mirror of https://github.com/bsnes-emu/bsnes.git
59 lines
1.5 KiB
C++
59 lines
1.5 KiB
C++
auto V30MZ::read(Size size, uint16 segment, uint16 address) -> uint16 {
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uint16 data = read(segment * 16 + address);
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if(size == Word) data |= read(segment * 16 + ++address) << 8;
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return data;
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}
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auto V30MZ::write(Size size, uint16 segment, uint16 address, uint16 data) -> void {
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write(segment * 16 + address, data);
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if(size == Word) write(segment * 16 + ++address, data >> 8);
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}
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//
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auto V30MZ::readIP(Size size) -> uint16 {
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uint16 data = read(size, r.cs, r.ip);
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return r.ip += size, data;
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}
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//
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auto V30MZ::readSP() -> uint16 {
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uint16 data = read(Word, r.ss, r.sp);
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return r.sp += Word, data;
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}
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auto V30MZ::writeSP(uint16 data) -> void {
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r.sp -= Word;
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write(Word, r.ss, r.sp, data);
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}
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//
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auto V30MZ::readModRM(uint8 modRM) -> uint32 {
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if((modRM & 0xc7) == 0x06) return r.ds << 16 | readIP(Word);
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uint16 s = 0, a = 0;
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if((modRM & 0xc0) == 0x40) a = (int8)readIP(Byte);
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if((modRM & 0xc0) == 0x80) a = (int16)readIP(Word);
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switch(modRM & 7) {
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case 0: s = r.ds; a += r.bx + r.si; break;
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case 1: s = r.ds; a += r.bx + r.di; break;
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case 2: s = r.ss; a += r.bp + r.si; break;
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case 3: s = r.ss; a += r.bp + r.di; break;
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case 4: s = r.ds; a += r.si; break;
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case 5: s = r.ds; a += r.di; break;
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case 6: s = r.ss; a += r.bp; break;
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case 7: s = r.ds; a += r.bx; break;
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}
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return s << 16 | a;
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}
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auto V30MZ::readModRM(Size size, uint8 modRM) -> uint16 {
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if(modRM >= 0xc0) return getRegister(size, modRM);
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auto addr = readModRM(modRM);
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return read(size, addr >> 16, addr);
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}
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