
     __u64 frac1, frac2;
     __s32 exp;
     result.parts.sign = a.parts.sign ^ b.parts.sign;
     if (isFloat64NaN(a) || isFloat64NaN(b) ) {
         /* TODO: fix SigNaNs */
         if (isFloat64SigNaN(a)) {
             result.parts.fraction = a.parts.fraction;
             result.parts.exp = a.parts.exp;
             return result;
         };
         if (isFloat64SigNaN(b)) { /* TODO: fix SigNaN */
             result.parts.fraction = b.parts.fraction;
             result.parts.exp = b.parts.exp;
             return result;
         };
         /* set NaN as result */
         result.binary = FLOAT64_NAN;
         return result;
     };
     if (isFloat64Infinity(a)) {
         if (isFloat64Zero(b)) {
             /* FIXME: zero * infinity */
             result.binary = FLOAT64_NAN;
             return result;
+        }
         result.parts.fraction = a.parts.fraction;
         result.parts.exp = a.parts.exp;
         return result;
+    }
     if (isFloat64Infinity(b)) {
         if (isFloat64Zero(a)) {
             /* FIXME: zero * infinity */
             result.binary = FLOAT64_NAN;
             return result;
+        }
         result.parts.fraction = b.parts.fraction;
         result.parts.exp = b.parts.exp;
         return result;
+    }
     /* exp is signed so we can easy detect underflow */
-    exp = a.parts.exp + b.parts.exp;
+    exp = a.parts.exp + b.parts.exp - FLOAT64_BIAS;
-    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;
-    };
     frac1 = a.parts.fraction;
     if (a.parts.exp > 0) {
         frac1 |= FLOAT64_HIDDEN_BIT_MASK;
     } else {
         ++exp;
     };
     frac2 = b.parts.fraction;
     if (b.parts.exp > 0) {
         frac2 |= FLOAT64_HIDDEN_BIT_MASK;
     } else {
         ++exp;
     };
-    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;
+    frac2 |= (frac1 != 0);
-        frac1 &= ((frac2 & 0x1) << 63);
+    if (frac2 & (0x1ll << 62)) {
-        frac2 >>= 1;
+        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;
+        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);
+    result = finishFloat64(exp, frac2, result.parts.sign);
     return result;
+}
 /** Multiply two 64 bit numbers and return result in two parts
  * @param a first operand
  * @param b second operand
  * @param lo lower part from result
  * @param hi higher part of result
  */
 void mul64integers(__u64 a,__u64 b, __u64 *lo, __u64 *hi)
+{
     __u64 low, high, middle1, middle2;
     __u32 alow, blow;
     alow = a & 0xFFFFFFFF;
     blow = b & 0xFFFFFFFF;
     a >>= 32;
     b >>= 32;
     low = ((__u64)alow) * blow;
     middle1 = a * blow;
     middle2 = alow * b;
     high = a * b;
     middle1 += middle2;
     high += (((__u64)(middle1 < middle2)) << 32) + (middle1 >> 32);
     middle1 <<= 32;
     low += middle1;
     high += (low < middle1);
     *lo = low;
     *hi = high;
     return;
+}

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(root)/uspace/trunk/softfloat/generic/mul.c – Rev 828 → 829