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Add sideways ROM paging.

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This commit is contained in:
Thomas Harte
2025-09-15 22:26:02 -04:00
parent e8a16a8fce
commit f499de3622
1 changed files with 13 additions and 1 deletions
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14
Machines/Acorn/BBCMicro/BBCMicro.cpp
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@@ -229,6 +229,12 @@ public:
} else {
user_via_.write(address, *value);
}
} else if(address == 0xfe30) {
if(is_read(operation)) {
*value = 0xfe;
} else {
page_sideways(*value & 0xf);
}
} else {
Logger::error().append("Unhandled IO access at %04x", address);
}
@@ -239,7 +245,12 @@ public:
// ROM or RAM access.
//
if(is_read(operation)) {
*value = memory_[address >> 14][address];
// TODO: probably don't do this with this condition? See how it compiles. If it's a CMOV somehow, no problem.
if((address >> 14) == 2 && !sideways_read_mask_) {
*value = 0xff;
} else {
*value = memory_[address >> 14][address];
}
} else {
if(memory_write_masks_[address >> 14]) {
memory_[address >> 14][address] = *value;
@@ -304,6 +315,7 @@ private:
void install_sideways(const size_t slot, const std::vector<uint8_t> &source, bool is_writeable) {
rom_write_masks_[slot] = is_writeable;
rom_inserted_[slot] = true;
assert(source.size() == roms_[slot].size());
std::copy(source.begin(), source.end(), roms_[slot].begin());