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fix fixed point math

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This commit is contained in:
Daniel Larimer 2014-10-15 20:46:24 -04:00
parent 2b76b6d5fe
commit ec9e85d268
3 changed files with 36 additions and 10 deletions
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6
include/fc/real128.hpp
View file

@ -10,8 +10,8 @@ namespace fc {
class real128 class real128
{ {
public: public:
real128( uint64_t integer = 0):fixed(integer,0){} real128( uint64_t integer = 0);
real128( const std::string& str ); explicit real128( const std::string& str );
operator std::string()const; operator std::string()const;
friend real128 operator * ( real128 a, const real128& b ) { a *= b; return a; } friend real128 operator * ( real128 a, const real128& b ) { a *= b; return a; }
@ -24,7 +24,7 @@ namespace fc {
real128& operator /= ( const real128& o ); real128& operator /= ( const real128& o );
real128& operator *= ( const real128& o ); real128& operator *= ( const real128& o );
uint64_t to_uint64()const{ return fixed.high_bits(); } uint64_t to_uint64()const;
private: private:
uint128 fixed; uint128 fixed;

24
src/real128.cpp
View file

@ -3,8 +3,19 @@
#include <fc/exception/exception.hpp> #include <fc/exception/exception.hpp>
#include <sstream> #include <sstream>
#define PRECISION (1000000ll * 1000000ll * 1000000ll)
namespace fc namespace fc
{ {
uint64_t real128::to_uint64()const
{
return (fixed/PRECISION).to_uint64();
}
real128::real128( uint64_t integer )
{
fixed = uint128(integer) * PRECISION;
}
real128& real128::operator += ( const real128& o ) real128& real128::operator += ( const real128& o )
{ {
fixed += o.fixed; fixed += o.fixed;
@ -22,7 +33,7 @@ namespace fc
fc::bigint self(fixed); fc::bigint self(fixed);
fc::bigint other(o.fixed); fc::bigint other(o.fixed);
self *= fc::bigint(uint128(0,-1)); self *= PRECISION;
self /= other; self /= other;
fixed = self; fixed = self;
@ -34,7 +45,7 @@ namespace fc
fc::bigint self(fixed); fc::bigint self(fixed);
fc::bigint other(o.fixed); fc::bigint other(o.fixed);
self *= other; self *= other;
self /= fc::bigint(uint128(0,-1)); self /= PRECISION;
fixed = self; fixed = self;
return *this; return *this;
} FC_CAPTURE_AND_RETHROW( (*this)(o) ) } } FC_CAPTURE_AND_RETHROW( (*this)(o) ) }
@ -55,7 +66,7 @@ namespace fc
++c; ++c;
digit = *c - '0'; digit = *c - '0';
} }
fixed = fc::uint128(int_part, 0); *this = real128(int_part);
} }
else else
{ {
@ -90,11 +101,10 @@ namespace fc
real128::operator std::string()const real128::operator std::string()const
{ {
std::stringstream ss; std::stringstream ss;
ss << to_uint64(); ss << std::string(fixed / PRECISION);
ss << '.'; ss << '.';
real128 frac(fixed.low_bits()); auto frac = (fixed % PRECISION) + PRECISION;
ss << std::string( frac ).substr(1);
ss << std::string( frac.fixed ).substr(1);
auto number = ss.str(); auto number = ss.str();
while( number.back() == '0' ) number.pop_back(); while( number.back() == '0' ) number.pop_back();

16
tests/real128_test.cpp
View file

@ -1,6 +1,7 @@
#include <fc/real128.hpp> #include <fc/real128.hpp>
#define BOOST_TEST_MODULE Real128Test #define BOOST_TEST_MODULE Real128Test
#include <boost/test/unit_test.hpp> #include <boost/test/unit_test.hpp>
#include <fc/log/logger.hpp>
using fc::real128; using fc::real128;
using std::string; using std::string;
@ -16,7 +17,22 @@ BOOST_AUTO_TEST_CASE(real128_test)
BOOST_CHECK_EQUAL(string(real128(12345)), string("12345.")); BOOST_CHECK_EQUAL(string(real128(12345)), string("12345."));
BOOST_CHECK_EQUAL(string(real128(0)), string(real128("0"))); BOOST_CHECK_EQUAL(string(real128(0)), string(real128("0")));
real128 ten(10);
real128 two(2);
real128 twenty(20);
BOOST_CHECK_EQUAL( string(ten), "10." );
BOOST_CHECK_EQUAL( string(two), "2." );
BOOST_CHECK_EQUAL( string(ten+two), "12." );
BOOST_CHECK_EQUAL( string(ten-two), "8." );
BOOST_CHECK_EQUAL( string(ten*two), "20." );
BOOST_CHECK_EQUAL( string(ten/two), "5." );
BOOST_CHECK_EQUAL(real128("12345.6789").to_uint64(), 12345); BOOST_CHECK_EQUAL(real128("12345.6789").to_uint64(), 12345);
BOOST_CHECK_EQUAL((real128("12345.6789")*10000).to_uint64(), 123456789); BOOST_CHECK_EQUAL((real128("12345.6789")*10000).to_uint64(), 123456789);
BOOST_CHECK_EQUAL(string(real128("12345.6789")), string("12345.6789")); BOOST_CHECK_EQUAL(string(real128("12345.6789")), string("12345.6789"));
wdump( (ten)(two)(twenty) );
wdump( (real128(uint64_t(-1)))(uint64_t(-1)) );
wdump((real128("12345.6789")) );
} }