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Rewrote the x86 64-bit division stubs, which now actually work.

This commit is contained in:
Jonas 'Sortie' Termansen 2011-12-04 19:02:35 +01:00
parent a2dd8be7aa
commit de70b1804d
1 changed files with 37 additions and 56 deletions
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93
libmaxsi/c++.cpp
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@ -31,76 +31,57 @@ extern "C" void __cxa_pure_virtual()
#ifdef PLATFORM_X86
// TODO: These two stubs are buggy!
// Divides two 64-bit integers in O(logN). I think.
extern "C" uint64_t __udivdi3(uint64_t A, uint64_t B)
extern "C" uint64_t __udivdi3(uint64_t a, uint64_t b)
{
uint64_t ACC = 0;
uint64_t R = 0;
uint64_t PWR = 1;
uint64_t EXP = B;
while ( EXP <= A - ACC )
uint64_t result = 0;
uint64_t power = 1;
uint64_t remainder = a;
uint64_t divisor = b;
while ( divisor * 2 <= remainder )
{
R += PWR;
ACC += EXP;
if ( 2 * EXP <= A - ACC )
power *= 2;
divisor *= 2;
}
while ( divisor <= remainder )
{
remainder -= divisor;
result += power;
while ( power > 1 && remainder < divisor )
{
PWR++;
EXP *= 2;
}
else if ( A - ACC < B )
{
break;
}
else
{
while ( A - ACC < EXP )
{
PWR--;
EXP /= 2;
}
divisor /= 2;
power /= 2;
}
}
return R;
return result;
}
// Mods two 64-bit integers in O(logN). I think.
extern "C" uint64_t __umoddi3(uint64_t A, uint64_t B)
extern "C" uint64_t __umoddi3(uint64_t a, uint64_t b)
{
uint64_t ACC = 0;
uint64_t R = 0;
uint64_t PWR = 1;
uint64_t EXP = B;
while ( EXP <= A - ACC )
uint64_t result = 0;
uint64_t power = 1;
uint64_t remainder = a;
uint64_t divisor = b;
while ( divisor * 2 <= remainder )
{
R += PWR;
ACC += EXP;
if ( 2 * EXP <= A - ACC )
power *= 2;
divisor *= 2;
}
while ( divisor <= remainder )
{
remainder -= divisor;
result += power;
while ( power > 1 && remainder < divisor )
{
PWR++;
EXP *= 2;
}
else if ( A - ACC < B )
{
break;
}
else
{
while ( A - ACC < EXP )
{
PWR--;
EXP /= 2;
}
divisor /= 2;
power /= 2;
}
}
return A - ACC;
return remainder;
}
#endif