SQLite

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** Memory allocation functions used throughout sqlite.
**
** $Id: malloc.c,v 1.32 2008/07/31 17:16:05 drh Exp $
*/
#include "sqliteInt.h"
#include <stdarg.h>
#include <ctype.h>

/*
** This routine runs when the memory allocator sees that the

  memset(&mem0, 0, sizeof(mem0));
  if( sqlite3Config.bCoreMutex ){
    mem0.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM);
  }
  if( sqlite3Config.pScratch && sqlite3Config.szScratch>=3000
      && sqlite3Config.nScratch>0 ){
    int i;
    sqlite3Config.szScratch -= 4;
    mem0.aScratchFree = (u32*)&((char*)sqlite3Config.pScratch)
                  [sqlite3Config.szScratch*sqlite3Config.nScratch];
    for(i=0; i<sqlite3Config.nScratch; i++){ mem0.aScratchFree[i] = i; }
    mem0.nScratchFree = sqlite3Config.nScratch;
  }else{
    sqlite3Config.pScratch = 0;
    sqlite3Config.szScratch = 0;
  }
  if( sqlite3Config.pPage && sqlite3Config.szPage>=512
      && sqlite3Config.nPage>1 ){
    int i;
    int overhead;
    int sz = sqlite3Config.szPage;
    int n = sqlite3Config.nPage;
    overhead = (4*n + sz - 1)/sz;
    sqlite3Config.nPage -= overhead;
    mem0.aPageFree = (u32*)&((char*)sqlite3Config.pPage)
                  [sqlite3Config.szPage*sqlite3Config.nPage];
    for(i=0; i<sqlite3Config.nPage; i++){ mem0.aPageFree[i] = i; }
    mem0.nPageFree = sqlite3Config.nPage;
  }else{
    sqlite3Config.pPage = 0;
    sqlite3Config.szPage = 0;

** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
** @(#) $Id: sqlite.h.in,v 1.384 2008/07/31 17:16:05 drh Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.

** boolean, which enables or disables the collection of memory allocation 
** statistics. When disabled, the following SQLite interfaces become 
** non-operational:
**   <ul>
**   <li> [sqlite3_memory_used()]
**   <li> [sqlite3_memory_highwater()]
**   <li> [sqlite3_soft_heap_limit()]
**   <li> [sqlite3_status()]
**   </ul>
** </dd>
**
** <dt>SQLITE_CONFIG_SCRATCH</dt>
** <dd>This option specifies a static memory buffer that SQLite can use for
** scratch memory.  There are three arguments:  A pointer to the memory, the
** size of each scratch buffer (sz), and the number of buffers (N).  The sz
** argument must be a multiple of 16. The sz parameter should be a few bytes
** larger than the actual scratch space required due internal overhead.
** The first
** argument should point to an allocation of at least sz*N bytes of memory.
** SQLite will use no more than one scratch buffer at once per thread, so
** N should be set to the expected maximum number of threads.  The sz
** parameter should be 6 times the size of the largest database page size.
** Scratch buffers are used as part of the btree balance operation.  If
** The btree balancer needs additional memory beyond what is provided by
** scratch buffers or if no scratch buffer space is specified, then SQLite
** goes to [sqlite3_malloc()] to obtain the memory it needs.</dd>
**
** <dt>SQLITE_CONFIG_PAGECACHE</dt>
** <dd>This option specifies a static memory buffer that SQLite can use for
** the database page cache.  There are three arguments: A pointer to the
** memory, the size of each page buffer (sz), and the number of pages (N).
** The sz argument must be a power of two between 512 and 32768.  The first
** argument should point to an allocation of at least sz*N bytes of memory.
** SQLite will use the memory provided by the first argument to satisfy its
** memory needs for the first N pages that it adds to cache.  If additional
** page cache memory is needed beyond what is provided by this option, then
** SQLite goes to [sqlite3_malloc()] for the additional storage space.
** The implementation might use one or more of the N buffers to hold 
** memory accounting information. </dd>
**
** <dt>SQLITE_CONFIG_HEAP</dt>
** <dd>This option specifies a static memory buffer that SQLite will use
** for all of its dynamic memory allocation needs beyond those provided
** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
** There are three arguments: A pointer to the memory, the number of
** bytes in the memory buffer, and the minimum allocation size.  If

** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their
** internal equivalents).  The value of interest is return in the
** *pHighwater parameter to [sqlite3_status()].  The value written
** into the *pCurrent parameter is undefined.</dd>
**
** <dt>SQLITE_STATUS_PARSER_STACK</dt>
** <dd>This parameter records the deepest parser stack.  It is only
** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>
** </dl>
**
** New status parameters may be added from time to time.
*/
#define SQLITE_STATUS_MEMORY_USED          0
#define SQLITE_STATUS_PAGECACHE_USED       1
#define SQLITE_STATUS_PAGECACHE_OVERFLOW   2

**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains code used to implement test interfaces to the
** memory allocation subsystem.
**
** $Id: test_malloc.c,v 1.44 2008/07/31 17:16:05 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>

  if( Tcl_GetIntFromObj(interp, objv[1], &sz) ) return TCL_ERROR;
  if( Tcl_GetIntFromObj(interp, objv[2], &N) ) return TCL_ERROR;
  free(buf);
  if( sz<0 ){
    buf = 0;
    rc = sqlite3_config(SQLITE_CONFIG_SCRATCH, 0, 0, 0);
  }else{
    buf = malloc( sz*N );
    rc = sqlite3_config(SQLITE_CONFIG_SCRATCH, buf, sz, N);
  }
  pResult = Tcl_NewObj();
  Tcl_ListObjAppendElement(0, pResult, Tcl_NewIntObj(rc));
  Tcl_ListObjAppendElement(0, pResult, Tcl_NewIntObj(N));
  Tcl_SetObjResult(interp, pResult);
  return TCL_OK;

  if( Tcl_GetIntFromObj(interp, objv[1], &sz) ) return TCL_ERROR;
  if( Tcl_GetIntFromObj(interp, objv[2], &N) ) return TCL_ERROR;
  free(buf);
  if( sz<0 ){
    buf = 0;
    rc = sqlite3_config(SQLITE_CONFIG_PAGECACHE, 0, 0, 0);
  }else{
    buf = malloc( sz*N );
    rc = sqlite3_config(SQLITE_CONFIG_PAGECACHE, buf, sz, N);
  }
  pResult = Tcl_NewObj();
  Tcl_ListObjAppendElement(0, pResult, Tcl_NewIntObj(rc));
  Tcl_ListObjAppendElement(0, pResult, Tcl_NewIntObj(N));
  Tcl_SetObjResult(interp, pResult);
  return TCL_OK;