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Merge remote-tracking branch 'upstream/master' into feature/ich2

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This commit is contained in:
Jasmine Iwanek
2024-02-22 18:48:16 -05:00
parent 089511fd0e b728172edc
commit 78a56002c1
277 changed files with 24707 additions and 8812 deletions
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47
src/dma.c
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@@ -950,16 +950,47 @@ dma_page_read(uint16_t addr, UNUSED(void *priv))
uint8_t convert[8] = CHANNELS;
uint8_t ret = 0xff;
addr &= 0x0f;
ret = dmaregs[2][addr];
if (((addr & 0xfffc) == 0x80) && (CS == 0xf000) &&
((cpu_state.pc & 0xfffffff8) == 0x00007278) &&
!strcmp(machine_get_internal_name(), "megapc")) switch (addr) {
/* The Amstrad MegaPC Quadtel BIOS times a sequence of:
mov ax,di
div bx
And expects this value to be at least 0x06e0 for 20 MHz,
and at least 0x0898 for 25 MHz, everything below 0x06e0
is assumed to be 16 MHz. Given that for some reason, this
does not occur on 86Box, we have to work around it here,
we return 0x0580 for 16 MHz, because it logically follows
in the sequence (0x06e0 = 0x0898 * (20 / 25), and
0x0580 = 0x06e0 * (16 / 20)). */
case 0x0081:
if (cpu_busspeed >= 25000000)
ret = 0x98;
else if (cpu_busspeed >= 20000000)
ret = 0xe0;
else
ret = 0x80;
break;
case 0x0082:
if (cpu_busspeed >= 25000000)
ret = 0x08;
else if (cpu_busspeed >= 20000000)
ret = 0x06;
else
ret = 0x05;
break;
} else {
addr &= 0x0f;
ret = dmaregs[2][addr];
if (addr >= 8)
addr = convert[addr & 0x07] | 4;
else
addr = convert[addr & 0x07];
if (addr >= 8)
addr = convert[addr & 0x07] | 4;
else
addr = convert[addr & 0x07];
if (addr < 8)
ret = dma[addr].page_l;
if (addr < 8)
ret = dma[addr].page_l;
}
return ret;
}