static Bit8u EMM_MapPage(Bitu phys_page,Bit16u handle,Bit16u log_page) {
// LOG_MSG("EMS MapPage handle %d phys %d log %d",handle,phys_page,log_page);
/* Check for too high physical page */
if (phys_page>=EMM_MAX_PHYS) return EMM_ILL_PHYS;
/* unmapping doesn't need valid handle (as handle isn't used) */
if (log_page==NULL_PAGE) {
/* Unmapping */
emm_mappings[phys_page].handle=NULL_HANDLE;
emm_mappings[phys_page].page=NULL_PAGE;
for (Bitu i=0;i<4;i++)
PAGING_MapPage(EMM_PAGEFRAME4K+phys_page*4+i,EMM_PAGEFRAME4K+phys_page*4+i);
PAGING_ClearTLB();
return EMM_NO_ERROR;
}
/* Check for valid handle */
if (!ValidHandle(handle)) return EMM_INVALID_HANDLE;
if (log_page<emm_handles[handle].pages) {
/* Mapping it is */
emm_mappings[phys_page].handle=handle;
emm_mappings[phys_page].page=log_page;
MemHandle memh=MEM_NextHandleAt(emm_handles[handle].mem,log_page*4);;
for (Bitu i=0;i<4;i++) {
PAGING_MapPage(EMM_PAGEFRAME4K+phys_page*4+i,memh);
memh=MEM_NextHandle(memh);
}
PAGING_ClearTLB();
return EMM_NO_ERROR;
} else {
/* Illegal logical page it is */
return EMM_LOG_OUT_RANGE;
}
}
static Bit8u EMM_MapSegment(Bitu segment,Bit16u handle,Bit16u log_page) {
// LOG_MSG("EMS MapSegment handle %d segment %d log %d",handle,segment,log_page);
if (((segment>=0xa000) && (segment<0xb000)) || ((segment>=EMM_PAGEFRAME-0x1000) && (segment<EMM_PAGEFRAME+0x1000))) {
Bit32s tphysPage = ((Bit32s)segment-EMM_PAGEFRAME)/(0x1000/EMM_MAX_PHYS);
/* unmapping doesn't need valid handle (as handle isn't used) */
if (log_page==NULL_PAGE) {
/* Unmapping */
if ((tphysPage>=0) && (tphysPage<EMM_MAX_PHYS)) {
emm_mappings[tphysPage].handle=NULL_HANDLE;
emm_mappings[tphysPage].page=NULL_PAGE;
} else {
emm_segmentmappings[segment>>10].handle=NULL_HANDLE;
emm_segmentmappings[segment>>10].page=NULL_PAGE;
}
for (Bitu i=0;i<4;i++)
PAGING_MapPage(segment*16/4096+i,segment*16/4096+i);
PAGING_ClearTLB();
return EMM_NO_ERROR;
}
/* Check for valid handle */
if (!ValidHandle(handle)) return EMM_INVALID_HANDLE;
if (log_page<emm_handles[handle].pages) {
/* Mapping it is */
if ((tphysPage>=0) && (tphysPage<EMM_MAX_PHYS)) {
emm_mappings[tphysPage].handle=handle;
emm_mappings[tphysPage].page=log_page;
} else {
emm_segmentmappings[segment>>10].handle=handle;
emm_segmentmappings[segment>>10].page=log_page;
}
MemHandle memh=MEM_NextHandleAt(emm_handles[handle].mem,log_page*4);;
for (Bitu i=0;i<4;i++) {
PAGING_MapPage(segment*16/4096+i,memh);
memh=MEM_NextHandle(memh);
}
PAGING_ClearTLB();
return EMM_NO_ERROR;
} else {
/* Illegal logical page it is */
return EMM_LOG_OUT_RANGE;
void MEM_A20_Enable(bool enabled) {
Bitu phys_base=enabled ? (1024/4) : 0;
for (Bitu i=0;i<16;i++) PAGING_MapPage((1024/4)+i,phys_base+i);
memory.a20.enabled=enabled;
}
