376 lines
12 KiB
C
376 lines
12 KiB
C
//*****************************************************************************
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//
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// MESSAGE HEAP 16 -
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//
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// Heap allocation functions for 32-16 message thunks.
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//
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// NOTE: these are NOT general purpose heap managment routines.
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//
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//
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// 07-17-92 NanduriR Created.
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//
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//*****************************************************************************
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#include "precomp.h"
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#pragma hdrstop
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MODNAME(walloc16.c);
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//*****************************************************************************
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// General Notes:
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//
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// This heap maanger is for specific 'performance gains' and is thus not
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// intended for general purpose use and therfore much of the overhead has
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// been eliminated.
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//
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// This heap manager is intended mainly for thunks - where we are sure that
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// an alloced block will definitely be freed. Thus it is meant for our use.
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//
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// The heap is conceptually an array of constant-size blocks. The size of the
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// block is predefined. The code is optimized for allocation requests of one
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// blocksize or less. It is slower if the allocation request needs more than
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// one block.
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//
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// The heap header is a static array. The header has two flags. One to note
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// that a particular heapblock is in use and the other to note whether the
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// block forms a part of a linked/chained set of contiguous blocks. The blocks
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// are linked when the allocation request is for more than the predefined
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// block size.
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//
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//*****************************************************************************
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#define HEAP16_TOTALSIZE 0x2000
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#define HEAP16_BLOCKSIZE 0x100 // We should set it to an optimum value
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#define HEAP16_BLOCKCOUNT (HEAP16_TOTALSIZE/HEAP16_BLOCKSIZE)
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#define HHDR16_FINUSE 0x01
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#define HHDR16_FLINKED 0x02
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#define ISBLOCKINUSE(block) ((block) & HHDR16_FINUSE)
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#define ISBLOCKLINKED(block) ((block) & HHDR16_FLINKED)
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//*****************************************************************************
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//
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// Globals -
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//
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// vahdr - is the heap header. This header is 32bit memory and not part of the
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// 16bit heap - this is so that the 16bit heap is put to maximum use.
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//
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// vpHeap16 - far pointer to the start of 16bit heap
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//
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// viFreeIndex - the index from which we start searching for a freeblock.
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// Normally this is set to the memoryblock that was most
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// recently freed, thus increasing the chances of finding
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// a freeblock instantly.
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//*****************************************************************************
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BYTE vahdr[HEAP16_BLOCKCOUNT];
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LPBYTE vpHeap16 = (LPBYTE)NULL;
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UINT viFreeIndex = 0; // First look for Free block here.
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//*****************************************************************************
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//
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// malloc16 -
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//
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// Allocs memory from 16bit block.
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// If heap is full, does normal GlobalAlloc
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//
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// Returns farpointer to memoryblock;
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//
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//*****************************************************************************
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VPVOID FASTCALL malloc16(UINT cb)
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{
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INT i, j;
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INT cBlocksRequired;
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INT fContiguousFreeBlocks;
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INT vpT;
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if (vpHeap16 == (LPBYTE)NULL) {
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vpHeap16 = (LPBYTE)GlobalAllocLock16(GMEM_MOVEABLE | GMEM_SHARE, HEAP16_TOTALSIZE,
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NULL);
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if (vpHeap16 != NULL) {
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//
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// Initialize heap header.
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// LATER: is this necessary?. Heaphdr is a static array so
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// is it already intialized to ZERO?
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//
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for(i = 0; i < HEAP16_BLOCKCOUNT ; i++) {
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vahdr[i] = 0;
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}
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}
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}
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if (vpHeap16 != (LPBYTE)NULL) {
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if (cb <= HEAP16_BLOCKSIZE && !ISBLOCKINUSE(vahdr[viFreeIndex])) {
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//
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// If 'single' block and the 'current' index is free.
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//
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vahdr[viFreeIndex] = HHDR16_FINUSE;
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i = viFreeIndex++;
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if (viFreeIndex == HEAP16_BLOCKCOUNT)
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viFreeIndex = 0;
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return (VPVOID)((LPBYTE)vpHeap16 + i * HEAP16_BLOCKSIZE);
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}
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else {
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//
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// if the 'current' index is not free or if 'multiple' blocks
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//
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cBlocksRequired = (cb / HEAP16_BLOCKSIZE) + 1;
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for (i = 0; i < HEAP16_BLOCKCOUNT ; i++ ) {
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if ((viFreeIndex + i + cBlocksRequired) <=
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HEAP16_BLOCKCOUNT) {
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fContiguousFreeBlocks = TRUE;
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for (j = 0; j < cBlocksRequired; j++) {
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if (ISBLOCKINUSE(vahdr[viFreeIndex + i + j])) {
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fContiguousFreeBlocks = FALSE;
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i += j;
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break;
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}
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}
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if (fContiguousFreeBlocks) {
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for (j = 0; j < (cBlocksRequired - 1); j++) {
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vahdr[viFreeIndex + i + j] =
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(HHDR16_FINUSE | HHDR16_FLINKED);
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}
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vahdr[viFreeIndex + i + j] = HHDR16_FINUSE;
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i += viFreeIndex;
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viFreeIndex = i + cBlocksRequired;
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if (viFreeIndex == HEAP16_BLOCKCOUNT)
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viFreeIndex = 0;
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return (VPVOID)((LPBYTE)vpHeap16 + i * HEAP16_BLOCKSIZE);
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}
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}
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else {
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//
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// Outside the heaphdr range. Reset viFreeIndex, so that
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// we search from the start of heaphdr.
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//
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viFreeIndex = -(i+1);
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}
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}
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viFreeIndex = 0;
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}
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}
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//
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// Here - if allocation from heap failed
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//
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vpT = (VPVOID)GlobalAllocLock16(GMEM_MOVEABLE, cb, NULL);
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if (vpT) {
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return vpT;
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}
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else {
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LOGDEBUG(0,("malloc16: failed\n"));
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return (VPVOID)NULL;
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}
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}
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//*****************************************************************************
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//
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// free16 -
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//
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// frees 16bit memory block.
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// If the block is not part of the 16bit heap, does GlobalFree.
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//
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// Returns TRUE;
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//
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//*****************************************************************************
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BOOL FASTCALL free16(VPVOID vp)
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{
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INT iStartIndex;
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BOOL fLinked;
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iStartIndex = ((LPBYTE)vp - (LPBYTE)vpHeap16) / HEAP16_BLOCKSIZE;
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//
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// Invalid iStartIndex implies that the block was GlobalAlloced
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//
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if (iStartIndex >= 0 && iStartIndex < HEAP16_BLOCKCOUNT) {
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//
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// If 'single' block: get out fast
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// else 'multiple' block: loop for all the blocks
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//
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viFreeIndex = iStartIndex;
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if (!ISBLOCKLINKED(vahdr[iStartIndex])) {
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WOW32ASSERT(ISBLOCKINUSE(vahdr[iStartIndex]));
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vahdr[iStartIndex] = 0;
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}
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else {
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while (ISBLOCKINUSE(vahdr[iStartIndex])) {
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fLinked = ISBLOCKLINKED(vahdr[iStartIndex]);
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vahdr[iStartIndex] = 0;
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if (fLinked)
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iStartIndex++;
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else
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break;
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}
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}
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}
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else {
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WOW32ASSERT(LOWORD(vp)==0); // GlobalAlloced pointers have offset = 0
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GlobalUnlockFree16(vp);
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}
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return (BOOL)TRUE;
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}
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//*****************************************************************************
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//
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// stackalloc16 -
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//
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// Allocs memory from current task's 16bit stack.
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// Returns farpointer to memoryblock;
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//
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// NOTES!!!!!:
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// - This is not intended to be a full blown memory manager. It is intended to
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// replace the TDF_INITCALLBACKSTACKFLAG to avoid problems with ptd->vpCBStack
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// getting hosed by multiple stackalloc16 calls. (See bug #393267 et al)
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// - All calls to stackalloc16() and stackfree16() must be properly nested.
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// If you can't assure that your usage is properly nested, you'd better use
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// GlobalAllocLock16() & GlobalUnlockFree16() instead.
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// Beware individual message thunks may have calls to stackalloc16() that
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// aren't readily apparent.
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// - The request size passed to stackfree16() needs to be the same as the size
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// of the corresponding stackalloc16() call.
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// - Run your changes involving stackalloc16() under debug WOW32.DLL. The
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// built-in sanity checking will help you catch any gotcha's
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// - ptd->vpCBStack *SHOULD NOT* be referenced or used outside of stackalloc16()
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// stackfree16(), and callback16().
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// - If this mechanism gets out of whack, chances are the symptom will be
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// a 16-bit stack fault message.
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//*****************************************************************************
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VPVOID FASTCALL stackalloc16(UINT cb)
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{
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#ifdef DEBUG
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VPVOID vp;
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DWORD *psig, cb16;
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#endif
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register PTD ptd;
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// get current task's 16bit stack
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ptd = CURRENTPTD();
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#ifdef DEBUG
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// Save requested allocation size. Assume it will always be less than 64K
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cb16 = (DWORD)cb;
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// Add a dword (for signature) to the requested size
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cb += sizeof(DWORD);
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// Get the current callback sp
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if (ptd->cStackAlloc16 == 0) {
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vp = ptd->vpStack;
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} else {
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vp = ptd->vpCBStack;
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}
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#endif
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// grow ss:sp and return this imaginary pointer.
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if (ptd->cStackAlloc16 == 0) {
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ptd->vpCBStack = ptd->vpStack - cb;
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}
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else {
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ptd->vpCBStack -= cb;
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}
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#ifdef DEBUG
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// Slide our DWORD signature in after the allocated request
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vp -= sizeof(DWORD);
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GETVDMPTR(vp, sizeof(DWORD), psig);
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// The signature hiword is the offset (sp) we're returning.
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// The signature loword is the requested size.
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*psig = ((ptd->vpCBStack & 0x0000FFFF) << 16) | cb16;
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FLUSHVDMPTR(vp, sizeof(DWORD), psig);
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FREEVDMPTR(psig);
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#endif
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ptd->cStackAlloc16++;
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WOW32ASSERT((ptd->cStackAlloc16 >= 1));
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return (VPVOID)ptd->vpCBStack;
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}
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//*****************************************************************************
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//
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// StackFree16 -
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//
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// Decrements count of memory alloc'd by stackalloc16
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//
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// NOTES:
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// - This is #define'd as stackfree16(vp,cb) StackFree16(cb) in free builds
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// and stackfree16(vp,cb) StackFree16(vp, cb) in DEBUG builds (wcall16.h)
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// - See stackalloc16() NOTES above
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//
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//*****************************************************************************
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#ifdef DEBUG
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VOID FASTCALL StackFree16(VPVOID vp, UINT cb)
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#else
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VOID FASTCALL StackFree16(UINT cb)
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#endif
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{
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register PTD ptd;
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#ifdef DEBUG
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DWORD *psig, sig;
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// reconstruct what our signature should be
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sig = ((vp & 0x0000FFFFF) << 16) | cb;
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#endif
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ptd = CURRENTPTD();
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ptd->vpCBStack += cb;
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#ifdef DEBUG
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// vpCBStack should now be pointing at our signature.
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GETVDMPTR(ptd->vpCBStack, sizeof(DWORD), psig);
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// you are hitting this assertion for one of the following reasons:
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// - calls to stackalloc16() & stackfree16() are not properly nested
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// - the signature got overwritten
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// - somebody changed ptd->vpCBStack incorrectly
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WOW32ASSERTMSG((*psig == sig), ("WOW::StackFree16 out of synch!!\n"));
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// adjust for the signature DWORD we added to the request
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ptd->vpCBStack += sizeof(DWORD);
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#endif
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if(ptd->cStackAlloc16 > 0) {
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ptd->cStackAlloc16--;
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} else {
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WOW32ASSERTMSG((FALSE), ("WOW::StackFree16:cStackAlloc16 <= 0!\n"));
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ptd->cStackAlloc16 = 0; // if it was less than 0 somehow
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}
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}
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