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AO486: Improve memory initialization (#942)

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This commit is contained in:
humply
2024-12-19 06:38:14 +01:00
committed by GitHub
parent b79e95ee97
commit 7e40f55c37
1 changed files with 23 additions and 4 deletions
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27
support/x86/x86.cpp
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@@ -299,6 +299,17 @@ static void x86_dma_recvbuf(uint32_t address, uint32_t length, uint32_t *data)
DisableIO();
}
static int mem_set(uint32_t offset, uint8_t fill_byte, uint32_t size)
{
void *buf = shmem_map(SHMEM_ADDR + offset, size);
if (!buf) return 0;
memset(buf, fill_byte, size);
shmem_unmap(buf, size);
return 1;
}
static int load_bios(const char* name, uint8_t index)
{
printf("BIOS: %s\n", name);
@@ -521,6 +532,10 @@ void x86_init()
if (is_x86())
{
// PC-DOS/MS-DOS/Win3.x/Win9x recognize 0xFF as free memory (UMA),
// otherwise it can be incorrectly interpreted as used by Option RAM (non-free).
mem_set(0x0, 0xFF, 0x100000); // up to 1Mb
mem_set(0xCE00, 0x00, 0x200); // mark shr_rgn as non-free
load_bios(user_io_make_filepath(home, "boot0.rom"), 0);
load_bios(user_io_make_filepath(home, "boot1.rom"), 1);
}
@@ -540,6 +555,10 @@ void x86_init()
//-------------------------------------------------------------------------- rtc
// memcfg 0: 256MB
// memcfg 1: 16MB
uint8_t memcfg = is_x86() ? user_io_status_get("[11]") : 1;
unsigned char translate_mode = 1; //LBA
translate_mode = (translate_mode << 6) | (translate_mode << 4) | (translate_mode << 2) | translate_mode;
@@ -574,7 +593,7 @@ void x86_init()
0x80, //0x15: base memory in 1k LSB
0x02, //0x16: base memory in 1k MSB
0x00, //0x17: memory size above 1m in 1k LSB
0xFC, //0x18: memory size above 1m in 1k MSB
(uint8_t)(memcfg ? 0x3C : 0xFC), //0x18: memory size above 1m in 1k MSB
0x00, //0x19: extended hd types 1/2; type 47d (unused)
0x00, //0x1A: extended hd types 2/2 (unused)
@@ -604,13 +623,13 @@ void x86_init()
0x00, //0x2F: checksum LSB
0x00, //0x30: memory size above 1m in 1k LSB
0x3C, //0x31: memory size above 1m in 1k MSB
(uint8_t)(memcfg ? 0x3C : 0xFC), //0x31: memory size above 1m in 1k MSB
0x20, //0x32: IBM century
0x00, //0x33: ?
0x80, //0x34: memory size above 16m in 64k LSB
0x0E, //0x35: memory size above 16m in 64k MSB; 256-8 MB
(uint8_t)(memcfg ? 0x00 : 0x80), //0x34: memory size above 16m in 64k LSB
(uint8_t)(memcfg ? 0x00 : 0x0E), //0x35: memory size above 16m in 64k MSB; 256-8 MB
0x00, //0x36: ?
0x20, //0x37: IBM PS/2 century