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;
}
static Bit8u EMM_ReallocatePages(Bit16u handle,Bit16u & pages) {
/* Check for valid handle */
if (!ValidHandle(handle)) return EMM_INVALID_HANDLE;
if (emm_handles[handle].pages != 0) {
/* Check for enough pages */
if (!MEM_ReAllocatePages(emm_handles[handle].mem,pages*4,false)) return EMM_OUT_OF_LOG;
} else {
MemHandle mem = MEM_AllocatePages(pages*4,false);
if (!mem) E_Exit("EMS:Memory allocation failure during reallocation");
emm_handles[handle].mem = mem;
}
/* Update size */
emm_handles[handle].pages=pages;
return EMM_NO_ERROR;
}
Bitu XMS_AllocateMemory(Bitu size, Bit16u& handle) { // size = kb
/* Find free handle */
Bit16u index=1;
while (!xms_handles[index].free) {
if (++index>=XMS_HANDLES) return XMS_OUT_OF_HANDLES;
}
MemHandle mem;
if (size!=0) {
Bitu pages=(size/4) + ((size & 3) ? 1 : 0);
mem=MEM_AllocatePages(pages,true);
if (!mem) return XMS_OUT_OF_SPACE;
} else {
mem=MEM_GetNextFreePage();
if (mem==0) LOG(LOG_MISC,LOG_ERROR)("XMS:Allocate zero pages with no memory left");
}
xms_handles[index].free=false;
xms_handles[index].mem=mem;
xms_handles[index].locked=0;
xms_handles[index].size=size;
handle=index;
return 0;
}
static Bit8u EMM_AllocateMemory(Bit16u pages,Bit16u & dhandle,bool can_allocate_zpages) {
/* Check for 0 page allocation */
if (!pages) {
if (!can_allocate_zpages) return EMM_ZERO_PAGES;
}
/* Check for enough free pages */
if ((MEM_FreeTotal()/ 4) < pages) { return EMM_OUT_OF_LOG;}
Bit16u handle = 1;
/* Check for a free handle */
while (emm_handles[handle].pages != NULL_HANDLE) {
if (++handle >= EMM_MAX_HANDLES) {return EMM_OUT_OF_HANDLES;}
}
MemHandle mem = 0;
if (pages) {
mem = MEM_AllocatePages(pages*4,false);
if (!mem) E_Exit("EMS:Memory allocation failure");
}
emm_handles[handle].pages = pages;
emm_handles[handle].mem = mem;
/* Change handle only if there is no error. */
dhandle = handle;
return EMM_NO_ERROR;
}
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;
}
