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Add IBM 512KB/2MB 286 Memory Expansion Adapter emulation (#6354)

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This commit is contained in:
WNT50
2025-10-16 22:45:28 +08:00
committed by GitHub
parent 3493d5fc73
commit a8f98772d8
1 changed files with 116 additions and 2 deletions
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118
src/machine/m_ps2_mca.c
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@@ -99,6 +99,7 @@ static struct ps2_t {
uint8_t mem_pos_regs[8];
uint8_t mem_2mb_pos_regs[8];
uint8_t mem_2mb_pos_cache[1024];
int pending_cache_miss;
@@ -1061,6 +1062,111 @@ ps2_mem_expansion_feedb(UNUSED(void *priv))
return (ps2.mem_pos_regs[2] & 1);
}
static uint8_t
ps2_mem_2mb_cache_read(void)
{
uint8_t cache_addr_lo = ps2.mem_2mb_pos_regs[6];
uint8_t cache_addr_hi = ps2.mem_2mb_pos_regs[7];
uint16_t cache_addr = (cache_addr_hi << 8) | cache_addr_lo;
ps2_mca_log("ps2_mem_2mb_cache_read: addr=%04x %02x %04x:%04x\n", cache_addr, ps2.mem_2mb_pos_cache[cache_addr & 0x3ff], CS, cpu_state.pc);
return ps2.mem_2mb_pos_cache[cache_addr & 0x3ff];
}
static void
ps2_mem_2mb_cache_write(uint8_t val)
{
uint8_t cache_addr_lo = ps2.mem_2mb_pos_regs[6];
uint8_t cache_addr_hi = ps2.mem_2mb_pos_regs[7];
uint16_t cache_addr = (cache_addr_hi << 8) | cache_addr_lo;
ps2_mca_log("ps2_mem_2mb_cache_write: addr=%04x %02x %04x:%04x\n", cache_addr, val, CS, cpu_state.pc);
ps2.mem_2mb_pos_cache[cache_addr & 0x3ff] = val;
}
static uint8_t
ps2_mem_2mb_expansion_read(int port, UNUSED(void *priv))
{
if (port == 0x103)
ps2.mem_2mb_pos_regs[3] = ps2_mem_2mb_cache_read();
return ps2.mem_2mb_pos_regs[port & 7];
}
static void
ps2_mem_2mb_expansion_write(int port, uint8_t val, UNUSED(void *priv))
{
if (port < 0x102)
return;
if (port == 0x103)
ps2_mem_2mb_cache_write(val);
else if (port == 0x102)
ps2.mem_2mb_pos_regs[2] = (ps2.mem_2mb_pos_regs[2] & 0xfe) | (val & 0x01);
else if (port == 0x105)
ps2.mem_2mb_pos_regs[5] = (ps2.mem_2mb_pos_regs[2] & 0x01) | (val & 0xfe);
else
ps2.mem_2mb_pos_regs[port & 7] = val;
if (ps2.mem_2mb_pos_regs[2] & 1)
mem_mapping_enable(&ps2.expansion_mapping);
else
mem_mapping_disable(&ps2.expansion_mapping);
}
static uint8_t
ps2_mem_2mb_expansion_feedb(UNUSED(void *priv))
{
return (ps2.mem_2mb_pos_regs[2] & 1);
}
static void
ps2_mca_mem_fefe_init(int start_mb)
{
uint32_t planar_size;
uint32_t expansion_start;
planar_size = (start_mb - 1) << 20;
expansion_start = start_mb << 20;
mem_mapping_set_addr(&ram_high_mapping, 0x100000, planar_size);
ps2.mem_2mb_pos_regs[0] = 0xfe;
ps2.mem_2mb_pos_regs[1] = 0xfe;
switch ((mem_size / 1024) - start_mb) {
case 0:/*256Kx2 = 11 11 11 10*/
ps2.mem_2mb_pos_regs[2] = 0xfe;
ps2.mem_2mb_pos_regs[5] = 0xfe;
break;
case 1:/*256Kx4 = 11 11 10 10*/
ps2.mem_2mb_pos_regs[2] = 0xfa;
ps2.mem_2mb_pos_regs[5] = 0xfe;
break;
case 2:/*256Kx8 = 10 10 10 10*/
ps2.mem_2mb_pos_regs[2] = 0xaa;
ps2.mem_2mb_pos_regs[5] = 0xfe;
break;
default:
break;
}
mca_add(ps2_mem_2mb_expansion_read, ps2_mem_2mb_expansion_write, ps2_mem_2mb_expansion_feedb, NULL, NULL);
mem_mapping_add(&ps2.expansion_mapping,
expansion_start,
(mem_size - (start_mb << 10)) << 10,
mem_read_ram,
mem_read_ramw,
mem_read_raml,
mem_write_ram,
mem_write_ramw,
mem_write_raml,
&ram[expansion_start],
MEM_MAPPING_INTERNAL,
NULL);
mem_mapping_disable(&ps2.expansion_mapping);
}
static void
ps2_mca_mem_fffc_init(int start_mb)
{
@@ -1188,7 +1294,11 @@ ps2_mca_board_model_50_init(void)
if (mem_size > 2048) {
/* Only 2 MB supported on planar, create a memory expansion card for the rest */
ps2_mca_mem_fffc_init(2);
if (mem_size > 4096) {
ps2_mca_mem_fffc_init(2);
} else {
ps2_mca_mem_fefe_init(2);
}
}
if (gfxcard[0] == VID_INTERNAL)
@@ -1235,7 +1345,11 @@ ps2_mca_board_model_60_init(void)
if (mem_size > 4096) {
/* Only 4 MB supported on planar, create a memory expansion card for the rest */
ps2_mca_mem_fffc_init(4);
if (mem_size > 6144) {
ps2_mca_mem_fffc_init(4);
} else {
ps2_mca_mem_fefe_init(4);
}
}
device_add(&ps2_nvr_55ls_device);