SQLite

TCCX = $(TCC) $(OPTS) -I. -I$(TOP)/src

# Object files for the SQLite library.
#
LIBOBJ+= alter.o analyze.o attach.o auth.o btmutex.o btree.o build.o \
         callback.o complete.o date.o delete.o \
         expr.o fault.o func.o hash.o insert.o journal.o loadext.o \
         main.o malloc.o mem1.o mem2.o mem3.o mem4.o mutex.o mutex_os2.o \
         mutex_unix.o mutex_w32.o \
         main.o malloc.o mem1.o mem2.o mem3.o mem4.o mem5.o \
         mutex.o mutex_os2.o mutex_unix.o mutex_w32.o \
         opcodes.o os.o os_os2.o os_unix.o os_win.o \
         pager.o parse.o pragma.o prepare.o printf.o random.o \
         select.o table.o $(TCLOBJ) tokenize.o trigger.o \
         update.o util.o vacuum.o \
         vdbe.o vdbeapi.o vdbeaux.o vdbeblob.o vdbefifo.o vdbemem.o \
         where.o utf.o legacy.o vtab.o

  $(TOP)/src/loadext.c \
  $(TOP)/src/main.c \
  $(TOP)/src/malloc.c \
  $(TOP)/src/mem1.c \
  $(TOP)/src/mem2.c \
  $(TOP)/src/mem3.c \
  $(TOP)/src/mem4.c \
  $(TOP)/src/mem5.c \
  $(TOP)/src/mutex.c \
  $(TOP)/src/mutex.h \
  $(TOP)/src/mutex_os2.c \
  $(TOP)/src/mutex_unix.c \
  $(TOP)/src/mutex_w32.c \
  $(TOP)/src/os.c \
  $(TOP)/src/os.h \

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement a memory
** allocation subsystem for use by SQLite.  
**
** $Id: mem1.c,v 1.15 2008/02/13 18:25:27 danielk1977 Exp $
** $Id: mem1.c,v 1.16 2008/02/14 23:26:56 drh Exp $
*/
#include "sqliteInt.h"

/*
** This version of the memory allocator is the default.  It is
** used when no other memory allocator is specified using compile-time
** macros.
*/
#if !defined(SQLITE_MEMDEBUG) && !defined(SQLITE_MEMORY_SIZE) \
     && !defined(SQLITE_MMAP_HEAP_SIZE)

#ifdef SQLITE_SYSTEM_MALLOC
/*
** We will eventually construct multiple memory allocation subsystems
** suitable for use in various contexts:
**
**    *  Normal multi-threaded builds
**    *  Normal single-threaded builds
**    *  Debugging builds
**
** This initial version is suitable for use in normal multi-threaded
** builds.  We envision that alternative versions will be stored in
** separate source files.  #ifdefs will be used to select the code from
** one of the various memN.c source files for use in any given build.
*/
#include "sqliteInt.h"

/*
** All of the static variables used by this module are collected
** into a single structure named "mem".  This is to keep the
** static variables organized and to reduce namespace pollution
** when this module is combined with other in the amalgamation.
*/

      mem.mxUsed = mem.nowUsed;
    }
  }
  sqlite3_mutex_leave(mem.mutex);
  return (void*)p;
}

#endif /* !SQLITE_MEMDEBUG && !SQLITE_OMIT_MEMORY_ALLOCATION */
#endif /* SQLITE_SYSTEM_MALLOC */

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement a memory
** allocation subsystem for use by SQLite.  
**
** $Id: mem2.c,v 1.20 2008/02/13 18:25:27 danielk1977 Exp $
** $Id: mem2.c,v 1.21 2008/02/14 23:26:56 drh Exp $
*/
#include "sqliteInt.h"

/*
** This version of the memory allocator is used only if the
** SQLITE_MEMDEBUG macro is defined and SQLITE_OMIT_MEMORY_ALLOCATION
** SQLITE_MEMDEBUG macro is defined
** is not defined.
*/
#if defined(SQLITE_MEMDEBUG)
#ifdef SQLITE_MEMDEBUG

/*
** We will eventually construct multiple memory allocation subsystems
** suitable for use in various contexts:
**
**    *  Normal multi-threaded builds
**    *  Normal single-threaded builds
**    *  Debugging builds
**
** This version is suitable for use in debugging builds.
**
** Features:
**
**    * Every allocate has guards at both ends.
**    * New allocations are initialized with randomness
**    * Allocations are overwritten with randomness when freed
**    * Optional logs of malloc activity generated
**    * Summary of outstanding allocations with backtraces to the
**      point of allocation.
**    * The ability to simulate memory allocation failure
*/
#include "sqliteInt.h"
#include <stdio.h>

/*
** The backtrace functionality is only available with GLIBC
*/
#ifdef __GLIBC__
  extern int backtrace(void**,int);
  extern void backtrace_symbols_fd(void*const*,int,int);
#else
# define backtrace(A,B) 0
# define backtrace_symbols_fd(A,B,C)
#endif
#include <stdio.h>

/*
** Each memory allocation looks like this:
**
**  ------------------------------------------------------------------------
**  | Title |  backtrace pointers |  MemBlockHdr |  allocation |  EndGuard |
**  ------------------------------------------------------------------------

  for(i=0; i<NCSIZE; i++){
    nTotal += mem.sizeCnt[i];
  }
  return nTotal;
}


#endif /* SQLITE_MEMDEBUG && !SQLITE_OMIT_MEMORY_ALLOCATION */
#endif /* SQLITE_MEMDEBUG */

** use of malloc().  All dynamically allocatable memory is
** contained in a static array, mem.aPool[].  The size of this
** fixed memory pool is SQLITE_MEMORY_SIZE bytes.
**
** This version of the memory allocation subsystem is used if
** and only if SQLITE_MEMORY_SIZE is defined.
**
** $Id: mem3.c,v 1.10 2008/02/14 15:31:52 danielk1977 Exp $
** $Id: mem3.c,v 1.11 2008/02/14 23:26:56 drh Exp $
*/
#include "sqliteInt.h"

/*
** This version of the memory allocator is used only when 
** SQLITE_MEMORY_SIZE is defined.
*/
#if defined(SQLITE_MEMORY_SIZE)
#include "sqliteInt.h"

#ifdef SQLITE_MEMDEBUG
#ifdef SQLITE_MEMORY_SIZE
# error  cannot define both SQLITE_MEMDEBUG and SQLITE_MEMORY_SIZE
#endif

/*
** Maximum size (in Mem3Blocks) of a "small" chunk.
*/
#define MX_SMALL 10

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement a memory
** allocation subsystem for use by SQLite.  
**
** $Id: mem4.c,v 1.1 2007/11/29 18:36:49 drh Exp $
** $Id: mem4.c,v 1.2 2008/02/14 23:26:56 drh Exp $
*/
#include "sqliteInt.h"

/*
** This version of the memory allocator attempts to obtain memory
** from mmap() if the size of the allocation is close to the size
** of a virtual memory page.  If the size of the allocation is different
** from the virtual memory page size, then ordinary malloc() is used.
** Ordinary malloc is also used if space allocated to mmap() is
** exhausted.
**
** Enable this memory allocation by compiling with -DSQLITE_MMAP_HEAP_SIZE=nnn
** where nnn is the maximum number of bytes of mmap-ed memory you want 
** to support.   This module may choose to use less memory than requested.
**
*/
#if defined(SQLITE_MMAP_HEAP_SIZE)
#ifdef SQLITE_MMAP_HEAP_SIZE

#if defined(SQLITE_MEMDEBUG) || defined(SQLITE_MEMORY_SIZE)
# error cannot use SQLITE_MMAP_HEAP_SIZE with either SQLITE_MEMDEBUG \
        or SQLITE_MEMORY_SIZE
#endif

/*
** This is a test version of the memory allocator that attempts to
** use mmap() and madvise() for allocations and frees of approximately
** the virtual memory page size.
*/
#include <sys/types.h>
#include <sys/mman.h>
#include <errno.h>
#include "sqliteInt.h"
#include <unistd.h>


/*
** All of the static variables used by this module are collected
** into a single structure named "mem".  This is to keep the
** static variables organized and to reduce namespace pollution

    memsys4Free(pPrior);
  }
  assert( mem.mutex!=0 );
  sqlite3_mutex_leave(mem.mutex);
  return (void*)p;
}

#endif /* !SQLITE_MEMDEBUG && !SQLITE_OMIT_MEMORY_ALLOCATION */
#endif /* SQLITE_MMAP_HEAP_SIZE */

/*
** 2007 October 14
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement a memory
** allocation subsystem for use by SQLite. 
**
** This version of the memory allocation subsystem omits all
** use of malloc().  All dynamically allocatable memory is
** contained in a static array, mem.aPool[].  The size of this
** fixed memory pool is SQLITE_POW2_MEMORY_SIZE bytes.
**
** This version of the memory allocation subsystem is used if
** and only if SQLITE_POW2_MEMORY_SIZE is defined.
**
** $Id: mem5.c,v 1.1 2008/02/14 23:26:56 drh Exp $
*/
#include "sqliteInt.h"

/*
** This version of the memory allocator is used only when 
** SQLITE_POW2_MEMORY_SIZE is defined.
*/
#ifdef SQLITE_POW2_MEMORY_SIZE

/*
** Maximum size (in Mem3Blocks) of a "small" chunk.
*/
#define MX_SMALL 10


/*
** Number of freelist hash slots
*/
#define N_HASH  61

/*
** A memory allocation (also called a "chunk") consists of two or 
** more blocks where each block is 8 bytes.  The first 8 bytes are 
** a header that is not returned to the user.
**
** A chunk is two or more blocks that is either checked out or
** free.  The first block has format u.hdr.  u.hdr.size4x is 4 times the
** size of the allocation in blocks if the allocation is free.
** The u.hdr.size4x&1 bit is true if the chunk is checked out and
** false if the chunk is on the freelist.  The u.hdr.size4x&2 bit
** is true if the previous chunk is checked out and false if the
** previous chunk is free.  The u.hdr.prevSize field is the size of
** the previous chunk in blocks if the previous chunk is on the
** freelist. If the previous chunk is checked out, then
** u.hdr.prevSize can be part of the data for that chunk and should
** not be read or written.
**
** We often identify a chunk by its index in mem.aPool[].  When
** this is done, the chunk index refers to the second block of
** the chunk.  In this way, the first chunk has an index of 1.
** A chunk index of 0 means "no such chunk" and is the equivalent
** of a NULL pointer.
**
** The second block of free chunks is of the form u.list.  The
** two fields form a double-linked list of chunks of related sizes.
** Pointers to the head of the list are stored in mem.aiSmall[] 
** for smaller chunks and mem.aiHash[] for larger chunks.
**
** The second block of a chunk is user data if the chunk is checked 
** out.  If a chunk is checked out, the user data may extend into
** the u.hdr.prevSize value of the following chunk.
*/
typedef struct Mem3Block Mem3Block;
struct Mem3Block {
  union {
    struct {
      u32 prevSize;   /* Size of previous chunk in Mem3Block elements */
      u32 size4x;     /* 4x the size of current chunk in Mem3Block elements */
    } hdr;
    struct {
      u32 next;       /* Index in mem.aPool[] of next free chunk */
      u32 prev;       /* Index in mem.aPool[] of previous free chunk */
    } list;
  } u;
};

/*
** All of the static variables used by this module are collected
** into a single structure named "mem".  This is to keep the
** static variables organized and to reduce namespace pollution
** when this module is combined with other in the amalgamation.
*/
static struct {
  /*
  ** True if we are evaluating an out-of-memory callback.
  */
  int alarmBusy;
  
  /*
  ** Mutex to control access to the memory allocation subsystem.
  */
  sqlite3_mutex *mutex;
  
  /*
  ** The minimum amount of free space that we have seen.
  */
  u32 mnMaster;

  /*
  ** iMaster is the index of the master chunk.  Most new allocations
  ** occur off of this chunk.  szMaster is the size (in Mem3Blocks)
  ** of the current master.  iMaster is 0 if there is not master chunk.
  ** The master chunk is not in either the aiHash[] or aiSmall[].
  */
  u32 iMaster;
  u32 szMaster;


u64 totalAlloc;
u64 totalExcess;
int nAlloc;

  /*
  ** Array of lists of free blocks according to the block size 
  ** for smaller chunks, or a hash on the block size for larger
  ** chunks.
  */
  u32 aiSmall[MX_SMALL-1];   /* For sizes 2 through MX_SMALL, inclusive */
  u32 aiHash[N_HASH];        /* For sizes MX_SMALL+1 and larger */

  /*
  ** Memory available for allocation
  */
  Mem3Block aPool[SQLITE_POW2_MEMORY_SIZE/sizeof(Mem3Block)+2];
} mem;

/*
** Unlink the chunk at mem.aPool[i] from list it is currently
** on.  *pRoot is the list that i is a member of.
*/
static void memsys3UnlinkFromList(u32 i, u32 *pRoot){
  u32 next = mem.aPool[i].u.list.next;
  u32 prev = mem.aPool[i].u.list.prev;
  assert( sqlite3_mutex_held(mem.mutex) );
  if( prev==0 ){
    *pRoot = next;
  }else{
    mem.aPool[prev].u.list.next = next;
  }
  if( next ){
    mem.aPool[next].u.list.prev = prev;
  }
  mem.aPool[i].u.list.next = 0;
  mem.aPool[i].u.list.prev = 0;
}

/*
** Unlink the chunk at index i from 
** whatever list is currently a member of.
*/
static void memsys3Unlink(u32 i){
  u32 size, hash;
  assert( sqlite3_mutex_held(mem.mutex) );
  assert( (mem.aPool[i-1].u.hdr.size4x & 1)==0 );
  assert( i>=1 );
  size = mem.aPool[i-1].u.hdr.size4x/4;
  assert( size==mem.aPool[i+size-1].u.hdr.prevSize );
  assert( size>=2 );
  if( size <= MX_SMALL ){
    memsys3UnlinkFromList(i, &mem.aiSmall[size-2]);
  }else{
    hash = size % N_HASH;
    memsys3UnlinkFromList(i, &mem.aiHash[hash]);
  }
}

/*
** Link the chunk at mem.aPool[i] so that is on the list rooted
** at *pRoot.
*/
static void memsys3LinkIntoList(u32 i, u32 *pRoot){
  assert( sqlite3_mutex_held(mem.mutex) );
  mem.aPool[i].u.list.next = *pRoot;
  mem.aPool[i].u.list.prev = 0;
  if( *pRoot ){
    mem.aPool[*pRoot].u.list.prev = i;
  }
  *pRoot = i;
}

/*
** Link the chunk at index i into either the appropriate
** small chunk list, or into the large chunk hash table.
*/
static void memsys3Link(u32 i){
  u32 size, hash;
  assert( sqlite3_mutex_held(mem.mutex) );
  assert( i>=1 );
  assert( (mem.aPool[i-1].u.hdr.size4x & 1)==0 );
  size = mem.aPool[i-1].u.hdr.size4x/4;
  assert( size==mem.aPool[i+size-1].u.hdr.prevSize );
  assert( size>=2 );
  if( size <= MX_SMALL ){
    memsys3LinkIntoList(i, &mem.aiSmall[size-2]);
  }else{
    hash = size % N_HASH;
    memsys3LinkIntoList(i, &mem.aiHash[hash]);
  }
}

/*
** Enter the mutex mem.mutex. Allocate it if it is not already allocated.
**
** Also:  Initialize the memory allocation subsystem the first time
** this routine is called.
*/
static void memsys3Enter(void){
  if( mem.mutex==0 ){
    mem.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MEM);
    mem.aPool[0].u.hdr.size4x = SQLITE_POW2_MEMORY_SIZE/2 + 2;
    mem.aPool[SQLITE_POW2_MEMORY_SIZE/8].u.hdr.prevSize = SQLITE_POW2_MEMORY_SIZE/8;
    mem.aPool[SQLITE_POW2_MEMORY_SIZE/8].u.hdr.size4x = 1;
    mem.iMaster = 1;
    mem.szMaster = SQLITE_POW2_MEMORY_SIZE/8;
    mem.mnMaster = mem.szMaster;
  }
  sqlite3_mutex_enter(mem.mutex);
}

/*
** Return the amount of memory currently checked out.
*/
sqlite3_int64 sqlite3_memory_used(void){
  sqlite3_int64 n;
  memsys3Enter();
  n = SQLITE_POW2_MEMORY_SIZE - mem.szMaster*8;
  sqlite3_mutex_leave(mem.mutex);  
  return n;
}

/*
** Return the maximum amount of memory that has ever been
** checked out since either the beginning of this process
** or since the most recent reset.
*/
sqlite3_int64 sqlite3_memory_highwater(int resetFlag){
  sqlite3_int64 n;
  memsys3Enter();
  n = SQLITE_POW2_MEMORY_SIZE - mem.mnMaster*8;
  if( resetFlag ){
    mem.mnMaster = mem.szMaster;
  }
printf("alloc-cnt=%d avg-size=%lld avg-excess=%lld\n",
mem.nAlloc, mem.totalAlloc/mem.nAlloc, mem.totalExcess/mem.nAlloc);
  sqlite3_mutex_leave(mem.mutex);  
  return n;
}

/*
** Change the alarm callback.
**
** This is a no-op for the static memory allocator.  The purpose
** of the memory alarm is to support sqlite3_soft_heap_limit().
** But with this memory allocator, the soft_heap_limit is really
** a hard limit that is fixed at SQLITE_POW2_MEMORY_SIZE.
*/
int sqlite3_memory_alarm(
  void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
  void *pArg,
  sqlite3_int64 iThreshold
){
  return SQLITE_OK;
}

/*
** Called when we are unable to satisfy an allocation of nBytes.
*/
static void memsys3OutOfMemory(int nByte){
  if( !mem.alarmBusy ){
    mem.alarmBusy = 1;
    assert( sqlite3_mutex_held(mem.mutex) );
    sqlite3_mutex_leave(mem.mutex);
    sqlite3_release_memory(nByte);
    sqlite3_mutex_enter(mem.mutex);
    mem.alarmBusy = 0;
  }
}

/*
** Return the size of an outstanding allocation, in bytes.  The
** size returned omits the 8-byte header overhead.  This only
** works for chunks that are currently checked out.
*/
int sqlite3MallocSize(void *p){
  int iSize = 0;
  if( p ){
    Mem3Block *pBlock = (Mem3Block*)p;
    assert( (pBlock[-1].u.hdr.size4x&1)!=0 );
    iSize = (pBlock[-1].u.hdr.size4x&~3)*2 - 4;
  }
  return iSize;
}

/*
** Chunk i is a free chunk that has been unlinked.  Adjust its 
** size parameters for check-out and return a pointer to the 
** user portion of the chunk.
*/
static void *memsys3Checkout(u32 i, int nBlock){
  u32 x;
  assert( sqlite3_mutex_held(mem.mutex) );
  assert( i>=1 );
  assert( mem.aPool[i-1].u.hdr.size4x/4==nBlock );
  assert( mem.aPool[i+nBlock-1].u.hdr.prevSize==nBlock );
  x = mem.aPool[i-1].u.hdr.size4x;
  mem.aPool[i-1].u.hdr.size4x = nBlock*4 | 1 | (x&2);
  mem.aPool[i+nBlock-1].u.hdr.prevSize = nBlock;
  mem.aPool[i+nBlock-1].u.hdr.size4x |= 2;
  return &mem.aPool[i];
}

/*
** Carve a piece off of the end of the mem.iMaster free chunk.
** Return a pointer to the new allocation.  Or, if the master chunk
** is not large enough, return 0.
*/
static void *memsys3FromMaster(int nBlock){
  assert( sqlite3_mutex_held(mem.mutex) );
  assert( mem.szMaster>=nBlock );
  if( nBlock>=mem.szMaster-1 ){
    /* Use the entire master */
    void *p = memsys3Checkout(mem.iMaster, mem.szMaster);
    mem.iMaster = 0;
    mem.szMaster = 0;
    mem.mnMaster = 0;
    return p;
  }else{
    /* Split the master block.  Return the tail. */
    u32 newi, x;
    newi = mem.iMaster + mem.szMaster - nBlock;
    assert( newi > mem.iMaster+1 );
    mem.aPool[mem.iMaster+mem.szMaster-1].u.hdr.prevSize = nBlock;
    mem.aPool[mem.iMaster+mem.szMaster-1].u.hdr.size4x |= 2;
    mem.aPool[newi-1].u.hdr.size4x = nBlock*4 + 1;
    mem.szMaster -= nBlock;
    mem.aPool[newi-1].u.hdr.prevSize = mem.szMaster;
    x = mem.aPool[mem.iMaster-1].u.hdr.size4x & 2;
    mem.aPool[mem.iMaster-1].u.hdr.size4x = mem.szMaster*4 | x;
    if( mem.szMaster < mem.mnMaster ){
      mem.mnMaster = mem.szMaster;
    }
    return (void*)&mem.aPool[newi];
  }
}

/*
** *pRoot is the head of a list of free chunks of the same size
** or same size hash.  In other words, *pRoot is an entry in either
** mem.aiSmall[] or mem.aiHash[].  
**
** This routine examines all entries on the given list and tries
** to coalesce each entries with adjacent free chunks.  
**
** If it sees a chunk that is larger than mem.iMaster, it replaces 
** the current mem.iMaster with the new larger chunk.  In order for
** this mem.iMaster replacement to work, the master chunk must be
** linked into the hash tables.  That is not the normal state of
** affairs, of course.  The calling routine must link the master
** chunk before invoking this routine, then must unlink the (possibly
** changed) master chunk once this routine has finished.
*/
static void memsys3Merge(u32 *pRoot){
  u32 iNext, prev, size, i, x;

  assert( sqlite3_mutex_held(mem.mutex) );
  for(i=*pRoot; i>0; i=iNext){
    iNext = mem.aPool[i].u.list.next;
    size = mem.aPool[i-1].u.hdr.size4x;
    assert( (size&1)==0 );
    if( (size&2)==0 ){
      memsys3UnlinkFromList(i, pRoot);
      assert( i > mem.aPool[i-1].u.hdr.prevSize );
      prev = i - mem.aPool[i-1].u.hdr.prevSize;
      if( prev==iNext ){
        iNext = mem.aPool[prev].u.list.next;
      }
      memsys3Unlink(prev);
      size = i + size/4 - prev;
      x = mem.aPool[prev-1].u.hdr.size4x & 2;
      mem.aPool[prev-1].u.hdr.size4x = size*4 | x;
      mem.aPool[prev+size-1].u.hdr.prevSize = size;
      memsys3Link(prev);
      i = prev;
    }else{
      size /= 4;
    }
    if( size>mem.szMaster ){
      mem.iMaster = i;
      mem.szMaster = size;
    }
  }
}

/*
** Return a block of memory of at least nBytes in size.
** Return NULL if unable.
*/
static void *memsys3Malloc(int nByte){
  u32 i;
  int nBlock;
  int toFree;
  int x;

  assert( sqlite3_mutex_held(mem.mutex) );
  assert( sizeof(Mem3Block)==8 );
  for(x=256; x<nByte; x *= 2){}
mem.nAlloc++;
mem.totalAlloc += x;
mem.totalExcess += x - nByte;
  nByte = x;
  nBlock = (nByte + 11)/8;
  assert( nBlock >= 2 );

  /* STEP 1:
  ** Look for an entry of the correct size in either the small
  ** chunk table or in the large chunk hash table.  This is
  ** successful most of the time (about 9 times out of 10).
  */
  if( nBlock <= MX_SMALL ){
    i = mem.aiSmall[nBlock-2];
    if( i>0 ){
      memsys3UnlinkFromList(i, &mem.aiSmall[nBlock-2]);
      return memsys3Checkout(i, nBlock);
    }
  }else{
    int hash = nBlock % N_HASH;
    for(i=mem.aiHash[hash]; i>0; i=mem.aPool[i].u.list.next){
      if( mem.aPool[i-1].u.hdr.size4x/4==nBlock ){
        memsys3UnlinkFromList(i, &mem.aiHash[hash]);
        return memsys3Checkout(i, nBlock);
      }
    }
  }

  /* STEP 2:
  ** Try to satisfy the allocation by carving a piece off of the end
  ** of the master chunk.  This step usually works if step 1 fails.
  */
  if( mem.szMaster>=nBlock ){
    return memsys3FromMaster(nBlock);
  }


  /* STEP 3:  
  ** Loop through the entire memory pool.  Coalesce adjacent free
  ** chunks.  Recompute the master chunk as the largest free chunk.
  ** Then try again to satisfy the allocation by carving a piece off
  ** of the end of the master chunk.  This step happens very
  ** rarely (we hope!)
  */
  for(toFree=nBlock*16; toFree<SQLITE_POW2_MEMORY_SIZE*2; toFree *= 2){
    memsys3OutOfMemory(toFree);
    if( mem.iMaster ){
      memsys3Link(mem.iMaster);
      mem.iMaster = 0;
      mem.szMaster = 0;
    }
    for(i=0; i<N_HASH; i++){
      memsys3Merge(&mem.aiHash[i]);
    }
    for(i=0; i<MX_SMALL-1; i++){
      memsys3Merge(&mem.aiSmall[i]);
    }
    if( mem.szMaster ){
      memsys3Unlink(mem.iMaster);
      if( mem.szMaster>=nBlock ){
        return memsys3FromMaster(nBlock);
      }
    }
  }

  /* If none of the above worked, then we fail. */
  return 0;
}

/*
** Free an outstanding memory allocation.
*/
void memsys3Free(void *pOld){
  Mem3Block *p = (Mem3Block*)pOld;
  int i;
  u32 size, x;
  assert( sqlite3_mutex_held(mem.mutex) );
  assert( p>mem.aPool && p<&mem.aPool[SQLITE_POW2_MEMORY_SIZE/8] );
  i = p - mem.aPool;
  assert( (mem.aPool[i-1].u.hdr.size4x&1)==1 );
  size = mem.aPool[i-1].u.hdr.size4x/4;
  assert( i+size<=SQLITE_POW2_MEMORY_SIZE/8+1 );
  mem.aPool[i-1].u.hdr.size4x &= ~1;
  mem.aPool[i+size-1].u.hdr.prevSize = size;
  mem.aPool[i+size-1].u.hdr.size4x &= ~2;
  memsys3Link(i);

  /* Try to expand the master using the newly freed chunk */
  if( mem.iMaster ){
    while( (mem.aPool[mem.iMaster-1].u.hdr.size4x&2)==0 ){
      size = mem.aPool[mem.iMaster-1].u.hdr.prevSize;
      mem.iMaster -= size;
      mem.szMaster += size;
      memsys3Unlink(mem.iMaster);
      x = mem.aPool[mem.iMaster-1].u.hdr.size4x & 2;
      mem.aPool[mem.iMaster-1].u.hdr.size4x = mem.szMaster*4 | x;
      mem.aPool[mem.iMaster+mem.szMaster-1].u.hdr.prevSize = mem.szMaster;
    }
    x = mem.aPool[mem.iMaster-1].u.hdr.size4x & 2;
    while( (mem.aPool[mem.iMaster+mem.szMaster-1].u.hdr.size4x&1)==0 ){
      memsys3Unlink(mem.iMaster+mem.szMaster);
      mem.szMaster += mem.aPool[mem.iMaster+mem.szMaster-1].u.hdr.size4x/4;
      mem.aPool[mem.iMaster-1].u.hdr.size4x = mem.szMaster*4 | x;
      mem.aPool[mem.iMaster+mem.szMaster-1].u.hdr.prevSize = mem.szMaster;
    }
  }
}

/*
** Allocate nBytes of memory
*/
void *sqlite3_malloc(int nBytes){
  sqlite3_int64 *p = 0;
  if( nBytes>0 ){
    memsys3Enter();
    p = memsys3Malloc(nBytes);
    sqlite3_mutex_leave(mem.mutex);
  }
  return (void*)p; 
}

/*
** Free memory.
*/
void sqlite3_free(void *pPrior){
  if( pPrior==0 ){
    return;
  }
  assert( mem.mutex!=0 );
  sqlite3_mutex_enter(mem.mutex);
  memsys3Free(pPrior);
  sqlite3_mutex_leave(mem.mutex);  
}

/*
** Change the size of an existing memory allocation
*/
void *sqlite3_realloc(void *pPrior, int nBytes){
  int nOld;
  void *p;
  if( pPrior==0 ){
    return sqlite3_malloc(nBytes);
  }
  if( nBytes<=0 ){
    sqlite3_free(pPrior);
    return 0;
  }
  assert( mem.mutex!=0 );
  nOld = sqlite3MallocSize(pPrior);
  if( nBytes<=nOld && nBytes>=nOld-128 ){
    return pPrior;
  }
  sqlite3_mutex_enter(mem.mutex);
  p = memsys3Malloc(nBytes);
  if( p ){
    if( nOld<nBytes ){
      memcpy(p, pPrior, nOld);
    }else{
      memcpy(p, pPrior, nBytes);
    }
    memsys3Free(pPrior);
  }
  sqlite3_mutex_leave(mem.mutex);
  return p;
}

/*
** Open the file indicated and write a log of all unfreed memory 
** allocations into that log.
*/
void sqlite3_memdebug_dump(const char *zFilename){
#ifdef SQLITE_DEBUG
  FILE *out;
  int i, j;
  u32 size;
  if( zFilename==0 || zFilename[0]==0 ){
    out = stdout;
  }else{
    out = fopen(zFilename, "w");
    if( out==0 ){
      fprintf(stderr, "** Unable to output memory debug output log: %s **\n",
                      zFilename);
      return;
    }
  }
  memsys3Enter();
  fprintf(out, "CHUNKS:\n");
  for(i=1; i<=SQLITE_POW2_MEMORY_SIZE/8; i+=size/4){
    size = mem.aPool[i-1].u.hdr.size4x;
    if( size/4<=1 ){
      fprintf(out, "%p size error\n", &mem.aPool[i]);
      assert( 0 );
      break;
    }
    if( (size&1)==0 && mem.aPool[i+size/4-1].u.hdr.prevSize!=size/4 ){
      fprintf(out, "%p tail size does not match\n", &mem.aPool[i]);
      assert( 0 );
      break;
    }
    if( ((mem.aPool[i+size/4-1].u.hdr.size4x&2)>>1)!=(size&1) ){
      fprintf(out, "%p tail checkout bit is incorrect\n", &mem.aPool[i]);
      assert( 0 );
      break;
    }
    if( size&1 ){
      fprintf(out, "%p %6d bytes checked out\n", &mem.aPool[i], (size/4)*8-8);
    }else{
      fprintf(out, "%p %6d bytes free%s\n", &mem.aPool[i], (size/4)*8-8,
                  i==mem.iMaster ? " **master**" : "");
    }
  }
  for(i=0; i<MX_SMALL-1; i++){
    if( mem.aiSmall[i]==0 ) continue;
    fprintf(out, "small(%2d):", i);
    for(j = mem.aiSmall[i]; j>0; j=mem.aPool[j].u.list.next){
      fprintf(out, " %p(%d)", &mem.aPool[j],
              (mem.aPool[j-1].u.hdr.size4x/4)*8-8);
    }
    fprintf(out, "\n"); 
  }
  for(i=0; i<N_HASH; i++){
    if( mem.aiHash[i]==0 ) continue;
    fprintf(out, "hash(%2d):", i);
    for(j = mem.aiHash[i]; j>0; j=mem.aPool[j].u.list.next){
      fprintf(out, " %p(%d)", &mem.aPool[j],
              (mem.aPool[j-1].u.hdr.size4x/4)*8-8);
    }
    fprintf(out, "\n"); 
  }
  fprintf(out, "master=%d\n", mem.iMaster);
  fprintf(out, "nowUsed=%d\n", SQLITE_POW2_MEMORY_SIZE - mem.szMaster*8);
  fprintf(out, "mxUsed=%d\n", SQLITE_POW2_MEMORY_SIZE - mem.mnMaster*8);
  sqlite3_mutex_leave(mem.mutex);
  if( out==stdout ){
    fflush(stdout);
  }else{
    fclose(out);
  }
#endif
}


#endif /* !SQLITE_POW2_MEMORY_SIZE */

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.405 2008/02/02 20:47:38 drh Exp $
** @(#) $Id: pager.c,v 1.406 2008/02/14 23:26:56 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include <assert.h>
#include <string.h>

/*

  PgHdr *pPg, *pNext;
  if( pPager->errCode ) return;
  for(pPg=pPager->pAll; pPg; pPg=pNext){
    IOTRACE(("PGFREE %p %d\n", pPager, pPg->pgno));
    PAGER_INCR(sqlite3_pager_pgfree_count);
    pNext = pPg->pNextAll;
    lruListRemove(pPg);
    sqlite3_free(pPg->pData);
    sqlite3_free(pPg);
  }
  assert(pPager->lru.pFirst==0);
  assert(pPager->lru.pFirstSynced==0);
  assert(pPager->lru.pLast==0);
  pPager->pStmt = 0;
  pPager->pAll = 0;

      ppPg = &pPg->pNextAll;
    }else{
      *ppPg = pPg->pNextAll;
      IOTRACE(("PGFREE %p %d\n", pPager, pPg->pgno));
      PAGER_INCR(sqlite3_pager_pgfree_count);
      unlinkPage(pPg);
      makeClean(pPg);
      sqlite3_free(pPg->pData);
      sqlite3_free(pPg);
      pPager->nPage--;
    }
  }
}

/*

      nReleased += (
          sizeof(*pPg) + pPager->pageSize
          + sizeof(u32) + pPager->nExtra
          + MEMDB*sizeof(PgHistory) 
      );
      IOTRACE(("PGFREE %p %d *\n", pPager, pPg->pgno));
      PAGER_INCR(sqlite3_pager_pgfree_count);
      sqlite3_free(pPg->pData);
      sqlite3_free(pPg);
      pPager->nPage--;
    }else{
      /* An error occured whilst writing to the database file or 
      ** journal in pager_recycle(). The error is not returned to the 
      ** caller of this function. Instead, set the Pager.errCode variable.
      ** The error will be returned to the user (or users, in the case 

  /* Create a new PgHdr if any of the four conditions defined 
  ** above are met: */
  if( pPager->nPage<pPager->mxPage
   || pPager->lru.pFirst==0 
   || MEMDB
   || (pPager->lru.pFirstSynced==0 && pPager->doNotSync)
  ){
    void *pData;
    if( pPager->nPage>=pPager->nHash ){
      pager_resize_hash_table(pPager,
         pPager->nHash<256 ? 256 : pPager->nHash*2);
      if( pPager->nHash==0 ){
        rc = SQLITE_NOMEM;
        goto pager_allocate_out;
      }
    }
    pagerLeave(pPager);
    nByteHdr = sizeof(*pPg) + sizeof(u32) + pPager->nExtra
              + MEMDB*sizeof(PgHistory);
    pPg = sqlite3_malloc( nByteHdr + pPager->pageSize );
    pPg = sqlite3_malloc( nByteHdr );
    if( pPg ){
      pData = sqlite3_malloc( pPager->pageSize );
      if( pData==0 ){
        sqlite3_free(pPg);
        pPg = 0;
      }
    }
    pagerEnter(pPager);
    if( pPg==0 ){
      rc = SQLITE_NOMEM;
      goto pager_allocate_out;
    }
    memset(pPg, 0, nByteHdr);
    pPg->pData = (void*)(nByteHdr + (char*)pPg);
    pPg->pData = pData;
    pPg->pPager = pPager;
    pPg->pNextAll = pPager->pAll;
    pPager->pAll = pPg;
    pPager->nPage++;
  }else{
    /* Recycle an existing page with a zero ref-count. */
    rc = pager_recycle(pPager, &pPg);

/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.661 2008/02/13 18:25:27 danielk1977 Exp $
** @(#) $Id: sqliteInt.h,v 1.662 2008/02/14 23:26:56 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** The macro unlikely() is a hint that surrounds a boolean
** expression that is usually false.  Macro likely() surrounds

#if defined(THREADSAFE)
# define SQLITE_THREADSAFE THREADSAFE
#else
# define SQLITE_THREADSAFE 1
#endif
#endif

/*
** Exactly one of the following macros must be defined in order to
** specify which memory allocation subsystem to use.
**
**     SQLITE_SYSTEM_MALLOC          // Use normal system malloc()
**     SQLITE_MEMDEBUG               // Debugging version of system malloc()
**     SQLITE_MEMORY_SIZE            // internal allocator #1
**     SQLITE_MMAP_HEAP_SIZE         // internal mmap() allocator
**     SQLITE_POW2_MEMORY_SIZE       // internal power-of-two allocator
**
** If none of the above are defined, then set SQLITE_SYSTEM_MALLOC as
** the default.
*/
#if defined(SQLITE_SYSTEM_MALLOC)+defined(SQLITE_MEMDEBUG)+\
    defined(SQLITE_MEMORY_SIZE)+defined(SQLITE_MMAP_HEAP_SIZE)+\
    defined(SQLITE_POW2_MEMORY_SIZE)>1
# error "At most one of the following compile-time configuration options\
 is allows: SQLITE_SYSTEM_MALLOC, SQLITE_MEMDEBUG, SQLITE_MEMORY_SIZE,\
 SQLITE_MMAP_HEAP_SIZE, SQLITE_POW2_MEMORY_SIZE"
#endif
#if defined(SQLITE_SYSTEM_MALLOC)+defined(SQLITE_MEMDEBUG)+\
    defined(SQLITE_MEMORY_SIZE)+defined(SQLITE_MMAP_HEAP_SIZE)+\
    defined(SQLITE_POW2_MEMORY_SIZE)==0
# define SQLITE_SYSTEM_MALLOC 1
#endif

/*
** We need to define _XOPEN_SOURCE as follows in order to enable
** recursive mutexes on most unix systems.  But Mac OS X is different.
** The _XOPEN_SOURCE define causes problems for Mac OS X we are told,
** so it is omitted there.  See ticket #2673.
**
** Later we learn that _XOPEN_SOURCE is poorly or incorrectly