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Further consolidates region map, now that shadowing is orthogonal.

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Thomas Harte 2021-02-28 15:22:36 -05:00
parent 496b6b5cfc
commit 2f45e07d82
1 changed files with 23 additions and 31 deletions
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54
Machines/Apple/AppleIIgs/MemoryMap.hpp
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@ -64,27 +64,16 @@ class MemoryMap {
// Current beliefs about the IIgs memory map:
//
// * language card banking applies to banks $00, $01, $e0 and $e1;
// * auxiliary memory switches apply to bank $e0 only, but thereby also affect shadowed writes from $00;
// * auxiliary memory switches apply to bank $00 only;
// * shadowing may be enabled only on banks $00 and $01, or on all RAM pages; and
// * whether bit 16 of the address is passed to the Mega II is selectable — this affects both the destination
// of odd-bank shadows, and whether bank $e1 is actually distinct from $e0.
//
// So:
//
// * banks $00 and $01 need to be divided both by shadowing zones and by the language card;
// * all other fast RAM banks need be divided by shadowing zone only;
// * $e0 needs to be ready for any language/auxiliary arrangement;
// * $e1 needs to apply the language card mapping only; and
// * ROM banks don't need to be divided? Or probably they shadow writes back to $e0/$e1 too?
// Shadowing zones:
//
// $0400–$0800 Text Page 1
// $0800–$0C00 Text Page 2 [ROM 03 machines]
// $2000–$4000 High-res Page 1, and Super High-res in odd banks
// $4000–$6000 High-res Page 2, and Huper High-res in odd banks
// $6000–$a000 Odd banks only, rest of Super High-res
// [plus IO and language card space, subject to your definition of shadowing]
// * bank $00 needs to be divided by auxiliary and language card zones;
// * banks $01, $e0 and $e1 need to be divided by language card zones only; and
// * ROM banks and all other fast RAM banks don't need subdivision.
// Language card zones:
//
@ -111,20 +100,17 @@ class MemoryMap {
region();
// Bank $00: all locations potentially affected by the auxiliary switches or the
// language switches. Which will naturally align with shadowable zones.
// language switches.
set_regions(0x00, {
0x0200, 0x0400, 0x0800, 0x0c00,
0x2000, 0x4000, 0x6000,
0x0200, 0x0400, 0x0800,
0x2000, 0x4000,
0xc000, 0xc100, 0xc300, 0xc400, 0xc800,
0xd000, 0xe000,
0xffff
});
// Bank $01: all locations potentially affected by the language switches, by shadowing,
// or marked for IO.
// Bank $01: all locations potentially affected by the language switches and card switches.
set_regions(0x01, {
0x0400, 0x0800, 0x0c00,
0x2000, 0x4000, 0x6000, 0xa000,
0xc000, 0xc100, 0xc300, 0xc400, 0xc800,
0xd000, 0xe000,
0xffff
@ -428,6 +414,15 @@ class MemoryMap {
// The interpretations of how the overlapping high-res and super high-res inhibit
// bits apply used below is taken from The Apple IIgs Technical Reference, P. 178.
// Of course, zones are:
//
// $0400–$0800 Text Page 1
// $0800–$0C00 Text Page 2 [ROM 03 machines]
// $2000–$4000 High-res Page 1, and Super High-res in odd banks
// $4000–$6000 High-res Page 2, and Huper High-res in odd banks
// $6000–$a000 Odd banks only, rest of Super High-res
// [plus IO and language card space, subject to your definition of shadowing]
constexpr int shadow_shift = 10;
constexpr int auxiliary_offset = 0x10000 >> shadow_shift;
@ -492,9 +487,7 @@ class MemoryMap {
// Base: $0800–$1FFF.
set(0x08, state.base);
set(0x0c, state.base);
assert_is_region(0x08, 0x0c);
assert_is_region(0x0c, 0x20);
assert_is_region(0x08, 0x20);
// Region $2000–$3FFF.
set(0x20, state.region_20_40);
@ -502,9 +495,7 @@ class MemoryMap {
// Base: $4000–$BFFF.
set(0x40, state.base);
set(0x60, state.base);
assert_is_region(0x40, 0x60);
assert_is_region(0x60, 0xc0);
assert_is_region(0x40, 0xc0);
#undef set
@ -562,9 +553,6 @@ class MemoryMap {
IsIO = 1 << 1, // Indicates that this region should be checked for soft switches, registers, etc.
};
};
std::array<Region, 64> regions; // The assert above ensures that this is large enough; there's no
// doctrinal reason for it to be whatever size it is now, just
// adjust as required.
// Shadow_pages: divides the final 128kb of memory into 1kb chunks and includes a flag to indicate whether
// each is a potential destination for shadowing.
@ -572,6 +560,10 @@ class MemoryMap {
// Shadow_banks: divides the whole 16mb of memory into 128kb chunks and includes a flag to indicate whether
// each is a potential source of shadowing.
std::bitset<128> shadow_pages, shadow_banks;
std::array<Region, 40> regions; // An assert above ensures that this is large enough; there's no
// doctrinal reason for it to be whatever size it is now, just
// adjust as required.
};
// TODO: branching below on region.read/write is predicated on the idea that extra scratch space