MemHandle MEM_AllocatePages(Bitu pages,bool sequence) {
MemHandle ret;
if (!pages) return 0;
if (sequence) {
Bitu index=BestMatch(pages);
if (!index) return 0;
MemHandle * next=&ret;
while (pages) {
*next=index;
next=&memory.mhandles[index];
index++;pages--;
}
*next=-1;
} else {
if (MEM_FreeTotal()<pages) return 0;
MemHandle * next=&ret;
while (pages) {
Bitu index=BestMatch(1);
if (!index) E_Exit("MEM:corruption during allocate");
while (pages && (!memory.mhandles[index])) {
*next=index;
next=&memory.mhandles[index];
index++;pages--;
}
*next=-1; //Invalidate it in case we need another match
}
}
return ret;
}
Bitu XMS_QueryFreeMemory(Bit16u& largestFree, Bit16u& totalFree) {
/* Scan the tree for free memory and find largest free block */
totalFree=(Bit16u)(MEM_FreeTotal()*4);
largestFree=(Bit16u)(MEM_FreeLargest()*4);
if (!totalFree) return XMS_OUT_OF_SPACE;
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;
}
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;
}
static Bit16u EMM_GetFreePages(void) {
Bitu count=MEM_FreeTotal()/4;
if (count>0x7fff) count=0x7fff;
return (Bit16u)count;
}