AryaWu/sqlite

1/*2** 2008 September 13**4** The author disclaims copyright to this source code.  In place of5** a legal notice, here is a blessing:6**7**    May you do good and not evil.8**    May you find forgiveness for yourself and forgive others.9**    May you share freely, never taking more than you give.10**11*************************************************************************12**13** The code in this file contains sample implementations of the 14** sqlite3_wsd_init() and sqlite3_wsd_find() functions required if the15** SQLITE_OMIT_WSD symbol is defined at build time.16*/17 18#if defined(SQLITE_OMIT_WSD) && defined(SQLITE_TEST)19 20#include "sqliteInt.h"21 22#define PLS_HASHSIZE 4323 24typedef struct ProcessLocalStorage ProcessLocalStorage;25typedef struct ProcessLocalVar ProcessLocalVar;26 27struct ProcessLocalStorage {28  ProcessLocalVar *aData[PLS_HASHSIZE];29  int nFree;30  u8 *pFree;31};32 33struct ProcessLocalVar {34  void *pKey;35  ProcessLocalVar *pNext;36};37 38static ProcessLocalStorage *pGlobal = 0;39 40int sqlite3_wsd_init(int N, int J){41  if( !pGlobal ){42    int nMalloc = N + sizeof(ProcessLocalStorage) + J*sizeof(ProcessLocalVar);43    pGlobal = (ProcessLocalStorage *)malloc(nMalloc);44    if( pGlobal ){45      memset(pGlobal, 0, sizeof(ProcessLocalStorage));46      pGlobal->nFree = nMalloc - sizeof(ProcessLocalStorage);47      pGlobal->pFree = (u8 *)&pGlobal[1];48    }49  }50 51  return pGlobal ? SQLITE_OK : SQLITE_NOMEM;52}53 54void *sqlite3_wsd_find(void *K, int L){55  int i;56  int iHash = 0;57  ProcessLocalVar *pVar;58 59  /* Calculate a hash of K */60  for(i=0; i<sizeof(void*); i++){61    iHash = (iHash<<3) + ((unsigned char *)&K)[i];62  }63  iHash = iHash%PLS_HASHSIZE;64 65  /* Search the hash table for K. */66  for(pVar=pGlobal->aData[iHash]; pVar && pVar->pKey!=K; pVar=pVar->pNext);67 68  /* If no entry for K was found, create and populate a new one. */69  if( !pVar ){70    int nByte = ROUND8(sizeof(ProcessLocalVar) + L);71    assert( pGlobal->nFree>=nByte );72    pVar = (ProcessLocalVar *)pGlobal->pFree;73    pVar->pKey = K;74    pVar->pNext = pGlobal->aData[iHash];75    pGlobal->aData[iHash] = pVar;76    pGlobal->nFree -= nByte;77    pGlobal->pFree += nByte;78    memcpy(&pVar[1], K, L);79  }80 81  return (void *)&pVar[1];82}83 84#endif85