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Overview
Comment:Optimization to the round() SQL function for large input values without a fractional part.
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SHA3-256: e95138f5f4febde598f39e031d6e4f4d5ad0adbd8dcdd34fd0baaa78ab393417
User & Date: drh 2019-05-30 13:47:10
References
2019-06-07
22:51
Remove code in the round() SQL function that became unreachable due to the optimization of check-in [e95138f5f4febde5] check-in: b141bae3 user: drh tags: trunk
Context
2019-06-03
15:09
Fix harmless compiler warning in lemon. check-in: 2da0eea0 user: mistachkin tags: trunk
2019-05-30
13:47
Optimization to the round() SQL function for large input values without a fractional part. check-in: e95138f5 user: drh tags: trunk
00:46
Smaller and faster sqlite3IsNaN() implementation makes deserialization of floating point values much faster. check-in: ea748ede user: drh tags: trunk
Changes
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Changes to src/func.c.

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  }
  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
  r = sqlite3_value_double(argv[0]);
  /* If Y==0 and X will fit in a 64-bit int,
  ** handle the rounding directly,
  ** otherwise use printf.
  */
  if( n==0 && r>=0 && r<LARGEST_INT64-1 ){
    r = (double)((sqlite_int64)(r+0.5));
  }else if( n==0 && r<0 && (-r)<LARGEST_INT64-1 ){
    r = -(double)((sqlite_int64)((-r)+0.5));
  }else{
    zBuf = sqlite3_mprintf("%.*f",n,r);
    if( zBuf==0 ){
      sqlite3_result_error_nomem(context);
      return;
    }
    if( !sqlite3AtoF(zBuf, &r, sqlite3Strlen30(zBuf), SQLITE_UTF8) ){







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  }
  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
  r = sqlite3_value_double(argv[0]);
  /* If Y==0 and X will fit in a 64-bit int,
  ** handle the rounding directly,
  ** otherwise use printf.
  */
  if( r<-4503599627370496.0 || r>+4503599627370496.0 ){
    /* The value has no fractional part so there is nothing to round */
  }else if( n==0 ){  
    r = (double)((sqlite_int64)(r+(r<0?-0.5:+0.5)));
  }else{
    zBuf = sqlite3_mprintf("%.*f",n,r);
    if( zBuf==0 ){
      sqlite3_result_error_nomem(context);
      return;
    }
    if( !sqlite3AtoF(zBuf, &r, sqlite3Strlen30(zBuf), SQLITE_UTF8) ){

Changes to src/util.c.

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  if( enc==SQLITE_UTF8 ){
    incr = 1;
  }else{
    int i;
    incr = 2;
    assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );


    for(i=3-enc; i<length && z[i]==0; i+=2){}
    if( i<length ) eType = -100;
    zEnd = &z[i^1];
    z += (enc&1);
  }

  /* skip leading spaces */







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  if( enc==SQLITE_UTF8 ){
    incr = 1;
  }else{
    int i;
    incr = 2;
    assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
    testcase( enc==SQLITE_UTF16LE );
    testcase( enc==SQLITE_UTF16BE );
    for(i=3-enc; i<length && z[i]==0; i+=2){}
    if( i<length ) eType = -100;
    zEnd = &z[i^1];
    z += (enc&1);
  }

  /* skip leading spaces */