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Disable special segment selector pushing behavior on Pentium onwards, fixes MSVC builds of ReactOS.

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This commit is contained in:
OBattler
2025-03-16 18:37:32 +01:00
parent 371866063b
commit 1c5d432d3c
3 changed files with 57 additions and 46 deletions
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79
src/cpu/cpu.c
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@@ -209,6 +209,7 @@ int is286;
int is386;
int is6117;
int is486 = 1;
int is586 = 0;
int cpu_isintel;
int cpu_iscyrix;
int hascache;
@@ -552,6 +553,8 @@ cpu_set(void)
cpu_16bitbus = (cpu_s->cpu_type == CPU_286) || (cpu_s->cpu_type == CPU_386SX) || (cpu_s->cpu_type == CPU_486SLC) || (cpu_s->cpu_type == CPU_IBM386SLC) || (cpu_s->cpu_type == CPU_IBM486SLC);
cpu_64bitbus = (cpu_s->cpu_type >= CPU_WINCHIP);
is586 = cpu_64bitbus || (cpu_s->cpu_type == CPU_P24T);
if (cpu_s->multi)
cpu_busspeed = cpu_s->rspeed / cpu_s->multi;
else
@@ -4303,47 +4306,47 @@ cpu_write(uint16_t addr, uint8_t val, UNUSED(void *priv))
static uint8_t
cpu_read(uint16_t addr, UNUSED(void *priv))
{
uint8_t ret = 0xff;
if (addr == 0xf007)
return 0x7f;
ret = 0x7f;
else if ((addr < 0xf0) && (addr & 1)) switch (cyrix_addr) {
case 0xc0:
ret = ccr0;
break;
case 0xc1:
ret = ccr1;
break;
case 0xc2:
ret = ccr2;
break;
case 0xc3:
ret = ccr3;
break;
case 0xe8:
ret = ((ccr3 & 0xf0) == 0x10) ? ccr4 : 0xff;
break;
case 0xe9:
ret = ((ccr3 & 0xf0) == 0x10) ? ccr5 : 0xff;
break;
case 0xea:
ret = ((ccr3 & 0xf0) == 0x10) ? ccr6 : 0xff;
break;
case 0xeb:
ret = ccr7;
break;
case 0xfe:
ret = cpu_s->cyrix_id & 0xff;
break;
case 0xff:
ret = cpu_s->cyrix_id >> 8;
break;
if (addr >= 0xf0)
return 0xff; /* FPU stuff */
if (addr & 1) {
switch (cyrix_addr) {
case 0xc0:
return ccr0;
case 0xc1:
return ccr1;
case 0xc2:
return ccr2;
case 0xc3:
return ccr3;
case 0xe8:
return ((ccr3 & 0xf0) == 0x10) ? ccr4 : 0xff;
case 0xe9:
return ((ccr3 & 0xf0) == 0x10) ? ccr5 : 0xff;
case 0xea:
return ((ccr3 & 0xf0) == 0x10) ? ccr6 : 0xff;
case 0xeb:
return ccr7;
case 0xfe:
return cpu_s->cyrix_id & 0xff;
case 0xff:
return cpu_s->cyrix_id >> 8;
default:
break;
}
if ((cyrix_addr & 0xf0) == 0xc0)
return 0xff;
if (cyrix_addr == 0x20 && (cpu_s->cpu_type == CPU_Cx5x86))
return 0xff;
default:
break;
}
return 0xff;
return ret;
}
void