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Eliminate hot-path switch.

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This commit is contained in:
Thomas Harte 2024-04-17 21:36:39 -04:00
parent b63178132d
commit 30c2c65b77
1 changed files with 24 additions and 22 deletions
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46
Machines/Acorn/Archimedes/MemoryController.hpp
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@ -107,6 +107,25 @@ struct MemoryController {
high_rom_access_time_ = ROMAccessTime((address >> 6) & 3);
low_rom_access_time_ = ROMAccessTime((address >> 4) & 3);
page_size_ = PageSize((address >> 2) & 3);
switch(page_size_) {
default:
case PageSize::kb4:
page_address_shift_ = 12;
page_adddress_mask_ = 0x0fff;
break;
case PageSize::kb8:
page_address_shift_ = 13;
page_adddress_mask_ = 0x1fff;
break;
case PageSize::kb16:
page_address_shift_ = 14;
page_adddress_mask_ = 0x3fff;
break;
case PageSize::kb32:
page_address_shift_ = 15;
page_adddress_mask_ = 0x7fff;
break;
}
logger.info().append("MEMC Control: %08x -> OS:%d sound:%d video:%d refresh:%d high:%d low:%d size:%d", address, os_mode_, sound_dma_enable_, video_dma_enable_, dynamic_ram_refresh_, high_rom_access_time_, low_rom_access_time_, page_size_);
map_dirty_ = true;
@ -296,6 +315,8 @@ struct MemoryController {
kb16 = 0b10,
kb32 = 0b11,
} page_size_ = PageSize::kb4;
int page_address_shift_ = 12;
uint32_t page_adddress_mask_ = 0xffff;
// Address translator.
//
@ -337,33 +358,14 @@ struct MemoryController {
}
address = aligned<IntT>(address);
address &= 0x1ff'ffff;
size_t page;
// TODO: eliminate switch here.
switch(page_size_) {
default:
case PageSize::kb4:
page = address >> 12;
address &= 0x0fff;
break;
case PageSize::kb8:
page = address >> 13;
address &= 0x1fff;
break;
case PageSize::kb16:
page = address >> 14;
address &= 0x3fff;
break;
case PageSize::kb32:
page = address >> 15;
address &= 0x7fff;
break;
}
const size_t page = address >> page_address_shift_;
const auto &map = mapping<is_read>(trans, os_mode_);
if(!map[page]) {
return nullptr;
}
address &= page_adddress_mask_;
return reinterpret_cast<IntT *>(&map[page][address]);
}