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Overview
Comment:Handle the 4-byte integer case in the stackless routine.
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SHA1: 3f55484e81000c75e231f5580632a68e782ded4f
User & Date: drh 2014-08-22 14:56:13
Context
2014-08-22
15:19
Improve the performance and reduce the size of the sqlite3VdbeSerialGet() routine by avoiding the use of stack. check-in: ebc10e46 user: drh tags: trunk
14:56
Handle the 4-byte integer case in the stackless routine. Closed-Leaf check-in: 3f55484e user: drh tags: experimental
14:34
Get the sqlite3VdbeSerialGet() routine to run faster by avoiding the use of local variables. check-in: 8267d821 user: drh tags: experimental
Changes
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Changes to src/vdbeaux.c.

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/* Input "x" is a sequence of unsigned characters that represent a
** big-endian integer.  Return the equivalent native integer
*/
#define ONE_BYTE_INT(x)    ((i8)(x)[0])
#define TWO_BYTE_INT(x)    (256*(i8)((x)[0])|(x)[1])
#define THREE_BYTE_INT(x)  (65536*(i8)((x)[0])|((x)[1]<<8)|(x)[2])
#define FOUR_BYTE_UINT(x)  (((u32)(x)[0]<<24)|((x)[1]<<16)|((x)[2]<<8)|(x)[3])


/*
** Deserialize the data blob pointed to by buf as serial type serial_type
** and store the result in pMem.  Return the number of bytes read.
**
** This function is implemented as two separate routines for performance.
** The few cases that require local variables are broken out into a separate
................................................................................
** is avoided.
*/ 
static u32 SQLITE_NOINLINE serialGet(
  const unsigned char *buf,     /* Buffer to deserialize from */
  u32 serial_type,              /* Serial type to deserialize */
  Mem *pMem                     /* Memory cell to write value into */
){
  u64 x;
  u32 y = FOUR_BYTE_UINT(buf);
  if( serial_type==4 ){
    pMem->u.i = (i64)*(int*)&y;
    pMem->flags = MEM_Int;
    testcase( pMem->u.i<0 );
    return 4;
  }
  x = (((u64)y)<<32)|FOUR_BYTE_UINT(buf+4);

  if( serial_type==6 ){
    pMem->u.i = *(i64*)&x;
    pMem->flags = MEM_Int;
    testcase( pMem->u.i<0 );
  }else{
#if !defined(NDEBUG) && !defined(SQLITE_OMIT_FLOATING_POINT)
    /* Verify that integers and floating point values use the same
................................................................................
      return 2;
    }
    case 3: { /* 3-byte signed integer */
      pMem->u.i = THREE_BYTE_INT(buf);
      pMem->flags = MEM_Int;
      testcase( pMem->u.i<0 );
      return 3;






    }
    case 5: { /* 6-byte signed integer */
      pMem->u.i = FOUR_BYTE_UINT(buf+2) + (((i64)1)<<32)*TWO_BYTE_INT(buf);
      pMem->flags = MEM_Int;
      testcase( pMem->u.i<0 );
      return 6;
    }
    case 4:   /* 4-byte signed integer */
    case 6:   /* 8-byte signed integer */
    case 7: { /* IEEE floating point */
      /* These three cases require local variables, so do them in a 
      ** separate routine to avoid having to move the frame pointer in
      ** the common case */
      return serialGet(buf,serial_type,pMem);
    }
    case 8:    /* Integer 0 */
    case 9: {  /* Integer 1 */
      pMem->u.i = serial_type-8;
      pMem->flags = MEM_Int;
      return 0;







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/* Input "x" is a sequence of unsigned characters that represent a
** big-endian integer.  Return the equivalent native integer
*/
#define ONE_BYTE_INT(x)    ((i8)(x)[0])
#define TWO_BYTE_INT(x)    (256*(i8)((x)[0])|(x)[1])
#define THREE_BYTE_INT(x)  (65536*(i8)((x)[0])|((x)[1]<<8)|(x)[2])
#define FOUR_BYTE_UINT(x)  (((u32)(x)[0]<<24)|((x)[1]<<16)|((x)[2]<<8)|(x)[3])
#define FOUR_BYTE_INT(x) (16777216*(i8)((x)[0])|((x)[1]<<16)|((x)[2]<<8)|(x)[3])

/*
** Deserialize the data blob pointed to by buf as serial type serial_type
** and store the result in pMem.  Return the number of bytes read.
**
** This function is implemented as two separate routines for performance.
** The few cases that require local variables are broken out into a separate
................................................................................
** is avoided.
*/ 
static u32 SQLITE_NOINLINE serialGet(
  const unsigned char *buf,     /* Buffer to deserialize from */
  u32 serial_type,              /* Serial type to deserialize */
  Mem *pMem                     /* Memory cell to write value into */
){

  u64 x = FOUR_BYTE_UINT(buf);






  u32 y = FOUR_BYTE_UINT(buf+4);
  x = (x<<32) + y;
  if( serial_type==6 ){
    pMem->u.i = *(i64*)&x;
    pMem->flags = MEM_Int;
    testcase( pMem->u.i<0 );
  }else{
#if !defined(NDEBUG) && !defined(SQLITE_OMIT_FLOATING_POINT)
    /* Verify that integers and floating point values use the same
................................................................................
      return 2;
    }
    case 3: { /* 3-byte signed integer */
      pMem->u.i = THREE_BYTE_INT(buf);
      pMem->flags = MEM_Int;
      testcase( pMem->u.i<0 );
      return 3;
    }
    case 4: { /* 4-byte signed integer */
      pMem->u.i = FOUR_BYTE_INT(buf);
      pMem->flags = MEM_Int;
      testcase( pMem->u.i<0 );
      return 4;
    }
    case 5: { /* 6-byte signed integer */
      pMem->u.i = FOUR_BYTE_UINT(buf+2) + (((i64)1)<<32)*TWO_BYTE_INT(buf);
      pMem->flags = MEM_Int;
      testcase( pMem->u.i<0 );
      return 6;
    }

    case 6:   /* 8-byte signed integer */
    case 7: { /* IEEE floating point */
      /* These use local variables, so do them in a separate routine
      ** to avoid having to move the frame pointer in the common case */

      return serialGet(buf,serial_type,pMem);
    }
    case 8:    /* Integer 0 */
    case 9: {  /* Integer 1 */
      pMem->u.i = serial_type-8;
      pMem->flags = MEM_Int;
      return 0;