Howdy,
I stumbled across a tiny NES emulator written in C++
(http://bisqwit.iki.fi/jutut/kuvat/programming_examples/nesemu1/nesemu1.cc)
that I feel compelled to make even tinier with some D magic. I am
having trouble with a nested template in the code.
The C++ code:
// Bitfield utilities
template<unsigned bitno, unsigned nbits=1, typename T=u8>
struct RegBit
{
T data;
enum { mask = (1u << nbits) - 1u };
template<typename T2>
RegBit& operator=(T2 val)
{
data = (data & ~(mask << bitno)) | ((nbits > 1 ? val &
mask : !!val) << bitno);
return *this;
}
operator unsigned() const { return (data >> bitno) & mask; }
RegBit& operator++ () { return *this = *this + 1; }
unsigned operator++ (int) { unsigned r = *this; ++*this;
return r; }
};
My D implementation thus far:
// To avoid type confusion...
alias u8 = uint_least8_t;
alias u32 = uint_least32_t;
template RegBit(uint bitno, uint nbits = 1, T = u8) {
T data;
enum { mask = (1u << nbits) - 1u }
// FIXME: Nested template frustration here... HELP
void opAssign(T2 val)
{
data = (data & ~(mask << bitno)) | ((nbits > 1 ? val &
mask : !!val) << bitno);
return *this;
}
auto opCall() { return (data >> bitno) & mask; }
ref RegBit opUnary(string s)() if (s == "++") { return *this
= *this + 1; }
ref RegBit opUnary(string s)(int) if (s== "++") { uint r =
*this; ++*this; return r; }
}
Any push in the right direction would be greatly appreciated. I'm
just trying to get a D implementation up and running before I
start making this smaller and more intuitive.
