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Some changes to a20 line handling and some cleaning up.

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@905
This commit is contained in:
Sjoerd van der Berg 2003-04-13 18:21:49 +00:00
parent 7cbbca92f4
commit ae0b157a7b
1 changed files with 22 additions and 19 deletions
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41
src/hardware/memory.cpp
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@ -274,24 +274,33 @@ static void AllocateMem_WriteHandler(PhysPt pt,Bit8u val)
// A20 Line Handlers
static Bit8u controlport_data = 0;
static bool a20_enabled;
bool MEM_A20_Enabled(void) {
return a20_enabled;
}
void MEM_A20_Enable(bool enable) {
if (a20_enabled==enable) return;
a20_enabled=enable;
if (enable) {
MEM_SetupMapping(PAGE_COUNT(1024*1024),PAGE_COUNT(64*1024),((Bit8u*)memory)+1024*1024);
} else {
MEM_SetupMapping(PAGE_COUNT(1024*1024),PAGE_COUNT(64*1024),memory);
}
LOG(LOG_MISC,"A20 Line is %s",enable ? "Enabled" : "Disabled");
}
static void write_p92(Bit32u port,Bit8u val) {
// Bit 0 = system reset (switch back to real mode)
if (val&1) E_Exit("XMS: CPU reset via port 0x92 not supported.");
if ((val&2) & !(controlport_data&2)) {
// ensable HMA
MEM_SetupMapping(PAGE_COUNT(1024*1024),PAGE_COUNT(64*1024),((Bit8u*)memory)+1024*1024);
};
if (!(val&2) && (controlport_data&2)) {
// disable HMA
MEM_SetupMapping(PAGE_COUNT(1024*1024),PAGE_COUNT(64*1024),memory);
};
controlport_data = val;
};
controlport_data = val & ~2;
MEM_A20_Enable((val & 2)>0);
}
static Bit8u read_p92(Bit32u port) {
return controlport_data;
};
return controlport_data | a20_enabled ? 0x02 : 0;
}
static void MEM_ShutDown(Section * sec) {
for (Bitu i=0; i<C_MEM_MAX_SIZE; i++) {
@ -304,13 +313,6 @@ static void MEM_ShutDown(Section * sec) {
void MEM_Init(Section * sect) {
/* Init all tables */
Bitu i;
i=MAX_PAGES;
for (i=0;i<MAX_PAGES;i++) {
ReadHostTable[i]=0;
WriteHostTable[i]=0;
ReadHandlerTable[i]=&Default_ReadHandler;
WriteHandlerTable[i]=&Default_WriteHandler;
}
/* Allocate the first mb of memory + hma */
memory=(Bit8u *)malloc(1024*1024+64*1024);
if (!memory) {
@ -320,6 +322,7 @@ void MEM_Init(Section * sect) {
/* Setup tables for first mb */
MEM_SetupMapping(0,PAGE_COUNT(1024*1024),memory);
/* Setup tables for HMA Area */
a20_enabled=false;
MEM_SetupMapping(PAGE_COUNT(1024*1024),PAGE_COUNT(64*1024),memory);
// Setup default handlers for unallocated xms
for (Bitu p=PAGE_COUNT((1024+64)*1024);p<MAX_PAGES;p++) {