sqlite 3.5.1 windows source

1 files changed, 1017 insertions, 0 deletions

diff --git a/libraries/sqlite/win32/vdbemem.c b/libraries/sqlite/win32/vdbemem.c
new file mode 100755
index 0000000..58e2946
--- /dev/null
+++ b/libraries/sqlite/win32/vdbemem.c
@@ -0,0 +1,1017 @@
+/*
+** 2004 May 26
+**
+** 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 code use to manipulate "Mem" structure.  A "Mem"
+** stores a single value in the VDBE.  Mem is an opaque structure visible
+** only within the VDBE.  Interface routines refer to a Mem using the
+** name sqlite_value
+*/
+#include "sqliteInt.h"
+#include <math.h>
+#include <ctype.h>
+#include "vdbeInt.h"
+
+/*
+** Call sqlite3VdbeMemExpandBlob() on the supplied value (type Mem*)
+** P if required.
+*/
+#define expandBlob(P) (((P)->flags&MEM_Zero)?sqlite3VdbeMemExpandBlob(P):0)
+
+/*
+** If pMem is an object with a valid string representation, this routine
+** ensures the internal encoding for the string representation is
+** 'desiredEnc', one of SQLITE_UTF8, SQLITE_UTF16LE or SQLITE_UTF16BE.
+**
+** If pMem is not a string object, or the encoding of the string
+** representation is already stored using the requested encoding, then this
+** routine is a no-op.
+**
+** SQLITE_OK is returned if the conversion is successful (or not required).
+** SQLITE_NOMEM may be returned if a malloc() fails during conversion
+** between formats.
+*/
+int sqlite3VdbeChangeEncoding(Mem *pMem, int desiredEnc){
+  int rc;
+  if( !(pMem->flags&MEM_Str) || pMem->enc==desiredEnc ){
+    return SQLITE_OK;
+  }
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+#ifdef SQLITE_OMIT_UTF16
+  return SQLITE_ERROR;
+#else
+
+  /* MemTranslate() may return SQLITE_OK or SQLITE_NOMEM. If NOMEM is returned,
+  ** then the encoding of the value may not have changed.
+  */
+  rc = sqlite3VdbeMemTranslate(pMem, desiredEnc);
+  assert(rc==SQLITE_OK    || rc==SQLITE_NOMEM);
+  assert(rc==SQLITE_OK    || pMem->enc!=desiredEnc);
+  assert(rc==SQLITE_NOMEM || pMem->enc==desiredEnc);
+  return rc;
+#endif
+}
+
+/*
+** Make the given Mem object MEM_Dyn.
+**
+** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
+*/
+int sqlite3VdbeMemDynamicify(Mem *pMem){
+  int n;
+  u8 *z;
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  expandBlob(pMem);
+  if( (pMem->flags & (MEM_Ephem|MEM_Static|MEM_Short))==0 ){
+    return SQLITE_OK;
+  }
+  assert( (pMem->flags & MEM_Dyn)==0 );
+  n = pMem->n;
+  assert( pMem->flags & (MEM_Str|MEM_Blob) );
+  z = sqlite3DbMallocRaw(pMem->db, n+2 );
+  if( z==0 ){
+    return SQLITE_NOMEM;
+  }
+  pMem->flags |= MEM_Dyn|MEM_Term;
+  pMem->xDel = 0;
+  memcpy(z, pMem->z, n );
+  z[n] = 0;
+  z[n+1] = 0;
+  pMem->z = (char*)z;
+  pMem->flags &= ~(MEM_Ephem|MEM_Static|MEM_Short);
+  return SQLITE_OK;
+}
+
+/*
+** If the given Mem* has a zero-filled tail, turn it into an ordinary
+** blob stored in dynamically allocated space.
+*/
+#ifndef SQLITE_OMIT_INCRBLOB
+int sqlite3VdbeMemExpandBlob(Mem *pMem){
+  if( pMem->flags & MEM_Zero ){
+    char *pNew;
+    int nByte;
+    assert( (pMem->flags & MEM_Blob)!=0 );
+    nByte = pMem->n + pMem->u.i;
+    if( nByte<=0 ) nByte = 1;
+    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+    pNew = sqlite3DbMallocRaw(pMem->db, nByte);
+    if( pNew==0 ){
+      return SQLITE_NOMEM;
+    }
+    memcpy(pNew, pMem->z, pMem->n);
+    memset(&pNew[pMem->n], 0, pMem->u.i);
+    sqlite3VdbeMemRelease(pMem);
+    pMem->z = pNew;
+    pMem->n += pMem->u.i;
+    pMem->u.i = 0;
+    pMem->flags &= ~(MEM_Zero|MEM_Static|MEM_Ephem|MEM_Short|MEM_Term);
+    pMem->flags |= MEM_Dyn;
+  }
+  return SQLITE_OK;
+}
+#endif
+
+
+/*
+** Make the given Mem object either MEM_Short or MEM_Dyn so that bytes
+** of the Mem.z[] array can be modified.
+**
+** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
+*/
+int sqlite3VdbeMemMakeWriteable(Mem *pMem){
+  int n;
+  u8 *z;
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  expandBlob(pMem);
+  if( (pMem->flags & (MEM_Ephem|MEM_Static))==0 ){
+    return SQLITE_OK;
+  }
+  assert( (pMem->flags & MEM_Dyn)==0 );
+  assert( pMem->flags & (MEM_Str|MEM_Blob) );
+  if( (n = pMem->n)+2<sizeof(pMem->zShort) ){
+    z = (u8*)pMem->zShort;
+    pMem->flags |= MEM_Short|MEM_Term;
+  }else{
+    z = sqlite3DbMallocRaw(pMem->db, n+2 );
+    if( z==0 ){
+      return SQLITE_NOMEM;
+    }
+    pMem->flags |= MEM_Dyn|MEM_Term;
+    pMem->xDel = 0;
+  }
+  memcpy(z, pMem->z, n );
+  z[n] = 0;
+  z[n+1] = 0;
+  pMem->z = (char*)z;
+  pMem->flags &= ~(MEM_Ephem|MEM_Static);
+  assert(0==(1&(int)pMem->z));
+  return SQLITE_OK;
+}
+
+/*
+** Make sure the given Mem is \u0000 terminated.
+*/
+int sqlite3VdbeMemNulTerminate(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  if( (pMem->flags & MEM_Term)!=0 || (pMem->flags & MEM_Str)==0 ){
+    return SQLITE_OK;   /* Nothing to do */
+  }
+  if( pMem->flags & (MEM_Static|MEM_Ephem) ){
+    return sqlite3VdbeMemMakeWriteable(pMem);
+  }else{
+    char *z; 
+    sqlite3VdbeMemExpandBlob(pMem);
+    z = sqlite3DbMallocRaw(pMem->db, pMem->n+2);
+    if( !z ){
+       return SQLITE_NOMEM;
+    }
+    memcpy(z, pMem->z, pMem->n);
+    z[pMem->n] = 0;
+    z[pMem->n+1] = 0;
+    if( pMem->xDel ){
+      pMem->xDel(pMem->z);
+    }else{
+      sqlite3_free(pMem->z);
+    }
+    pMem->xDel = 0;
+    pMem->z = z;
+    pMem->flags |= MEM_Term;
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Add MEM_Str to the set of representations for the given Mem.  Numbers
+** are converted using sqlite3_snprintf().  Converting a BLOB to a string
+** is a no-op.
+**
+** Existing representations MEM_Int and MEM_Real are *not* invalidated.
+**
+** A MEM_Null value will never be passed to this function. This function is
+** used for converting values to text for returning to the user (i.e. via
+** sqlite3_value_text()), or for ensuring that values to be used as btree
+** keys are strings. In the former case a NULL pointer is returned the
+** user and the later is an internal programming error.
+*/
+int sqlite3VdbeMemStringify(Mem *pMem, int enc){
+  int rc = SQLITE_OK;
+  int fg = pMem->flags;
+  char *z = pMem->zShort;
+
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  assert( !(fg&MEM_Zero) );
+  assert( !(fg&(MEM_Str|MEM_Blob)) );
+  assert( fg&(MEM_Int|MEM_Real) );
+
+  /* For a Real or Integer, use sqlite3_snprintf() to produce the UTF-8
+  ** string representation of the value. Then, if the required encoding
+  ** is UTF-16le or UTF-16be do a translation.
+  ** 
+  ** FIX ME: It would be better if sqlite3_snprintf() could do UTF-16.
+  */
+  if( fg & MEM_Int ){
+    sqlite3_snprintf(NBFS, z, "%lld", pMem->u.i);
+  }else{
+    assert( fg & MEM_Real );
+    sqlite3_snprintf(NBFS, z, "%!.15g", pMem->r);
+  }
+  pMem->n = strlen(z);
+  pMem->z = z;
+  pMem->enc = SQLITE_UTF8;
+  pMem->flags |= MEM_Str | MEM_Short | MEM_Term;
+  sqlite3VdbeChangeEncoding(pMem, enc);
+  return rc;
+}
+
+/*
+** Memory cell pMem contains the context of an aggregate function.
+** This routine calls the finalize method for that function.  The
+** result of the aggregate is stored back into pMem.
+**
+** Return SQLITE_ERROR if the finalizer reports an error.  SQLITE_OK
+** otherwise.
+*/
+int sqlite3VdbeMemFinalize(Mem *pMem, FuncDef *pFunc){
+  int rc = SQLITE_OK;
+  if( pFunc && pFunc->xFinalize ){
+    sqlite3_context ctx;
+    assert( (pMem->flags & MEM_Null)!=0 || pFunc==pMem->u.pDef );
+    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+    ctx.s.flags = MEM_Null;
+    ctx.s.z = pMem->zShort;
+    ctx.s.db = pMem->db;
+    ctx.pMem = pMem;
+    ctx.pFunc = pFunc;
+    ctx.isError = 0;
+    pFunc->xFinalize(&ctx);
+    if( pMem->z && pMem->z!=pMem->zShort ){
+      sqlite3_free( pMem->z );
+    }
+    *pMem = ctx.s;
+    if( pMem->flags & MEM_Short ){
+      pMem->z = pMem->zShort;
+    }
+    rc = (ctx.isError?SQLITE_ERROR:SQLITE_OK);
+  }
+  return rc;
+}
+
+/*
+** Release any memory held by the Mem. This may leave the Mem in an
+** inconsistent state, for example with (Mem.z==0) and
+** (Mem.type==SQLITE_TEXT).
+*/
+void sqlite3VdbeMemRelease(Mem *p){
+  assert( p->db==0 || sqlite3_mutex_held(p->db->mutex) );
+  if( p->flags & (MEM_Dyn|MEM_Agg) ){
+    if( p->xDel ){
+      if( p->flags & MEM_Agg ){
+        sqlite3VdbeMemFinalize(p, p->u.pDef);
+        assert( (p->flags & MEM_Agg)==0 );
+        sqlite3VdbeMemRelease(p);
+      }else{
+        p->xDel((void *)p->z);
+      }
+    }else{
+      sqlite3_free(p->z);
+    }
+    p->z = 0;
+    p->xDel = 0;
+  }
+}
+
+/*
+** Return some kind of integer value which is the best we can do
+** at representing the value that *pMem describes as an integer.
+** If pMem is an integer, then the value is exact.  If pMem is
+** a floating-point then the value returned is the integer part.
+** If pMem is a string or blob, then we make an attempt to convert
+** it into a integer and return that.  If pMem is NULL, return 0.
+**
+** If pMem is a string, its encoding might be changed.
+*/
+i64 sqlite3VdbeIntValue(Mem *pMem){
+  int flags;
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  flags = pMem->flags;
+  if( flags & MEM_Int ){
+    return pMem->u.i;
+  }else if( flags & MEM_Real ){
+    return (i64)pMem->r;
+  }else if( flags & (MEM_Str|MEM_Blob) ){
+    i64 value;
+    pMem->flags |= MEM_Str;
+    if( sqlite3VdbeChangeEncoding(pMem, SQLITE_UTF8)
+       || sqlite3VdbeMemNulTerminate(pMem) ){
+      return 0;
+    }
+    assert( pMem->z );
+    sqlite3Atoi64(pMem->z, &value);
+    return value;
+  }else{
+    return 0;
+  }
+}
+
+/*
+** Return the best representation of pMem that we can get into a
+** double.  If pMem is already a double or an integer, return its
+** value.  If it is a string or blob, try to convert it to a double.
+** If it is a NULL, return 0.0.
+*/
+double sqlite3VdbeRealValue(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  if( pMem->flags & MEM_Real ){
+    return pMem->r;
+  }else if( pMem->flags & MEM_Int ){
+    return (double)pMem->u.i;
+  }else if( pMem->flags & (MEM_Str|MEM_Blob) ){
+    double val = 0.0;
+    pMem->flags |= MEM_Str;
+    if( sqlite3VdbeChangeEncoding(pMem, SQLITE_UTF8)
+       || sqlite3VdbeMemNulTerminate(pMem) ){
+      return 0.0;
+    }
+    assert( pMem->z );
+    sqlite3AtoF(pMem->z, &val);
+    return val;
+  }else{
+    return 0.0;
+  }
+}
+
+/*
+** The MEM structure is already a MEM_Real.  Try to also make it a
+** MEM_Int if we can.
+*/
+void sqlite3VdbeIntegerAffinity(Mem *pMem){
+  assert( pMem->flags & MEM_Real );
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  pMem->u.i = pMem->r;
+  if( ((double)pMem->u.i)==pMem->r ){
+    pMem->flags |= MEM_Int;
+  }
+}
+
+/*
+** Convert pMem to type integer.  Invalidate any prior representations.
+*/
+int sqlite3VdbeMemIntegerify(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  pMem->u.i = sqlite3VdbeIntValue(pMem);
+  sqlite3VdbeMemRelease(pMem);
+  pMem->flags = MEM_Int;
+  return SQLITE_OK;
+}
+
+/*
+** Convert pMem so that it is of type MEM_Real.
+** Invalidate any prior representations.
+*/
+int sqlite3VdbeMemRealify(Mem *pMem){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  pMem->r = sqlite3VdbeRealValue(pMem);
+  sqlite3VdbeMemRelease(pMem);
+  pMem->flags = MEM_Real;
+  return SQLITE_OK;
+}
+
+/*
+** Convert pMem so that it has types MEM_Real or MEM_Int or both.
+** Invalidate any prior representations.
+*/
+int sqlite3VdbeMemNumerify(Mem *pMem){
+  double r1, r2;
+  i64 i;
+  assert( (pMem->flags & (MEM_Int|MEM_Real|MEM_Null))==0 );
+  assert( (pMem->flags & (MEM_Blob|MEM_Str))!=0 );
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  r1 = sqlite3VdbeRealValue(pMem);
+  i = (i64)r1;
+  r2 = (double)i;
+  if( r1==r2 ){
+    sqlite3VdbeMemIntegerify(pMem);
+  }else{
+    pMem->r = r1;
+    pMem->flags = MEM_Real;
+    sqlite3VdbeMemRelease(pMem);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Delete any previous value and set the value stored in *pMem to NULL.
+*/
+void sqlite3VdbeMemSetNull(Mem *pMem){
+  sqlite3VdbeMemRelease(pMem);
+  pMem->flags = MEM_Null;
+  pMem->type = SQLITE_NULL;
+  pMem->n = 0;
+}
+
+/*
+** Delete any previous value and set the value to be a BLOB of length
+** n containing all zeros.
+*/
+void sqlite3VdbeMemSetZeroBlob(Mem *pMem, int n){
+  sqlite3VdbeMemRelease(pMem);
+  pMem->flags = MEM_Blob|MEM_Zero|MEM_Short;
+  pMem->type = SQLITE_BLOB;
+  pMem->n = 0;
+  if( n<0 ) n = 0;
+  pMem->u.i = n;
+  pMem->z = pMem->zShort;
+  pMem->enc = SQLITE_UTF8;
+}
+
+/*
+** Delete any previous value and set the value stored in *pMem to val,
+** manifest type INTEGER.
+*/
+void sqlite3VdbeMemSetInt64(Mem *pMem, i64 val){
+  sqlite3VdbeMemRelease(pMem);
+  pMem->u.i = val;
+  pMem->flags = MEM_Int;
+  pMem->type = SQLITE_INTEGER;
+}
+
+/*
+** Delete any previous value and set the value stored in *pMem to val,
+** manifest type REAL.
+*/
+void sqlite3VdbeMemSetDouble(Mem *pMem, double val){
+  if( sqlite3_isnan(val) ){
+    sqlite3VdbeMemSetNull(pMem);
+  }else{
+    sqlite3VdbeMemRelease(pMem);
+    pMem->r = val;
+    pMem->flags = MEM_Real;
+    pMem->type = SQLITE_FLOAT;
+  }
+}
+
+/*
+** Return true if the Mem object contains a TEXT or BLOB that is
+** too large - whose size exceeds SQLITE_MAX_LENGTH.
+*/
+int sqlite3VdbeMemTooBig(Mem *p){
+  if( p->flags & (MEM_Str|MEM_Blob) ){
+    int n = p->n;
+    if( p->flags & MEM_Zero ){
+      n += p->u.i;
+    }
+    return n>SQLITE_MAX_LENGTH;
+  }
+  return 0; 
+}
+
+/*
+** Make an shallow copy of pFrom into pTo.  Prior contents of
+** pTo are overwritten.  The pFrom->z field is not duplicated.  If
+** pFrom->z is used, then pTo->z points to the same thing as pFrom->z
+** and flags gets srcType (either MEM_Ephem or MEM_Static).
+*/
+void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
+  memcpy(pTo, pFrom, sizeof(*pFrom)-sizeof(pFrom->zShort));
+  pTo->xDel = 0;
+  if( pTo->flags & (MEM_Str|MEM_Blob) ){
+    pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Short|MEM_Ephem);
+    assert( srcType==MEM_Ephem || srcType==MEM_Static );
+    pTo->flags |= srcType;
+  }
+}
+
+/*
+** Make a full copy of pFrom into pTo.  Prior contents of pTo are
+** freed before the copy is made.
+*/
+int sqlite3VdbeMemCopy(Mem *pTo, const Mem *pFrom){
+  int rc;
+  if( pTo->flags & MEM_Dyn ){
+    sqlite3VdbeMemRelease(pTo);
+  }
+  sqlite3VdbeMemShallowCopy(pTo, pFrom, MEM_Ephem);
+  if( pTo->flags & MEM_Ephem ){
+    rc = sqlite3VdbeMemMakeWriteable(pTo);
+  }else{
+    rc = SQLITE_OK;
+  }
+  return rc;
+}
+
+/*
+** Transfer the contents of pFrom to pTo. Any existing value in pTo is
+** freed. If pFrom contains ephemeral data, a copy is made.
+**
+** pFrom contains an SQL NULL when this routine returns.  SQLITE_NOMEM
+** might be returned if pFrom held ephemeral data and we were unable
+** to allocate enough space to make a copy.
+*/
+int sqlite3VdbeMemMove(Mem *pTo, Mem *pFrom){
+  int rc;
+  assert( pFrom->db==0 || sqlite3_mutex_held(pFrom->db->mutex) );
+  assert( pTo->db==0 || sqlite3_mutex_held(pTo->db->mutex) );
+  assert( pFrom->db==0 || pTo->db==0 || pFrom->db==pTo->db );
+  if( pTo->flags & MEM_Dyn ){
+    sqlite3VdbeMemRelease(pTo);
+  }
+  memcpy(pTo, pFrom, sizeof(Mem));
+  if( pFrom->flags & MEM_Short ){
+    pTo->z = pTo->zShort;
+  }
+  pFrom->flags = MEM_Null;
+  pFrom->xDel = 0;
+  if( pTo->flags & MEM_Ephem ){
+    rc = sqlite3VdbeMemMakeWriteable(pTo);
+  }else{
+    rc = SQLITE_OK;
+  }
+  return rc;
+}
+
+/*
+** Change the value of a Mem to be a string or a BLOB.
+*/
+int sqlite3VdbeMemSetStr(
+  Mem *pMem,          /* Memory cell to set to string value */
+  const char *z,      /* String pointer */
+  int n,              /* Bytes in string, or negative */
+  u8 enc,             /* Encoding of z.  0 for BLOBs */
+  void (*xDel)(void*) /* Destructor function */
+){
+  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
+  sqlite3VdbeMemRelease(pMem);
+  if( !z ){
+    pMem->flags = MEM_Null;
+    pMem->type = SQLITE_NULL;
+    return SQLITE_OK;
+  }
+  pMem->z = (char *)z;
+  if( xDel==SQLITE_STATIC ){
+    pMem->flags = MEM_Static;
+  }else if( xDel==SQLITE_TRANSIENT ){
+    pMem->flags = MEM_Ephem;
+  }else{
+    pMem->flags = MEM_Dyn;
+    pMem->xDel = xDel;
+  }
+
+  pMem->enc = enc;
+  pMem->type = enc==0 ? SQLITE_BLOB : SQLITE_TEXT;
+  pMem->n = n;
+
+  assert( enc==0 || enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE 
+      || enc==SQLITE_UTF16BE );
+  switch( enc ){
+    case 0:
+      pMem->flags |= MEM_Blob;
+      pMem->enc = SQLITE_UTF8;
+      break;
+
+    case SQLITE_UTF8:
+      pMem->flags |= MEM_Str;
+      if( n<0 ){
+        pMem->n = strlen(z);
+        pMem->flags |= MEM_Term;
+      }
+      break;
+
+#ifndef SQLITE_OMIT_UTF16
+    case SQLITE_UTF16LE:
+    case SQLITE_UTF16BE:
+      pMem->flags |= MEM_Str;
+      if( pMem->n<0 ){
+        pMem->n = sqlite3Utf16ByteLen(pMem->z,-1);
+        pMem->flags |= MEM_Term;
+      }
+      if( sqlite3VdbeMemHandleBom(pMem) ){
+        return SQLITE_NOMEM;
+      }
+#endif /* SQLITE_OMIT_UTF16 */
+  }
+  if( pMem->flags&MEM_Ephem ){
+    return sqlite3VdbeMemMakeWriteable(pMem);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Compare the values contained by the two memory cells, returning
+** negative, zero or positive if pMem1 is less than, equal to, or greater
+** than pMem2. Sorting order is NULL's first, followed by numbers (integers
+** and reals) sorted numerically, followed by text ordered by the collating
+** sequence pColl and finally blob's ordered by memcmp().
+**
+** Two NULL values are considered equal by this function.
+*/
+int sqlite3MemCompare(const Mem *pMem1, const Mem *pMem2, const CollSeq *pColl){
+  int rc;
+  int f1, f2;
+  int combined_flags;
+
+  /* Interchange pMem1 and pMem2 if the collating sequence specifies
+  ** DESC order.
+  */
+  f1 = pMem1->flags;
+  f2 = pMem2->flags;
+  combined_flags = f1|f2;
+ 
+  /* If one value is NULL, it is less than the other. If both values
+  ** are NULL, return 0.
+  */
+  if( combined_flags&MEM_Null ){
+    return (f2&MEM_Null) - (f1&MEM_Null);
+  }
+
+  /* If one value is a number and the other is not, the number is less.
+  ** If both are numbers, compare as reals if one is a real, or as integers
+  ** if both values are integers.
+  */
+  if( combined_flags&(MEM_Int|MEM_Real) ){
+    if( !(f1&(MEM_Int|MEM_Real)) ){
+      return 1;
+    }
+    if( !(f2&(MEM_Int|MEM_Real)) ){
+      return -1;
+    }
+    if( (f1 & f2 & MEM_Int)==0 ){
+      double r1, r2;
+      if( (f1&MEM_Real)==0 ){
+        r1 = pMem1->u.i;
+      }else{
+        r1 = pMem1->r;
+      }
+      if( (f2&MEM_Real)==0 ){
+        r2 = pMem2->u.i;
+      }else{
+        r2 = pMem2->r;
+      }
+      if( r1<r2 ) return -1;
+      if( r1>r2 ) return 1;
+      return 0;
+    }else{
+      assert( f1&MEM_Int );
+      assert( f2&MEM_Int );
+      if( pMem1->u.i < pMem2->u.i ) return -1;
+      if( pMem1->u.i > pMem2->u.i ) return 1;
+      return 0;
+    }
+  }
+
+  /* If one value is a string and the other is a blob, the string is less.
+  ** If both are strings, compare using the collating functions.
+  */
+  if( combined_flags&MEM_Str ){
+    if( (f1 & MEM_Str)==0 ){
+      return 1;
+    }
+    if( (f2 & MEM_Str)==0 ){
+      return -1;
+    }
+
+    assert( pMem1->enc==pMem2->enc );
+    assert( pMem1->enc==SQLITE_UTF8 || 
+            pMem1->enc==SQLITE_UTF16LE || pMem1->enc==SQLITE_UTF16BE );
+
+    /* The collation sequence must be defined at this point, even if
+    ** the user deletes the collation sequence after the vdbe program is
+    ** compiled (this was not always the case).
+    */
+    assert( !pColl || pColl->xCmp );
+
+    if( pColl ){
+      if( pMem1->enc==pColl->enc ){
+        /* The strings are already in the correct encoding.  Call the
+        ** comparison function directly */
+        return pColl->xCmp(pColl->pUser,pMem1->n,pMem1->z,pMem2->n,pMem2->z);
+      }else{
+        u8 origEnc = pMem1->enc;
+        const void *v1, *v2;
+        int n1, n2;
+        /* Convert the strings into the encoding that the comparison
+        ** function expects */
+        v1 = sqlite3ValueText((sqlite3_value*)pMem1, pColl->enc);
+        n1 = v1==0 ? 0 : pMem1->n;
+        assert( n1==sqlite3ValueBytes((sqlite3_value*)pMem1, pColl->enc) );
+        v2 = sqlite3ValueText((sqlite3_value*)pMem2, pColl->enc);
+        n2 = v2==0 ? 0 : pMem2->n;
+        assert( n2==sqlite3ValueBytes((sqlite3_value*)pMem2, pColl->enc) );
+        /* Do the comparison */
+        rc = pColl->xCmp(pColl->pUser, n1, v1, n2, v2);
+        /* Convert the strings back into the database encoding */
+        sqlite3ValueText((sqlite3_value*)pMem1, origEnc);
+        sqlite3ValueText((sqlite3_value*)pMem2, origEnc);
+        return rc;
+      }
+    }
+    /* If a NULL pointer was passed as the collate function, fall through
+    ** to the blob case and use memcmp().  */
+  }
+ 
+  /* Both values must be blobs.  Compare using memcmp().  */
+  rc = memcmp(pMem1->z, pMem2->z, (pMem1->n>pMem2->n)?pMem2->n:pMem1->n);
+  if( rc==0 ){
+    rc = pMem1->n - pMem2->n;
+  }
+  return rc;
+}
+
+/*
+** Move data out of a btree key or data field and into a Mem structure.
+** The data or key is taken from the entry that pCur is currently pointing
+** to.  offset and amt determine what portion of the data or key to retrieve.
+** key is true to get the key or false to get data.  The result is written
+** into the pMem element.
+**
+** The pMem structure is assumed to be uninitialized.  Any prior content
+** is overwritten without being freed.
+**
+** If this routine fails for any reason (malloc returns NULL or unable
+** to read from the disk) then the pMem is left in an inconsistent state.
+*/
+int sqlite3VdbeMemFromBtree(
+  BtCursor *pCur,   /* Cursor pointing at record to retrieve. */
+  int offset,       /* Offset from the start of data to return bytes from. */
+  int amt,          /* Number of bytes to return. */
+  int key,          /* If true, retrieve from the btree key, not data. */
+  Mem *pMem         /* OUT: Return data in this Mem structure. */
+){
+  char *zData;       /* Data from the btree layer */
+  int available = 0; /* Number of bytes available on the local btree page */
+  sqlite3 *db;       /* Database connection */
+
+  db = sqlite3BtreeCursorDb(pCur);
+  assert( sqlite3_mutex_held(db->mutex) );
+  if( key ){
+    zData = (char *)sqlite3BtreeKeyFetch(pCur, &available);
+  }else{
+    zData = (char *)sqlite3BtreeDataFetch(pCur, &available);
+  }
+  assert( zData!=0 );
+
+  pMem->db = db;
+  pMem->n = amt;
+  if( offset+amt<=available ){
+    pMem->z = &zData[offset];
+    pMem->flags = MEM_Blob|MEM_Ephem;
+  }else{
+    int rc;
+    if( amt>NBFS-2 ){
+      zData = (char *)sqlite3DbMallocRaw(db, amt+2);
+      if( !zData ){
+        return SQLITE_NOMEM;
+      }
+      pMem->flags = MEM_Blob|MEM_Dyn|MEM_Term;
+      pMem->xDel = 0;
+    }else{
+      zData = &(pMem->zShort[0]);
+      pMem->flags = MEM_Blob|MEM_Short|MEM_Term;
+    }
+    pMem->z = zData;
+    pMem->enc = 0;
+    pMem->type = SQLITE_BLOB;
+
+    if( key ){
+      rc = sqlite3BtreeKey(pCur, offset, amt, zData);
+    }else{
+      rc = sqlite3BtreeData(pCur, offset, amt, zData);
+    }
+    zData[amt] = 0;
+    zData[amt+1] = 0;
+    if( rc!=SQLITE_OK ){
+      if( amt>NBFS-2 ){
+        assert( zData!=pMem->zShort );
+        assert( pMem->flags & MEM_Dyn );
+        sqlite3_free(zData);
+      } else {
+        assert( zData==pMem->zShort );
+        assert( pMem->flags & MEM_Short );
+      }
+      return rc;
+    }
+  }
+
+  return SQLITE_OK;
+}
+
+#ifndef NDEBUG
+/*
+** Perform various checks on the memory cell pMem. An assert() will
+** fail if pMem is internally inconsistent.
+*/
+void sqlite3VdbeMemSanity(Mem *pMem){
+  int flags = pMem->flags;
+  assert( flags!=0 );  /* Must define some type */
+  if( flags & (MEM_Str|MEM_Blob) ){
+    int x = flags & (MEM_Static|MEM_Dyn|MEM_Ephem|MEM_Short);
+    assert( x!=0 );            /* Strings must define a string subtype */
+    assert( (x & (x-1))==0 );  /* Only one string subtype can be defined */
+    assert( pMem->z!=0 );      /* Strings must have a value */
+    /* Mem.z points to Mem.zShort iff the subtype is MEM_Short */
+    assert( (x & MEM_Short)==0 || pMem->z==pMem->zShort );
+    assert( (x & MEM_Short)!=0 || pMem->z!=pMem->zShort );
+    /* No destructor unless there is MEM_Dyn */
+    assert( pMem->xDel==0 || (pMem->flags & MEM_Dyn)!=0 );
+
+    if( (flags & MEM_Str) ){
+      assert( pMem->enc==SQLITE_UTF8 || 
+              pMem->enc==SQLITE_UTF16BE ||
+              pMem->enc==SQLITE_UTF16LE 
+      );
+      /* If the string is UTF-8 encoded and nul terminated, then pMem->n
+      ** must be the length of the string.  (Later:)  If the database file
+      ** has been corrupted, '\000' characters might have been inserted
+      ** into the middle of the string.  In that case, the strlen() might
+      ** be less.
+      */
+      if( pMem->enc==SQLITE_UTF8 && (flags & MEM_Term) ){ 
+        assert( strlen(pMem->z)<=pMem->n );
+        assert( pMem->z[pMem->n]==0 );
+      }
+    }
+  }else{
+    /* Cannot define a string subtype for non-string objects */
+    assert( (pMem->flags & (MEM_Static|MEM_Dyn|MEM_Ephem|MEM_Short))==0 );
+    assert( pMem->xDel==0 );
+  }
+  /* MEM_Null excludes all other types */
+  assert( (pMem->flags&(MEM_Str|MEM_Int|MEM_Real|MEM_Blob))==0
+          || (pMem->flags&MEM_Null)==0 );
+  /* If the MEM is both real and integer, the values are equal */
+  assert( (pMem->flags & (MEM_Int|MEM_Real))!=(MEM_Int|MEM_Real) 
+          || pMem->r==pMem->u.i );
+}
+#endif
+
+/* This function is only available internally, it is not part of the
+** external API. It works in a similar way to sqlite3_value_text(),
+** except the data returned is in the encoding specified by the second
+** parameter, which must be one of SQLITE_UTF16BE, SQLITE_UTF16LE or
+** SQLITE_UTF8.
+**
+** (2006-02-16:)  The enc value can be or-ed with SQLITE_UTF16_ALIGNED.
+** If that is the case, then the result must be aligned on an even byte
+** boundary.
+*/
+const void *sqlite3ValueText(sqlite3_value* pVal, u8 enc){
+  if( !pVal ) return 0;
+
+  assert( pVal->db==0 || sqlite3_mutex_held(pVal->db->mutex) );
+  assert( (enc&3)==(enc&~SQLITE_UTF16_ALIGNED) );
+
+  if( pVal->flags&MEM_Null ){
+    return 0;
+  }
+  assert( (MEM_Blob>>3) == MEM_Str );
+  pVal->flags |= (pVal->flags & MEM_Blob)>>3;
+  expandBlob(pVal);
+  if( pVal->flags&MEM_Str ){
+    sqlite3VdbeChangeEncoding(pVal, enc & ~SQLITE_UTF16_ALIGNED);
+    if( (enc & SQLITE_UTF16_ALIGNED)!=0 && 1==(1&(int)pVal->z) ){
+      assert( (pVal->flags & (MEM_Ephem|MEM_Static))!=0 );
+      if( sqlite3VdbeMemMakeWriteable(pVal)!=SQLITE_OK ){
+        return 0;
+      }
+    }
+    sqlite3VdbeMemNulTerminate(pVal);
+  }else{
+    assert( (pVal->flags&MEM_Blob)==0 );
+    sqlite3VdbeMemStringify(pVal, enc);
+    assert( 0==(1&(int)pVal->z) );
+  }
+  assert(pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) || pVal->db==0
+              || pVal->db->mallocFailed );
+  if( pVal->enc==(enc & ~SQLITE_UTF16_ALIGNED) ){
+    return pVal->z;
+  }else{
+    return 0;
+  }
+}
+
+/*
+** Create a new sqlite3_value object.
+*/
+sqlite3_value *sqlite3ValueNew(sqlite3 *db){
+  Mem *p = sqlite3DbMallocZero(db, sizeof(*p));
+  if( p ){
+    p->flags = MEM_Null;
+    p->type = SQLITE_NULL;
+    p->db = db;
+  }
+  return p;
+}
+
+/*
+** Create a new sqlite3_value object, containing the value of pExpr.
+**
+** This only works for very simple expressions that consist of one constant
+** token (i.e. "5", "5.1", "NULL", "'a string'"). If the expression can
+** be converted directly into a value, then the value is allocated and
+** a pointer written to *ppVal. The caller is responsible for deallocating
+** the value by passing it to sqlite3ValueFree() later on. If the expression
+** cannot be converted to a value, then *ppVal is set to NULL.
+*/
+int sqlite3ValueFromExpr(
+  sqlite3 *db,              /* The database connection */
+  Expr *pExpr,              /* The expression to evaluate */
+  u8 enc,                   /* Encoding to use */
+  u8 affinity,              /* Affinity to use */
+  sqlite3_value **ppVal     /* Write the new value here */
+){
+  int op;
+  char *zVal = 0;
+  sqlite3_value *pVal = 0;
+
+  if( !pExpr ){
+    *ppVal = 0;
+    return SQLITE_OK;
+  }
+  op = pExpr->op;
+
+  if( op==TK_STRING || op==TK_FLOAT || op==TK_INTEGER ){
+    zVal = sqlite3StrNDup((char*)pExpr->token.z, pExpr->token.n);
+    pVal = sqlite3ValueNew(db);
+    if( !zVal || !pVal ) goto no_mem;
+    sqlite3Dequote(zVal);
+    sqlite3ValueSetStr(pVal, -1, zVal, SQLITE_UTF8, sqlite3_free);
+    if( (op==TK_INTEGER || op==TK_FLOAT ) && affinity==SQLITE_AFF_NONE ){
+      sqlite3ValueApplyAffinity(pVal, SQLITE_AFF_NUMERIC, enc);
+    }else{
+      sqlite3ValueApplyAffinity(pVal, affinity, enc);
+    }
+  }else if( op==TK_UMINUS ) {
+    if( SQLITE_OK==sqlite3ValueFromExpr(db,pExpr->pLeft,enc,affinity,&pVal) ){
+      pVal->u.i = -1 * pVal->u.i;
+      pVal->r = -1.0 * pVal->r;
+    }
+  }
+#ifndef SQLITE_OMIT_BLOB_LITERAL
+  else if( op==TK_BLOB ){
+    int nVal;
+    pVal = sqlite3ValueNew(db);
+    zVal = sqlite3StrNDup((char*)pExpr->token.z+1, pExpr->token.n-1);
+    if( !zVal || !pVal ) goto no_mem;
+    sqlite3Dequote(zVal);
+    nVal = strlen(zVal)/2;
+    sqlite3VdbeMemSetStr(pVal, sqlite3HexToBlob(db, zVal), nVal,0,sqlite3_free);
+    sqlite3_free(zVal);
+  }
+#endif
+
+  *ppVal = pVal;
+  return SQLITE_OK;
+
+no_mem:
+  db->mallocFailed = 1;
+  sqlite3_free(zVal);
+  sqlite3ValueFree(pVal);
+  *ppVal = 0;
+  return SQLITE_NOMEM;
+}
+
+/*
+** Change the string value of an sqlite3_value object
+*/
+void sqlite3ValueSetStr(
+  sqlite3_value *v,     /* Value to be set */
+  int n,                /* Length of string z */
+  const void *z,        /* Text of the new string */
+  u8 enc,               /* Encoding to use */
+  void (*xDel)(void*)   /* Destructor for the string */
+){
+  if( v ) sqlite3VdbeMemSetStr((Mem *)v, z, n, enc, xDel);
+}
+
+/*
+** Free an sqlite3_value object
+*/
+void sqlite3ValueFree(sqlite3_value *v){
+  if( !v ) return;
+  sqlite3ValueSetStr(v, 0, 0, SQLITE_UTF8, SQLITE_STATIC);
+  sqlite3_free(v);
+}
+
+/*
+** Return the number of bytes in the sqlite3_value object assuming
+** that it uses the encoding "enc"
+*/
+int sqlite3ValueBytes(sqlite3_value *pVal, u8 enc){
+  Mem *p = (Mem*)pVal;
+  if( (p->flags & MEM_Blob)!=0 || sqlite3ValueText(pVal, enc) ){
+    if( p->flags & MEM_Zero ){
+      return p->n+p->u.i;
+    }else{
+      return p->n;
+    }
+  }
+  return 0;
+}