bool DOS_AllocateMemory(Bit16u * segment,Bit16u * blocks) {
DOS_CompressMemory();
Bit16u bigsize=0;
Bit16u mem_strat=memAllocStrategy;
Bit16u mcb_segment=dos.firstMCB;
Bit16u umb_start=dos_infoblock.GetStartOfUMBChain();
if (umb_start==UMB_START_SEG) {
/* start with UMBs if requested (bits 7 or 6 set) */
if (mem_strat&0xc0) mcb_segment=umb_start;
} else if (umb_start!=0xffff) LOG(LOG_DOSMISC,LOG_ERROR)("Corrupt UMB chain: %x",umb_start);
DOS_MCB mcb(0);
DOS_MCB mcb_next(0);
DOS_MCB psp_mcb(dos.psp()-1);
char psp_name[9];
psp_mcb.GetFileName(psp_name);
Bit16u found_seg=0,found_seg_size=0;
for (;;) {
mcb.SetPt(mcb_segment);
if (mcb.GetPSPSeg()==MCB_FREE) {
/* Check for enough free memory in current block */
Bit16u block_size=mcb.GetSize();
if (block_size<(*blocks)) {
if (bigsize<block_size) {
/* current block is largest block that was found,
but still not as big as requested */
bigsize=block_size;
}
} else if ((block_size==*blocks) && ((mem_strat & 0x3f)<2)) {
/* MCB fits precisely, use it if search strategy is firstfit or bestfit */
mcb.SetPSPSeg(dos.psp());
*segment=mcb_segment+1;
return true;
} else {
switch (mem_strat & 0x3f) {
case 0: /* firstfit */
mcb_next.SetPt((Bit16u)(mcb_segment+*blocks+1));
mcb_next.SetPSPSeg(MCB_FREE);
mcb_next.SetType(mcb.GetType());
mcb_next.SetSize(block_size-*blocks-1);
mcb.SetSize(*blocks);
mcb.SetType(0x4d);
mcb.SetPSPSeg(dos.psp());
mcb.SetFileName(psp_name);
//TODO Filename
*segment=mcb_segment+1;
return true;
case 1: /* bestfit */
if ((found_seg_size==0) || (block_size<found_seg_size)) {
/* first fitting MCB, or smaller than the last that was found */
found_seg=mcb_segment;
found_seg_size=block_size;
}
break;
default: /* everything else is handled as lastfit by dos */
/* MCB is large enough, note it down */
found_seg=mcb_segment;
found_seg_size=block_size;
break;
}
}
}
/* Onward to the next MCB if there is one */
if (mcb.GetType()==0x5a) {
if ((mem_strat&0x80) && (umb_start==UMB_START_SEG)) {
/* bit 7 set: try high memory first, then low */
mcb_segment=dos.firstMCB;
mem_strat&=(~0xc0);
} else {
/* finished searching all requested MCB chains */
if (found_seg) {
/* a matching MCB was found (cannot occur for firstfit) */
if ((mem_strat & 0x3f)==0x01) {
/* bestfit, allocate block at the beginning of the MCB */
mcb.SetPt(found_seg);
mcb_next.SetPt((Bit16u)(found_seg+*blocks+1));
mcb_next.SetPSPSeg(MCB_FREE);
mcb_next.SetType(mcb.GetType());
mcb_next.SetSize(found_seg_size-*blocks-1);
mcb.SetSize(*blocks);
mcb.SetType(0x4d);
mcb.SetPSPSeg(dos.psp());
mcb.SetFileName(psp_name);
//TODO Filename
*segment=found_seg+1;
} else {
/* lastfit, allocate block at the end of the MCB */
mcb.SetPt(found_seg);
if (found_seg_size==*blocks) {
/* use the whole block */
mcb.SetPSPSeg(dos.psp());
//Not consistent with line 124. But how many application will use this information ?
mcb.SetFileName(psp_name);
*segment = found_seg+1;
return true;
}
*segment = found_seg+1+found_seg_size - *blocks;
mcb_next.SetPt((Bit16u)(*segment-1));
mcb_next.SetSize(*blocks);
mcb_next.SetType(mcb.GetType());
mcb_next.SetPSPSeg(dos.psp());
mcb_next.SetFileName(psp_name);
// Old Block
mcb.SetSize(found_seg_size-*blocks-1);
mcb.SetPSPSeg(MCB_FREE);
mcb.SetType(0x4D);
}
return true;
}
/* no fitting MCB found, return size of largest block */
*blocks=bigsize;
DOS_SetError(DOSERR_INSUFFICIENT_MEMORY);
return false;
}
} else mcb_segment+=mcb.GetSize()+1;
}
return false;
}
bool DOS_AllocateMemory(Bit16u * segment, Bit16u * reqBlocks)
{
DOS_CompressMemory(); // Mainly to check the NCB chain
Bit16u bigsize = 0;
Bit16u mem_strat = memAllocStrategy;
Bit16u mcb_segment = dos.firstMCB;
Bit16u umb_start = dos_infoblock.GetStartOfUMBChain();
if (umb_start == EndConvMem && (mem_strat&0xc0)) // Start with UMBs if requested (bits 7 or 6 set)
mcb_segment = umb_start;
DOS_MCB mcb(0);
DOS_MCB mcb_next(0);
DOS_MCB psp_mcb(dos.psp()-1);
char psp_name[9];
psp_mcb.GetFileName(psp_name);
Bit16u foundSeg = 0, foundSize = 0;
for (;;)
{
mcb.SetPt(mcb_segment);
if (mcb.GetPSPSeg() == MCB_FREE)
{
Bit16u block_size = mcb.GetSize();
if (block_size < (*reqBlocks)) // Check for enough free memory in current block
{
if (bigsize < block_size) // Current block is largest block that was found, but still not as big as requested
bigsize = block_size;
}
else if ((block_size == *reqBlocks) && ((mem_strat & 0x3f) < 2)) // MCB fits precisely, use it if search strategy is firstfit or bestfit
{
mcb.SetPSPSeg(dos.psp());
mcb.SetFileName(psp_name);
*segment = mcb_segment+1;
return true;
}
else // Found block is larger than requested
{
switch (mem_strat & 0x3f)
{
case 0: // Firstfit
mcb_next.SetPt((Bit16u)(mcb_segment+*reqBlocks+1));
mcb_next.SetPSPSeg(MCB_FREE);
mcb_next.SetType(mcb.GetType());
mcb_next.SetSize(block_size-*reqBlocks-1);
mcb.SetSize(*reqBlocks);
mcb.SetType('M');
mcb.SetPSPSeg(dos.psp());
mcb.SetFileName(psp_name);
*segment = mcb_segment+1;
return true;
case 1: // Bestfit
if ((foundSize == 0) || (block_size < foundSize)) // First fitting MCB, or smaller than the last that was found
{
foundSeg = mcb_segment;
foundSize = block_size;
}
break;
default: // Everything else is handled as lastfit by DOS
foundSeg = mcb_segment; // MCB is large enough, note it down
foundSize = block_size;
break;
}
}
}
if (mcb.GetType() == 'Z') // Onward to the next MCB if there is one
{
if ((mem_strat&0x80) && (umb_start == EndConvMem))
{
mcb_segment = dos.firstMCB; // Bit 7 set: try upper memory first, then low
mem_strat &= (~0xc0);
}
else // Finished searching all requested MCB chains
{
if (foundSeg) // A matching MCB was found (cannot occur for firstfit)
{
if ((mem_strat & 0x3f) == 1) // Bestfit, allocate block at the beginning of the MCB
{
mcb.SetPt(foundSeg);
mcb_next.SetPt((Bit16u)(foundSeg+*reqBlocks+1));
mcb_next.SetPSPSeg(MCB_FREE);
mcb_next.SetType(mcb.GetType());
mcb_next.SetSize(foundSize-*reqBlocks-1);
mcb.SetSize(*reqBlocks);
mcb.SetType('M');
mcb.SetPSPSeg(dos.psp());
mcb.SetFileName(psp_name);
*segment = foundSeg+1;
}
else // Lastfit, allocate block at the end of the MCB
{
mcb.SetPt(foundSeg);
if (foundSize == *reqBlocks) // If requested size
{
mcb.SetPSPSeg(dos.psp());
mcb.SetFileName(psp_name);
*segment = foundSize+1;
return true;
}
*segment = foundSeg+1+foundSize-*reqBlocks;
mcb_next.SetPt((Bit16u)(*segment-1));
mcb_next.SetSize(*reqBlocks);
mcb_next.SetType(mcb.GetType());
mcb_next.SetPSPSeg(dos.psp());
mcb_next.SetFileName(psp_name);
mcb.SetSize(foundSize-*reqBlocks-1);
mcb.SetPSPSeg(MCB_FREE);
mcb.SetType('M');
}
return true;
}
*reqBlocks = bigsize; // No fitting MCB found, return size of largest block
DOS_SetError(DOSERR_INSUFFICIENT_MEMORY);
return false;
}
}
else
mcb_segment += mcb.GetSize()+1;
}
return false;
}
