191 lines
5.1 KiB
C
191 lines
5.1 KiB
C
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/*****************************************************************************
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* *
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* BTKTLONG.C *
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* *
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* Copyright (C) Microsoft Corporation 1989 - 1994. *
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* All Rights reserved. *
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* *
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******************************************************************************
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* *
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* Module Intent *
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* *
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* Functions for LONG keys. *
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* *
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******************************************************************************
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* *
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* Current Owner: BinhN *
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* *
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*****************************************************************************/
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static char s_aszModule[] = __FILE__; /* For error report */
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#include <mvopsys.h>
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#include <orkin.h>
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#include <iterror.h>
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#include <misc.h>
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#include <wrapstor.h>
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#include <_mvutil.h>
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/***************************************************************************
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*
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* @doc INTERNAL
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*
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* @func BK FAR PASCAL | BkScanLInternal |
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* Scan an internal node for a LONG key and return child BK.
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*
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* @parm BK | bk |
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* BK of internal node to scan
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*
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* @parm KEY | key |
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* key to search for
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*
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* @parm SHORT | wLevel |
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* level of btree bk lives on
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*
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* @parm QBTHR | qbthr |
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* btree header containing cache, and btree specs
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*
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* @rdesc bk of subtree that might contain key; bkNil on error
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* args OUT: qbthr->qCache - bk's block will be cached
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*
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* Side Effects: bk's block will be cached
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*
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* @comm Method: Should use binary search. Doesn't, yet.
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*
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***************************************************************************/
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PUBLIC BK FAR PASCAL BkScanLInternal(BK bk, KEY key, SHORT wLevel,
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QBTHR qbthr, QW qiKey, PHRESULT phr)
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{
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QCB qcb;
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QB q;
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SHORT cKeys;
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LONG dwKeyVal;
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dwKeyVal = *(LONG FAR *)key;
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if ((qcb = QFromBk(bk, wLevel, qbthr, phr)) == NULL)
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{
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return bkNil;
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}
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q = qcb->db.rgbBlock;
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cKeys = qcb->db.cKeys;
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bk = SWAPLONG(*(LPUL)q);
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q += sizeof(BK);
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while (cKeys-- > 0)
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{
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if (dwKeyVal >= (LONG) SWAPLONG(*(LPUL)q))
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{
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q += sizeof(LONG);
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bk = SWAPLONG(*(LPUL)q);
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q += sizeof(BK);
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}
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else
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break;
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}
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if (qiKey != NULL)
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{
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*qiKey = (WORD)(q - (QB)qcb->db.rgbBlock);
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}
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return bk;
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}
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/***************************************************************************
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*
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* @doc INTERNAL
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*
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* @func HRESULT FAR PASCAL | RcScanLLeaf |
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* Scan a leaf node for a key and copy the associated data.
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*
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* @parm BK | bk |
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* the leaf block
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*
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* @parm KEY | key |
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* the key we're looking for
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*
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* @parm SHORT | wLevel |
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* the level of leaves (unnecessary)
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*
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* @parm QBTHR | qbthr |
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* the btree header
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*
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* @rdesc ERR_SUCCESS if found; ERR_NOTEXIST if not found
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* args OUT: qRec - if found, record gets copied into this buffer
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* qbtpos - pos of first key >= key goes here
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*
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* @comm If we are scanning for a key greater than any key in this
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* block, the pos returned will be invalid and will point just
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* past the last valid key in this block.
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*
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* Method: Should use binary search if fixed record size. Doesn't, yet.
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*
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***************************************************************************/
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PUBLIC HRESULT FAR PASCAL RcScanLLeaf(BK bk, KEY key, SHORT wLevel,
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QBTHR qbthr, QV qRec, QBTPOS qbtpos)
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{
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QCB qcb;
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QB qb;
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SHORT cKey;
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HRESULT rc;
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LONG dwKeyVal;
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HRESULT errb;
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dwKeyVal = *(LONG FAR *)key;
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if ((qcb = QFromBk(bk, wLevel, qbthr, &errb)) == NULL)
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{
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return (errb);
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}
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rc = E_NOTEXIST;
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qb = qcb->db.rgbBlock + 2 * sizeof(BK);
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for (cKey = 0; cKey < qcb->db.cKeys; cKey++)
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{
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LONG dwVal = (LONG)GETLONG ((LPUL)qb);
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if (dwKeyVal > dwVal)
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{
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// still looking for key
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qb += sizeof(LONG);
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qb += CbSizeRec(qb, qbthr);
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}
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else if (dwKeyVal < dwVal)
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{
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// key not found
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break;
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}
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else
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{
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// matched the key
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if (qRec != NULL)
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{
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qb += sizeof(LONG);
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QVCOPY(qRec, qb, (LONG)CbSizeRec(qb, qbthr));
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}
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rc = S_OK;
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break;
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}
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}
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if (qbtpos != NULL)
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{
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qbtpos->bk = bk;
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qbtpos->iKey = (WORD)(qb - (QB)qcb->db.rgbBlock);
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qbtpos->cKey = cKey;
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}
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return rc;
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}
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/* EOF */
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