more normalization and commenting

This commit is contained in:
Jorj Bauer 2021-01-08 19:25:08 -05:00
parent fe46c4ab52
commit 0468bf43c5
2 changed files with 218 additions and 27 deletions

View File

@ -61,8 +61,15 @@ Current write page table [512 bytes] in real ram
*/
// This has a split memory model so more often addressed pages can be
// in internal memory, and an external memory can hold others.
// All the pages. Because we don't have enough RAM for both the
// display's DMA and the Apple's 148k (128k + ROM space), we're using
// an external SRAM for some of this. Anything that's accessed very
// often should be in the *low* pages, b/c those are in internal
// Teensy RAM. When we run out of preallocated RAM (cf. vmram.h), we
// fall over to an external 256kB SRAM (which is much slower).
//
// Zero page (and its alts) are the most used pages (the stack is in
// page 1).
//
// We want the video display pages in real RAM as much as possible,
// since blits wind up touching so much of it. If we can keep that in
@ -79,20 +86,19 @@ enum {
MP_ZP = 0, // page 0/1 * 2 page variants = 4; 0..3
MP_4 = 4, // 0x04 - 0x07 (text display pages) * 2 variants = 8; 4..11
MP_20 = 12, // 0x20 - 0x5F * 2 variants = 128; 12..139
// Pages that can go to external RAM if needed:
// Pages that can go to external SRAM:
MP_2 = 140, // 0x02 - 0x03 * 2 variants = 4; 140..143
MP_8 = 144, // 0x08 - 0x1F * 2 = 48; 144..191
MP_60 = 192, // 0x60 - 0xBF * 2 = 192; 192..383
MP_C1 = 384, // start of 0xC1-0xCF * 2 page variants = 30; 384-413
MP_C8 = 398, // 0xc8 - 0xcf, 3 page variants = 24; 398 - 421
MP_C1 = 384, // start of 0xC1-0xC7 * 2 page variants = 14; 384-397
MP_C8 = 398, // 0xc8 - 0xcf, 3 page variants = 24; 398 - 421
MP_D0 = 422, // start of 0xD0-0xDF * 5 page variants = 80; 422 - 501
MP_E0 = 502, // start of 0xE0-0xFF * 3 page variants = 96; 502 - 597
MP_C0 = 598
MP_C0 = 598
// = 599 pages in all (149.75k)
};
static uint16_t _pageNumberForRam(uint8_t highByte, uint8_t variant)
{
if (highByte <= 1) {
@ -118,14 +124,13 @@ static uint16_t _pageNumberForRam(uint8_t highByte, uint8_t variant)
return MP_C0;
}
if (highByte <= 0xC7) {
// 0xC1 - 0xC7
// 0xC1-0xC7
return ((highByte - 0xC1) * 2 + variant + MP_C1);
}
if (highByte <= 0xCF) {
// bank-switched ROM. 0 = built-in; 1 = 80-column (slot 3); 2 = mouse (slot 4)
return ((highByte - 0xC8) * 3 + variant + MP_C8);
}
if (highByte <= 0xDF) {
// 0xD0 - 0xDF 16 * 5 pages = 80 pages (20k)
return ((highByte - 0xD0) * 5 + variant + MP_D0);
@ -229,6 +234,8 @@ bool AppleMMU::Deserialize(int8_t fd)
return true;
}
void AppleMMU::Reset()
{
resetRAM();
@ -925,6 +932,7 @@ void AppleMMU::resetRAM()
for (uint16_t i=0x80; i<=0xFF; i++) {
uint16_t page0 = _pageNumberForRam(i, 0);
uint16_t page1 = _pageNumberForRam(i, 1);
for (uint16_t k=0; k<0x100; k++) {
uint16_t idx = ((i-0x80) << 8) | k;
#ifdef TEENSYDUINO
@ -932,28 +940,30 @@ void AppleMMU::resetRAM()
#else
uint8_t v = romData[idx];
#endif
// The space from 0xC1 through 0xCF is ROM image territory. We
// load the C3 ROM in to page 0, but not in page 1; and then we
// load C800.CFFF to both the main ROM (page 0) and the C3 aux ROM
// The space from 0xc1 through 0xcf is ROM image territory. We
// load the C3 ROM in to page 0, but not page 1; and then we
// load c800.CFFF to both main ROM (page 0) and the C3 aux ROM
// (page 1) to convince the VM that we've got 128k of RAM and an
// 80-column card.
if (i >= 0xc1 && i <= 0xcf) {
if (i == 0xc3) {
// C300..C3FF => built-in ROM
g_ram.writeByte((page0 << 8) | (k & 0xFF), v);
} else if (i >= 0xc8) {
// C800..CFFF => built-in ROM and slot 3 extended ROM
if (i >= 0xc1 && i <= 0xcf) {
g_ram.writeByte((page0 << 8) | (k & 0xFF), v);
g_ram.writeByte((page1 << 8) | (k & 0xFF), v);
} else {
// C000..C2FF and C400..C7FF are main ROM
g_ram.writeByte((page1 << 8) | (k & 0xFF), v);
}
} else {
// Everything else goes in page 0.
g_ram.writeByte((page0 << 8) | (k & 0xFF), v);
}
else if (i >= 0xc8) {
// C800..CFFF => built-in ROM and slot 3 extended ROM
g_ram.writeByte((page0 << 8) | (k & 0xFF), v);
g_ram.writeByte((page1 << 8) | (k & 0xFF), v);
}
else {
// C000..C2FF and C400..c7FF are main ROM
g_ram.writeByte((page1 << 8) | (k & 0xFF), v);
}
} else {
// Everything else goes in page 0.
g_ram.writeByte((page0 << 8) | (k & 0xFF), v);
}
}
}
@ -1088,14 +1098,14 @@ void AppleMMU::updateMemoryPages()
// for a given peripheral to C800..CFFF.
if (slotLatch != -1) {
// FIXME: this is a hacky mess. Slot 3 (the 80-col card) is
// supported as "page 1"; and Slot 4 (the mouse card) is
// supported as "page 2".
// supported, as page "1"; and Slot 4 (the mouse card) is
// supported as page "2".
if (slotLatch == 3) {
for (int i=0xc8; i <= 0xcf; i++) {
readPages[i] = _pageNumberForRam(i, 1);
}
} else if (slotLatch == 4) {
for (int i=0xc8; i<=0xcf; i++) {
for (int i=0xc8; i <= 0xcf; i++) {
readPages[i] = _pageNumberForRam(i, 2);
}
}

View File

@ -36,6 +36,187 @@ void Mouse::writeSwitches(uint8_t s, uint8_t v)
void Mouse::loadROM(uint8_t *toWhere)
{
/* ROM Disassembly:
C400- 2C 58 FF BIT $FF58 ; test bits in FF58 w/ A
C403- 70 1B BVS $C420 ; V will contain bit 6 from $FF58, which should be $20 on boot-up
C405- 38 SEC
C406- 90 18 BCC $C420 ; no-op; unless called @ $C406 directly?
C408- B8 CLV ; clear overflow
C409- 50 15 BVC $C420 ; always branches
; unused... ? more lookup table... ?
C40B- 01 20 ORA ($20,X)
C40D- AE AE AE LDX $AEAE
; This is the lookup table for entry addresses
C410- AE
C411- 00
C412- 6D ;(setmouse @ c46d)
C413- 75 ;(servemouse @ C475)
C414- 8E ;(readmouse @ C48E)
C415- 9F ;(clearmouse @ C49F)
C416- A4 ;(posmouse @ C4A4)
C417- 86 ;(clampmouse @ C486)
C418- A9 ;(homemouse @ C4A9)
C419- 97 ;(initmouse @ C497)
C41A- AE
C41B- AE
C41C- AE ;(semi-documented: sets mouse frequency handler to 60 or 50 hz)
C41D- AE
C41E- AE
C41F- AE
; Main
C420- 48 PHA ; push accumulator to stack
C421- 98 TYA
C422- 48 PHA ; push Y to stack
C423- 8A TXA
C424- 48 PHA ; push X to stack
C424- 48 PHA
C425- 08 PHP ; push status to stack
C426- 78 SEI ; disable interrupts
; This JSR $FF58 is a trick to get the address we're calling from. By
; default, $FF58 contains a RTS (until patched as the DOS '&' vector,
; or ProDOS does something similar). As long as this executes before
; the DOS takes over, it's safe; but if we're doing this after ProDOS
; loads, a 64k machine might have garbage after the language card RAM
; is loaded here. A safer alternative would be something like
; LDA #$60 ; Write an RTS ($60) to a temporary memory
; STA WORK ; address, and then
; JSR WORK ; jump to it
; TSX
; LDA $100, X ; grab the return address off the stack
C427- 20 58 FF JSR $FF58
C42A- BA TSX
C42B- BD 00 01 LDA $0100,X
C42E- AA TAX
C42F- 0A ASL
C430- 0A ASL
C431- 0A ASL
C432- 0A ASL
C433- A8 TAY
C434- 28 PLP ; restore status from stack
C435- 50 0F BVC $C446 ; overflow is clear if ... ?
C437- A5 38 LDA $38 ; >> what's in $38?
C439- D0 0D BNE $C448 ; restore stack & return
C43B- 8A TXA
C43C- 45 39 EOR $39 ; >> what's in $39?
C43E- D0 08 BNE $C448 ; restore stack & return
C440- A9 05 LDA #$05
C442- 85 38 STA $38 ; ($38) = $05
C442- 85 38 STA $38
C444- D0 0B BNE $C451
C446- B0 09 BCS $C451 ; carry set if ... ?
C448- 68 PLA ; pull X from stack
C449- AA TAX
C44A- 68 PLA ; pull Y from stack, but
C44B- EA NOP ; throw it away
C44C- 68 PLA ; pull A from stack
C44D- 99 80 C0 STA $C080,Y ; LC RAM bank2, read and wr-protect
C450- 60 RTS
C451- 99 81 C0 STA $C081,Y ; LC RAM bank 2, read ROM
C454- 68 PLA ;
C455- BD 38 06 LDA $0638,X
C458- AA TAX
C459- 68 PLA
C45A- A8 TAY
C45B- 68 PLA
C45C- BD 00 02 LDA $0200,X ; keyboard character buffer?
C45F- 60 RTS
C460- 00 BRK
C461- 00 BRK
C462- 00 BRK
C463- 00 BRK
C464- 00 BRK
C465- 00 BRK
C466- 00 BRK
C467- 00 BRK
C468- 00 BRK
C469- 00 BRK
C46A- 00 BRK
C46B- 00 BRK
C46C- 00 BRK
; SetMouse
C46D- C9 10 CMP #$10 ; interrupt on VBL + interrupt on mouse move?
C46F- B0 3F BCS $C4B0 ; RTS if A >= 0x10
C471- 99 82 C0 STA $C082,Y ; LC RAM bank 2, read ROM, wr-protect RAM
C474- 60 RTS
; ServeMouse
C475- 48 PHA
C476- 18 CLC
C477- 90 39 BCC $C4B2 ; always branches
; ServeMouse cleanup and exit
C479- 99 83 C0 STA $C083,Y ; LC RAM bank 2, read RAM
C47C- BD B8 06 LDA $06B8,X
C47F- 29 0E AND #$0E
C481- D0 01 BNE $C484
C483- 38 SEC
C484- 68 PLA
C485- 60 RTS
; ClampMouse
C486- C9 02 CMP #$02
C488- B0 26 BCS $C4B0 ; RTS if 2 <= the A register
C48A- 99 83 C0 STA $C083,Y ; LC RAM bank 2, read RAM
C48D- 60 RTS
; ReadMouse
C48E- A9 04 LDA #$04
C490- 99 83 C0 STA $C083,Y ; LC RAM bank 2, read RAM
C493- 18 CLC
C494- EA NOP
C495- EA NOP
C496- 60 RTS
; InitMouse
C497- EA NOP
C498- A9 02 LDA #$02
C49A- 99 83 C0 STA $C083,Y ; LC RAM bank 2, read RAM
C49D- 18 CLC
C49E- 60 RTS
; ClearMouse
C49F- EA NOP
C4A0- A9 05 LDA #$05
C4A2- D0 F6 BNE $C49A
; PosMouse
C4A4- EA NOP
C4A5- A9 06 LDA #$06
C4A7- D0 F1 BNE $C49A
; HomeMouse
C4A9- EA NOP
C4AA- A9 07 LDA #$07
C4AC- D0 EC BNE $C49A
C4AE- A2 03 LDX #$03
C4B0- 38 SEC
C4B1- 60 RTS
; ServeMouse main worker
C4B2- 08 PHP
C4B3- A5 00 LDA $00
C4B5- 48 PHA
C4B6- A9 60 LDA #$60
C4B8- 85 00 STA $00
C4BA- 78 SEI
C4BB- 20 00 00 JSR $0000
C4BE- BA TSX
C4BF- 68 PLA
C4C0- 85 00 STA $00
C4C2- BD 00 01 LDA $0100,X
C4C5- 28 PLP
C4C6- AA TAX
C4C7- 0A ASL
C4C8- 0A ASL
C4C9- 0A ASL
C4CA- 0A ASL
C4CB- A8 TAY
C4CC- A9 03 LDA #$03
C4CE- 18 CLC
C4CF- 90 A8 BCC $C479 ; always branches
*/
uint8_t rom[256] = { 0x2c, 0x58, 0xff, 0x70, 0x1B, 0x38, 0x90, 0x18,
0xb8, 0x50, 0x15, 0x01, 0x20, 0xae, 0xae, 0xae,
0xae, 0x00, 0x6d, 0x75, 0x8e, 0x9f, 0xa4, 0x86,