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Switch to a default 1mb of Chip RAM.

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This commit is contained in:
Thomas Harte 2021-11-29 16:55:45 -05:00
parent 8584ee609f
commit cd0148e0bc
1 changed files with 20 additions and 16 deletions
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36
Machines/Amiga/MemoryMap.hpp
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@ -11,9 +11,15 @@
namespace Amiga { namespace Amiga {
struct MemoryMap { class MemoryMap {
private:
static constexpr auto PermitRead = CPU::MC68000::Microcycle::PermitRead;
static constexpr auto PermitWrite = CPU::MC68000::Microcycle::PermitWrite;
static constexpr auto PermitReadWrite = PermitRead | PermitWrite;
public: public:
std::array<uint8_t, 512*1024> chip_ram{}; // TODO: decide what of the below I want to be dynamic.
std::array<uint8_t, 1024*1024> chip_ram{};
std::array<uint8_t, 512*1024> kickstart{0xff}; std::array<uint8_t, 512*1024> kickstart{0xff};
struct MemoryRegion { struct MemoryRegion {
@ -26,7 +32,8 @@ struct MemoryMap {
// //
// 00'0000 – 08'0000: chip RAM. [or overlayed KickStart] // 00'0000 – 08'0000: chip RAM. [or overlayed KickStart]
// – 10'0000: extended chip ram for ECS. // – 10'0000: extended chip ram for ECS.
// – 20'0000: auto-config space (/fast RAM). // – 20'0000: slow RAM and further chip RAM.
// – a0'0000: auto-config space (/fast RAM).
// ... // ...
// bf'd000 – c0'0000: 8250s. // bf'd000 – c0'0000: 8250s.
// c0'0000 – d8'0000: pseudo-fast RAM. // c0'0000 – d8'0000: pseudo-fast RAM.
@ -37,7 +44,7 @@ struct MemoryMap {
// f0'0000 — : 512kb Kickstart (or possibly just an extra 512kb reserved for hypothetical 1mb Kickstart?). // f0'0000 — : 512kb Kickstart (or possibly just an extra 512kb reserved for hypothetical 1mb Kickstart?).
// f8'0000 — : 256kb Kickstart if 2.04 or higher. // f8'0000 — : 256kb Kickstart if 2.04 or higher.
// fc'0000 – : 256kb Kickstart otherwise. // fc'0000 – : 256kb Kickstart otherwise.
set_region(0xfc'0000, 0x1'00'0000, kickstart.data(), CPU::MC68000::Microcycle::PermitRead); set_region(0xfc'0000, 0x1'00'0000, kickstart.data(), PermitRead);
reset(); reset();
} }
@ -51,26 +58,23 @@ struct MemoryMap {
} }
overlay_ = enabled; overlay_ = enabled;
set_region(0x00'0000, uint32_t(chip_ram.size()), chip_ram.data(), PermitReadWrite);
if(enabled) { if(enabled) {
set_region(0x00'0000, 0x08'0000, kickstart.data(), CPU::MC68000::Microcycle::PermitRead); set_region(0x00'0000, 0x08'0000, kickstart.data(), PermitRead);
} else {
// Mirror RAM to fill out the address range up to $20'0000.
set_region(0x00'0000, 0x08'0000, chip_ram.data(), CPU::MC68000::Microcycle::PermitRead | CPU::MC68000::Microcycle::PermitWrite);
set_region(0x08'0000, 0x10'0000, chip_ram.data(), CPU::MC68000::Microcycle::PermitRead | CPU::MC68000::Microcycle::PermitWrite);
set_region(0x10'0000, 0x18'0000, chip_ram.data(), CPU::MC68000::Microcycle::PermitRead | CPU::MC68000::Microcycle::PermitWrite);
set_region(0x18'0000, 0x20'0000, chip_ram.data(), CPU::MC68000::Microcycle::PermitRead | CPU::MC68000::Microcycle::PermitWrite);
} }
} }
private: private:
bool overlay_ = false; bool overlay_ = false;
void set_region(int start, int end, uint8_t *base, unsigned int read_write_mask) { void set_region(uint32_t start, uint32_t end, uint8_t *base, unsigned int read_write_mask) {
assert(!(start & ~0xfc'0000)); [[maybe_unused]] constexpr uint32_t precision_loss_mask = uint32_t(~0xfc'0000);
assert(!((end - (1 << 18)) & ~0xfc'0000)); assert(!(start & precision_loss_mask));
assert(!((end - (1 << 18)) & precision_loss_mask));
assert(end > start);
base -= start; if(base) base -= start;
for(int c = start >> 18; c < end >> 18; c++) { for(decltype(start) c = start >> 18; c < end >> 18; c++) {
regions[c].contents = base; regions[c].contents = base;
regions[c].read_write_mask = read_write_mask; regions[c].read_write_mask = read_write_mask;
} }