Bitu XMS_FreeMemory(Bitu handle) {
if (InvalidHandle(handle)) return XMS_INVALID_HANDLE;
MEM_ReleasePages(xms_handles[handle].mem);
xms_handles[handle].mem=-1;
xms_handles[handle].size=0;
xms_handles[handle].free=true;
return 0;
}
static Bit8u EMM_AllocateSystemHandle(Bit16u pages) {
/* Check for enough free pages */
if ((MEM_FreeTotal()/ 4) < pages) { return EMM_OUT_OF_LOG;}
Bit16u handle = 0; // emm system handle (reserved for OS usage)
/* Release memory if already allocated */
if (emm_handles[handle].pages != NULL_HANDLE) {
MEM_ReleasePages(emm_handles[handle].mem);
}
MemHandle mem = MEM_AllocatePages(pages*4,false);
if (!mem) E_Exit("EMS:System handle memory allocation failure");
emm_handles[handle].pages = pages;
emm_handles[handle].mem = mem;
return EMM_NO_ERROR;
}
/**
* @brief Allocates a number of pages.
* @param _address_space [in] The address space where the page will be mapped.
* @param _address [in] The virtual address where the page will be mapped.
* @param _number_of_pages [in] The number of pages to allocate.
* @return The virtual address reserved, 0 otherwise.
*/
PUBLIC VIRTUAL XKY_PAGE_Alloc(IN ADDRESS_SPACE _address_space, IN VIRTUAL _address, IN dword _number_of_pages)
{
ADDRESS_SPACE current = ADDRESS_SPACE_GetCurrent();
ADDRESS_SPACE_ResetToKernelSpace();
//Do page allocation
PHYSICAL pages = MEM_AllocPages(_number_of_pages, UserMode);
if(!pages)
{
ADDRESS_SPACE_SwitchTo(current);
return false;
}
bool success = ADDRESS_SPACE_Map(_address_space, pages, _address, _number_of_pages, UserMode, ReadWrite, true);
if(!success)
{
MEM_ReleasePages(pages, _number_of_pages);
}
ADDRESS_SPACE_SwitchTo(current);
return success?_address:0;
}
bool MEM_ReAllocatePages(MemHandle & handle,Bitu pages,bool sequence) {
if (handle<=0) {
if (!pages) return true;
handle=MEM_AllocatePages(pages,sequence);
return (handle>0);
}
if (!pages) {
MEM_ReleasePages(handle);
handle=-1;
return true;
}
MemHandle index=handle;
MemHandle last;Bitu old_pages=0;
while (index>0) {
old_pages++;
last=index;
index=memory.mhandles[index];
}
if (old_pages == pages) return true;
if (old_pages > pages) {
/* Decrease size */
pages--;index=handle;old_pages--;
while (pages) {
index=memory.mhandles[index];
pages--;old_pages--;
}
MemHandle next=memory.mhandles[index];
memory.mhandles[index]=-1;
index=next;
while (old_pages) {
next=memory.mhandles[index];
memory.mhandles[index]=0;
index=next;
old_pages--;
}
return true;
} else {
/* Increase size, check for enough free space */
Bitu need=pages-old_pages;
if (sequence) {
index=last+1;
Bitu free=0;
while ((index<(MemHandle)memory.pages) && !memory.mhandles[index]) {
index++;free++;
}
if (free>=need) {
/* Enough space allocate more pages */
index=last;
while (need) {
memory.mhandles[index]=index+1;
need--;index++;
}
memory.mhandles[index]=-1;
return true;
} else {
/* Not Enough space allocate new block and copy */
MemHandle newhandle=MEM_AllocatePages(pages,true);
if (!newhandle) return false;
MEM_BlockCopy(newhandle*4096,handle*4096,old_pages*4096);
MEM_ReleasePages(handle);
handle=newhandle;
return true;
}
} else {
MemHandle rem=MEM_AllocatePages(need,false);
if (!rem) return false;
memory.mhandles[last]=rem;
return true;
}
}
return 0;
}
