--- a/src/simulator/high-precision-128.cc Wed Apr 22 17:22:41 2009 +0200
+++ b/src/simulator/high-precision-128.cc Thu Apr 23 09:35:16 2009 +0200
@@ -19,6 +19,7 @@
*/
#include "high-precision-128.h"
#include "ns3/test.h"
+#include "ns3/fatal-error.h"
#include <math.h>
#include <iostream>
@@ -151,10 +152,69 @@
{
EnsureSlow ();
const_cast<HighPrecision &> (o).EnsureSlow ();
- cairo_int128_t other = _cairo_int128_rsa (o.m_slowValue, 64);
- m_slowValue = _cairo_int128_mul (m_slowValue, other);
+ //use the 128 bits multiplication
+ m_slowValue = Mul128(m_slowValue,o.m_slowValue);
return false;
}
+/**
+ * this function multiplies two 128 bits fractions considering
+ * the high 64 bits as the integer part and the low 64 bits
+ * as the fractional part. It takes into account the sign
+ * of the operands to produce a signed 128 bits result.
+ */
+cairo_int128_t
+HighPrecision::Mul128(cairo_int128_t a, cairo_int128_t b )
+{
+ //Implement the 128 bits multiplication
+ cairo_int128_t result;
+ cairo_uint128_t hiPart,loPart,midPart;
+ bool resultNegative = false, signA = false,signB = false;
+
+ //take the sign of the operands
+ signA = _cairo_int128_negative (a);
+ signB = _cairo_int128_negative (b);
+ //the result is negative only if one of the operand is negative
+ if ((signA == true && signB == false) ||(signA == false && signB == true))
+ {
+ resultNegative = true;
+ }
+ //now take the absolute part to make sure that the resulting operands are positive
+ if (signA == true)
+ {
+ a = _cairo_int128_negate (a);
+ }
+ if (signB == true)
+ {
+ b = _cairo_int128_negate (b);
+ }
+
+ //Multiplying (a.h 2^64 + a.l) x (b.h 2^64 + b.l) =
+ // 2^128 a.h b.h + 2^64*(a.h b.l+b.h a.l) + a.l b.l
+ //get the low part a.l b.l
+ //multiply the fractional part
+ loPart = _cairo_uint64x64_128_mul (a.lo, b.lo);
+ //compute the middle part 2^64*(a.h b.l+b.h a.l)
+ midPart = _cairo_uint128_add(_cairo_uint64x64_128_mul(a.lo, b.hi),
+ _cairo_uint64x64_128_mul(a.hi, b.lo)) ;
+ //truncate the low part
+ result.lo = _cairo_uint64_add(loPart.hi,midPart.lo);
+ //compute the high part 2^128 a.h b.h
+ hiPart = _cairo_uint64x64_128_mul (a.hi, b.hi);
+ //truncate the high part and only use the low part
+ result.hi = _cairo_uint64_add(hiPart.lo,midPart.hi);
+ //if the high part is not zero, put a warning
+ if (hiPart.hi !=0)
+ {
+ NS_FATAL_ERROR("High precision 128 bits multiplication error: multiplication overflow.");
+ }
+ //add the sign to the result
+ if (resultNegative)
+ {
+ result = _cairo_int128_negate (result);
+ }
+ return result;
+}
+
bool
HighPrecision::Div (HighPrecision const &o)
{
@@ -351,6 +411,22 @@
a = HighPrecision (0.1);
a.Div (HighPrecision (1.25));
NS_TEST_ASSERT_EQUAL (a.GetDouble (), 0.08);
+ //test the multiplication
+ a = HighPrecision (0.5);
+ a.Mul(HighPrecision (5));
+ NS_TEST_ASSERT_EQUAL (a.GetDouble (), 2.5);
+ //test the sign of multiplication, first operand negative
+ a = HighPrecision (-0.5);
+ a.Mul(HighPrecision (5));
+ NS_TEST_ASSERT_EQUAL (a.GetDouble (), -2.5);
+ //two negative
+ a = HighPrecision (-0.5);
+ a.Mul(HighPrecision (-5));
+ NS_TEST_ASSERT_EQUAL (a.GetDouble (), 2.5);
+ //second operand negative
+ a = HighPrecision (0.5);
+ a.Mul(HighPrecision (-5));
+ NS_TEST_ASSERT_EQUAL (a.GetDouble (), -2.5);
return result;
--- a/src/simulator/high-precision-128.h Wed Apr 22 17:22:41 2009 +0200
+++ b/src/simulator/high-precision-128.h Thu Apr 23 09:35:16 2009 +0200
@@ -85,6 +85,7 @@
bool SlowSub (HighPrecision const &o);
bool SlowMul (HighPrecision const &o);
int SlowCompare (HighPrecision const &o) const;
+ cairo_uint128_t Mul128(cairo_uint128_t , cairo_uint128_t );
inline void EnsureSlow (void);
static const double MAX_64;
--- a/src/simulator/time.cc Wed Apr 22 17:22:41 2009 +0200
+++ b/src/simulator/time.cc Thu Apr 23 09:35:16 2009 +0200
@@ -572,11 +572,11 @@
Time t4;
t4 = Seconds (10.0) * Scalar (1.5);
- CheckTimeSec("old 11", t4.GetSeconds(), 10, ok);
+ CheckTimeSec("old 11", t4.GetSeconds(), 15, ok);
Time t5;
t5 = NanoSeconds (10) * Scalar (1.5);
- CheckTime("old 12", t5.GetNanoSeconds(), 10, ok);
+ CheckTime("old 12", t5.GetNanoSeconds(), 15, ok);
t4 = Seconds (10.0) * Scalar (15) / Scalar (10);
CheckTimeSec("old 13", t4.GetSeconds(), 15, ok);