198 lines
4.3 KiB
C
198 lines
4.3 KiB
C
// vm.c
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//
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// simple minded virtual memory implemenation
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// there is no code to do the OS2 version...
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#include <stdio.h>
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#include <fcntl.h>
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#include <io.h>
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#include <sys\types.h>
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#include <sys\stat.h>
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#include <malloc.h>
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#include <string.h>
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#if defined(OS2)
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#define INCL_NOCOMMON
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#define INCL_DOSPROCESS
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#define INCL_DOSSEMAPHORES
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#define INCL_DOSFILEMGR
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#define INCL_DOSERRORS
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#define INCL_DOSMISC
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#include <os2.h>
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#else
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#include <windows.h>
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#endif
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#include "hungary.h"
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#include "vm.h"
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#include "sbrproto.h"
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#include "errors.h"
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#define CB_PAGE_SIZE 2048 // 4k pages
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#define C_LOCKS_MAX 16 // up to 16 pages may be locked in ram
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#define C_PAGES_MAX 8192 // up to 4k pages resident
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#define C_FREE_LIST_MAX 256 // keep free lists for items up to 256 bytes
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#define GRP_MAX 16 // max number of memory groups
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typedef WORD VPG; // virtual page number
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typedef VA far *LPVA; // far pointer to VA
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// virtual address arithmetic
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//
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// #define VpgOfVa(va) ((WORD)((va>>12)))
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// this is really the same as the above but it assumes that the high byte
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// of the long is all zero's and it is optimized for our C compiler
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#define VpgOfVa(va) ((((WORD)((BYTE)(va>>16)))<<4)|\
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(((BYTE)(((WORD)va)>>8))>>4))
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#define OfsOfVa(va) ((WORD)((va) & 0x07ff))
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#define VaBaseOfVpg(vpg) (((DWORD)(vpg)) << 12)
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// phsyical page header
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typedef struct _pg {
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BYTE fDirty; // needs to be written out
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BYTE cLocks; // this page is locked
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VPG vpg; // what is the virtual page number of this page
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struct _pg FAR *lppgNext; // LRU ordering next
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struct _pg FAR *lppgPrev; // and prev
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} PG;
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typedef PG FAR * LPPG;
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typedef struct _mem {
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VA vaFree;
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WORD cbFree;
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VA mpCbVa[C_FREE_LIST_MAX];
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#ifdef SWAP_INFO
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WORD cPages;
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#endif
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} MGI; // Memory Group Info
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static MGI mpGrpMgi[GRP_MAX];
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// translation table -- map virtual page number to physical page address
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static LPPG mpVpgLppg[C_PAGES_MAX];
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// head and tail pointers for LRU
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//
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static LPPG near lppgHead;
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static LPPG near lppgTail;
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// nil page pointer
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//
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#define lppgNil 0
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// points to the start of linked lists of free blocks
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//
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static VA mpCbVa[C_FREE_LIST_MAX];
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// these pages are locked in memory
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//
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static LPPG near rgLppgLocked[C_LOCKS_MAX];
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// number of pages we have given out
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static VPG near vpgMac;
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// number of physical pages we have resident
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static WORD near cPages;
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// should we keep trying to allocate memory
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static BOOL near fTryMemory = TRUE;
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// the file handle for the backing store
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static int near fhVM;
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// the name of the file for the backing store
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static LSZ near lszVM;
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#ifdef ASSERT
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#define Assert(x, sz) { if (!(x)) AssertionFailed(sz); }
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VOID
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AssertionFailed(LSZ lsz)
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// something went wrong...
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//
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{
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printf("assertion failure:%s\n", lsz);
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Fatal();
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}
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#else
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#define Assert(x, y)
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#endif
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LPV VM_API
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LpvAllocCb(ULONG cb)
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// allocate a block of far memory, if _fmalloc fails, the free some of
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// the memory we were using for the VM cache
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//
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{
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LPV lpv;
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if (!(lpv = calloc(cb,1))) {
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Error(ERR_OUT_OF_MEMORY, "");
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}
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return lpv;
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}
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VA VM_API
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VaAllocGrpCb(WORD grp, ULONG cb)
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// allocate cb bytes from the requested memory group
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//
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{
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VA vaNew;
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MGI FAR *lpMgi;
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LPV lpv;
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lpMgi = &mpGrpMgi[grp];
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Assert(grp < GRP_MAX, "Memory Group out of range");
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if (cb < C_FREE_LIST_MAX && (vaNew = lpMgi->mpCbVa[cb])) {
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lpv = LpvFromVa(vaNew, 0);
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lpMgi->mpCbVa[cb] = *(LPVA)lpv;
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memset(lpv, 0, cb);
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DirtyVa(vaNew);
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return vaNew;
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}
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if (cb < mpGrpMgi[grp].cbFree) {
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vaNew = mpGrpMgi[grp].vaFree;
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(PBYTE)mpGrpMgi[grp].vaFree += cb;
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mpGrpMgi[grp].cbFree -= cb;
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}
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else {
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vaNew = VaAllocCb(CB_PAGE_SIZE - sizeof(PG));
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mpGrpMgi[grp].vaFree = (PBYTE)vaNew + cb;
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mpGrpMgi[grp].cbFree = CB_PAGE_SIZE - cb - sizeof(PG);
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}
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return vaNew;
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}
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VOID VM_API
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FreeGrpVa(WORD grp, VA va, ULONG cb)
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// put this block on the free list for blocks of that size
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// we don't remember how big the blocks were so the caller has
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// provide that info
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//
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{
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MGI FAR *lpMgi;
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lpMgi = &mpGrpMgi[grp];
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if (cb < C_FREE_LIST_MAX && cb >= 4 ) {
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*(LPVA)LpvFromVa(va, 0) = lpMgi->mpCbVa[cb];
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DirtyVa(va);
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lpMgi->mpCbVa[cb] = va;
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}
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}
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