mirror of
https://github.com/libretro/bsnes-libretro.git
synced 2024-11-26 18:40:47 +00:00
d87a0f633d
byuu says:
- bsnes: added video filters from bsnes v082
- bsnes: added ZSNES snow effect option when games paused or unloaded
(no, I'm not joking)
- bsnes: added 7-zip support (LZMA 19.00 SDK)
[Recent higan WIPs have also mentioned bsnes changes, although the higan code
no longer includes the bsnes code. These changes include:
- higan, bsnes: added EXLOROM, EXLOROM-RAM, EXHIROM mappings
- higan, bsnes: focus the viewport after leaving fullscreen exclusive
mode
- bsnes: re-added mightymo's cheat code database
- bsnes: improved make install rules for the game and cheat code
databases
- bsnes: delayed construction of hiro::Window objects to properly show
bsnes window icons
- Ed.]
71 lines
2.0 KiB
C++
71 lines
2.0 KiB
C++
#pragma once
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//table-driven galois field modulo 2
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//do not use with GF(2^17) or larger
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namespace nall {
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template<typename field, uint Elements, uint Polynomial>
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struct GaloisField {
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using type = GaloisField;
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GaloisField(uint x = 0) : x(x) {}
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operator field() const { return x; }
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auto operator^(field y) const -> type { return x ^ y; }
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auto operator+(field y) const -> type { return x ^ y; }
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auto operator-(field y) const -> type { return x ^ y; }
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auto operator*(field y) const -> type { return x && y ? exp(log(x) + log(y)) : 0; }
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auto operator/(field y) const -> type { return x && y ? exp(log(x) + Elements - log(y)) : 0; }
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auto& operator =(field y) { return x = y, *this; }
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auto& operator^=(field y) { return x = operator^(y), *this; }
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auto& operator+=(field y) { return x = operator^(y), *this; }
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auto& operator-=(field y) { return x = operator^(y), *this; }
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auto& operator*=(field y) { return x = operator*(y), *this; }
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auto& operator/=(field y) { return x = operator/(y), *this; }
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auto pow(field y) const -> type { return exp(log(x) * y); }
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auto inv() const -> type { return exp(Elements - log(x)); } // 1/x
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static auto log(uint x) -> uint {
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enum : uint { Size = bit::round(Elements), Mask = Size - 1 };
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static array<field[Size]> log = [] {
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uint shift = 0, polynomial = Polynomial;
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while(polynomial >>= 1) shift++;
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shift--;
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array<field[Size]> log;
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field x = 1;
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for(uint n : range(Elements)) {
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log[x] = n;
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x = x << 1 ^ (x >> shift ? Polynomial : 0);
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}
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log[0] = 0; //-inf (undefined)
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return log;
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}();
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return log[x & Mask];
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}
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static auto exp(uint x) -> uint {
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static array<field[Elements]> exp = [] {
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uint shift = 0, polynomial = Polynomial;
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while(polynomial >>= 1) shift++;
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shift--;
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array<field[Elements]> exp;
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field x = 1;
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for(uint n : range(Elements)) {
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exp[n] = x;
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x = x << 1 ^ (x >> shift ? Polynomial : 0);
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}
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return exp;
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}();
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return exp[x % Elements];
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}
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field x;
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};
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}
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