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Rotate command-engine addresses in modes 6 and 7.

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This commit is contained in:
Thomas Harte 2023-03-03 23:06:52 -05:00
parent 0ea1da10d6
commit e58a488add
1 changed files with 9 additions and 5 deletions
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14
Components/9918/Implementation/9918Base.hpp
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@ -266,6 +266,10 @@ template <Personality personality> struct Base: public Storage<personality> {
return ScreenMode::Blank;
}
static AddressT rotate(AddressT address) {
return AddressT((address >> 1) | (address << 16)) & memory_mask(personality);
}
AddressT command_address(Vector location) const {
if constexpr (is_yamaha_vdp(personality)) {
switch(this->screen_mode_) {
@ -283,16 +287,16 @@ template <Personality personality> struct Base: public Storage<personality> {
);
case ScreenMode::YamahaGraphics6: // 512 pixels @ 4bpp
return AddressT(
return rotate(AddressT(
(location.v[0] >> 1) +
(location.v[1] << 8)
);
));
case ScreenMode::YamahaGraphics7: // 256 pixels @ 8bpp
return AddressT(
return rotate(AddressT(
(location.v[0] >> 0) +
(location.v[1] << 8)
);
));
}
} else {
return 0;
@ -459,7 +463,7 @@ template <Personality personality> struct Base: public Storage<personality> {
// Rotate address one to the right as the hardware accesses
// the underlying banks of memory alternately but presents
// them as if linear.
address = (address >> 1) | (address << 16);
address = rotate(address);
}
// Also check whether expansion RAM is the true target here.