Changeset d3e241a in mainline for uspace/lib/softfloat/generic/mul.c

Timestamp:

2011-08-06T07:16:50Z (13 years ago)

Author:

Petr Koupy <petr.koupy@…>

Branches:

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

Children:

b705ecc, cc677f1

Parents:

b7ee0369 (diff), c67aff2 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge libposix changes.

File:

• uspace/lib/softfloat/generic/mul.c (modified) (15 diffs)

uspace/lib/softfloat/generic/mul.c

@@ -1 +1 @@
 /*
  * Copyright (c) 2005 Josef Cejka
+ * Copyright (c) 2011 Petr Koupy
  * All rights reserved.
  *
@@ -30 +31 @@
  * @{
  */
-/** @file
+/** @file Multiplication functions.
  */
 
@@ -38 +39 @@
 #include <common.h>
 
-/** Multiply two 32 bit float numbers
- *
+/**
+ * Multiply two single-precision floats.
+ *
+ * @param a First input operand.
+ * @param b Second input operand.
+ * @return Result of multiplication.
  */
 float32 mulFloat32(float32 a, float32 b)
@@ -49 +54 @@
         result.parts.sign = a.parts.sign ^ b.parts.sign;
         
-        if (isFloat32NaN(a) || isFloat32NaN(b) ) {
+        if (isFloat32NaN(a) || isFloat32NaN(b)) {
                 /* TODO: fix SigNaNs */
                 if (isFloat32SigNaN(a)) {
@@ -55 +60 @@
                         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)) { 
@@ -98 +103 @@
                 result.parts.sign = a.parts.sign ^ b.parts.sign;
                 return result;
-        };
+        }
         
         if (exp < 0) { 
@@ -106 +111 @@
                 result.parts.exp = 0x0;
                 return result;
-        };
+        }
         
         frac1 = a.parts.fraction;
@@ -113 +118 @@
         } else {
                 ++exp;
-        };
+        }
         
         frac2 = b.parts.fraction;
@@ -121 +126 @@
         } 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)*/
+
+        /* 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 */
@@ -141 +146 @@
                 ++exp;
                 frac1 >>= 1;
-        };
-
-        if (exp >= FLOAT32_MAX_EXPONENT ) {     
+        }
+
+        if (exp >= FLOAT32_MAX_EXPONENT) {      
                 /* TODO: fix overflow */
                 /* return infinity*/
@@ -159 +164 @@
                         frac1 >>= 1;
                         ++exp;
-                };
+                }
                 if (frac1 == 0) {
                         /* FIXME : underflow */
-                result.parts.exp = 0;
-                result.parts.fraction = 0;
-                return result;
-                };
-        };
+                        result.parts.exp = 0;
+                        result.parts.fraction = 0;
+                        return result;
+                }
+        }
         result.parts.exp = exp; 
-        result.parts.fraction = frac1 & ( (1 << FLOAT32_FRACTION_SIZE) - 1);
+        result.parts.fraction = frac1 & ((1 << FLOAT32_FRACTION_SIZE) - 1);
         
         return result;  
-        
 }
 
-/** Multiply two 64 bit float numbers
- *
+/**
+ * Multiply two double-precision floats.
+ *
+ * @param a First input operand.
+ * @param b Second input operand.
+ * @return Result of multiplication.
  */
 float64 mulFloat64(float64 a, float64 b)
@@ -185 +193 @@
         result.parts.sign = a.parts.sign ^ b.parts.sign;
         
-        if (isFloat64NaN(a) || isFloat64NaN(b) ) {
+        if (isFloat64NaN(a) || isFloat64NaN(b)) {
                 /* TODO: fix SigNaNs */
                 if (isFloat64SigNaN(a)) {
@@ -191 +199 @@
                         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)) { 
@@ -233 +241 @@
         } else {
                 ++exp;
-        };
+        }
         
         frac2 = b.parts.fraction;
@@ -241 +249 @@
         } else {
                 ++exp;
-        };
+        }
 
         frac1 <<= (64 - FLOAT64_FRACTION_SIZE - 1);
         frac2 <<= (64 - FLOAT64_FRACTION_SIZE - 2);
 
-        mul64integers(frac1, frac2, &frac1, &frac2);
-
-        frac2 |= (frac1 != 0);
-        if (frac2 & (0x1ll << 62)) {
-                frac2 <<= 1;
+        mul64(frac1, frac2, &frac1, &frac2);
+
+        frac1 |= (frac2 != 0);
+        if (frac1 & (0x1ll << 62)) {
+                frac1 <<= 1;
                 exp--;
         }
 
-        result = finishFloat64(exp, frac2, result.parts.sign);
+        result = finishFloat64(exp, frac1, 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(uint64_t a,uint64_t b, uint64_t *lo, uint64_t *hi)
+/**
+ * Multiply two quadruple-precision floats.
+ *
+ * @param a First input operand.
+ * @param b Second input operand.
+ * @return Result of multiplication.
+ */
+float128 mulFloat128(float128 a, float128 b)
 {
-        uint64_t low, high, middle1, middle2;
-        uint32_t alow, blow;
-
-        alow = a & 0xFFFFFFFF;
-        blow = b & 0xFFFFFFFF;
-        
-        a >>= 32;
-        b >>= 32;
-        
-        low = ((uint64_t)alow) * blow;
-        middle1 = a * blow;
-        middle2 = alow * b;
-        high = a * b;
-
-        middle1 += middle2;
-        high += (((uint64_t)(middle1 < middle2)) << 32) + (middle1 >> 32);
-        middle1 <<= 32;
-        low += middle1;
-        high += (low < middle1);
-        *lo = low;
-        *hi = high;
-        
-        return;
+        float128 result;
+        uint64_t frac1_hi, frac1_lo, frac2_hi, frac2_lo, tmp_hi, tmp_lo;
+        int32_t exp;
+
+        result.parts.sign = a.parts.sign ^ b.parts.sign;
+
+        if (isFloat128NaN(a) || isFloat128NaN(b)) {
+                /* TODO: fix SigNaNs */
+                if (isFloat128SigNaN(a)) {
+                        result.parts.frac_hi = a.parts.frac_hi;
+                        result.parts.frac_lo = a.parts.frac_lo;
+                        result.parts.exp = a.parts.exp;
+                        return result;
+                }
+                if (isFloat128SigNaN(b)) { /* TODO: fix SigNaN */
+                        result.parts.frac_hi = b.parts.frac_hi;
+                        result.parts.frac_lo = b.parts.frac_lo;
+                        result.parts.exp = b.parts.exp;
+                        return result;
+                }
+                /* set NaN as result */
+                result.binary.hi = FLOAT128_NAN_HI;
+                result.binary.lo = FLOAT128_NAN_LO;
+                return result;
+        }
+
+        if (isFloat128Infinity(a)) {
+                if (isFloat128Zero(b)) {
+                        /* FIXME: zero * infinity */
+                        result.binary.hi = FLOAT128_NAN_HI;
+                        result.binary.lo = FLOAT128_NAN_LO;
+                        return result;
+                }
+                result.parts.frac_hi = a.parts.frac_hi;
+                result.parts.frac_lo = a.parts.frac_lo;
+                result.parts.exp = a.parts.exp;
+                return result;
+        }
+
+        if (isFloat128Infinity(b)) {
+                if (isFloat128Zero(a)) {
+                        /* FIXME: zero * infinity */
+                        result.binary.hi = FLOAT128_NAN_HI;
+                        result.binary.lo = FLOAT128_NAN_LO;
+                        return result;
+                }
+                result.parts.frac_hi = b.parts.frac_hi;
+                result.parts.frac_lo = b.parts.frac_lo;
+                result.parts.exp = b.parts.exp;
+                return result;
+        }
+
+        /* exp is signed so we can easy detect underflow */
+        exp = a.parts.exp + b.parts.exp - FLOAT128_BIAS - 1;
+
+        frac1_hi = a.parts.frac_hi;
+        frac1_lo = a.parts.frac_lo;
+
+        if (a.parts.exp > 0) {
+                or128(frac1_hi, frac1_lo,
+                FLOAT128_HIDDEN_BIT_MASK_HI, FLOAT128_HIDDEN_BIT_MASK_LO,
+                &frac1_hi, &frac1_lo);
+        } else {
+                ++exp;
+        }
+
+        frac2_hi = b.parts.frac_hi;
+        frac2_lo = b.parts.frac_lo;
+
+        if (b.parts.exp > 0) {
+                or128(frac2_hi, frac2_lo,
+                    FLOAT128_HIDDEN_BIT_MASK_HI, FLOAT128_HIDDEN_BIT_MASK_LO,
+                    &frac2_hi, &frac2_lo);
+        } else {
+                ++exp;
+        }
+
+        lshift128(frac2_hi, frac2_lo,
+            128 - FLOAT128_FRACTION_SIZE, &frac2_hi, &frac2_lo);
+
+        tmp_hi = frac1_hi;
+        tmp_lo = frac1_lo;
+        mul128(frac1_hi, frac1_lo, frac2_hi, frac2_lo,
+            &frac1_hi, &frac1_lo, &frac2_hi, &frac2_lo);
+        add128(frac1_hi, frac1_lo, tmp_hi, tmp_lo, &frac1_hi, &frac1_lo);
+        frac2_hi |= (frac2_lo != 0x0ll);
+
+        if ((FLOAT128_HIDDEN_BIT_MASK_HI << 1) <= frac1_hi) {
+                frac2_hi >>= 1;
+                if (frac1_lo & 0x1ll) {
+                        frac2_hi |= (0x1ull < 64);
+                }
+                rshift128(frac1_hi, frac1_lo, 1, &frac1_hi, &frac1_lo);
+                ++exp;
+        }
+
+        result = finishFloat128(exp, frac1_hi, frac1_lo, result.parts.sign, frac2_hi);
+        return result;
 }