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Overview
| Comment: | More simplification of the sqlite3AtoF() routine. Add special comments to indicate branches that are for optimization purposes only and that give the correct answer even if always or never taken. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: | 0065fe97cb8e5076acae1bf1560fd2f69dab9014 |
| User & Date: | drh 2016-04-27 15:24:13 |
Context
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2016-04-28
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| 00:32 | Change the sqlite3Atoi64() routine so that it returns failure if not all of the input characters are consumed, even if it consumed all characters up to the first 0x00. This has no impact on external APIs as far as I can tell. check-in: 46d4ffff user: drh tags: trunk | |
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2016-04-27
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| 18:54 | Modify the permutations.test script so as to set any permutation specific configuration values before running each individual test script. check-in: 2662d8fe user: dan tags: permutations-fix | |
| 15:24 | More simplification of the sqlite3AtoF() routine. Add special comments to indicate branches that are for optimization purposes only and that give the correct answer even if always or never taken. check-in: 0065fe97 user: drh tags: trunk | |
| 02:35 | Remove still more unnecessary branches from sqlite3AtoF(). check-in: 3adfe9f3 user: drh tags: trunk | |
Changes
Changes to src/util.c.
351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 ... 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 ... 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 |
i64 s = 0; /* significand */
int d = 0; /* adjust exponent for shifting decimal point */
int esign = 1; /* sign of exponent */
int e = 0; /* exponent */
int eValid = 1; /* True exponent is either not used or is well-formed */
double result;
int nDigits = 0;
int nonNum = 0;
assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
*pResult = 0.0; /* Default return value, in case of an error */
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){}
nonNum = i<length;
zEnd = z+i+enc-3;
z += (enc&1);
}
/* skip leading spaces */
while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
if( z>=zEnd ) return 0;
................................................................................
}
if( z>=zEnd ) goto do_atof_calc;
/* if exponent is present */
if( *z=='e' || *z=='E' ){
z+=incr;
eValid = 0;
if( z>=zEnd ) goto do_atof_calc;
/* get sign of exponent */
if( *z=='-' ){
esign = -1;
z+=incr;
}else if( *z=='+' ){
z+=incr;
}
................................................................................
if( e<0 ) {
esign = -1;
e *= -1;
} else {
esign = 1;
}
/* if 0 significand */
if( !s ) {
/* In the IEEE 754 standard, zero is signed.
** Add the sign if we've seen at least one digit */
result = sign<0 ? -(double)0 : (double)0;
} else {
/* attempt to reduce exponent */
if( esign>0 ){
while( s<(LARGEST_INT64/10) && e>0 ) e--,s*=10;
}else{
while( !(s%10) && e>0 ) e--,s/=10;
}
/* adjust the sign of significand */
s = sign<0 ? -s : s;
/* if exponent, scale significand as appropriate
** and store in result. */
if( e ){
LONGDOUBLE_TYPE scale = 1.0;
/* attempt to handle extremely small/large numbers better */
if( e>307 && e<342 ){
while( e%308 ) { scale *= 1.0e+1; e -= 1; }
if( esign<0 ){
result = s / scale;
result /= 1.0e+308;
}else{
result = s * scale;
result *= 1.0e+308;
}
}else if( e>=342 ){
if( esign<0 ){
result = 0.0*s;
}else{
result = 1e308*1e308*s; /* Infinity */
}
}else{
/* 1.0e+22 is the largest power of 10 than can be
** represented exactly. */
while( e%22 ) { scale *= 1.0e+1; e -= 1; }
while( e>0 ) { scale *= 1.0e+22; e -= 22; }
if( esign<0 ){
result = s / scale;
}else{
result = s * scale;
}
}
} else {
result = (double)s;
}
}
/* store the result */
*pResult = result;
/* return true if number and no extra non-whitespace chracters after */
return z>=zEnd && nDigits>0 && eValid && nonNum==0;
#else
return !sqlite3Atoi64(z, pResult, length, enc);
#endif /* SQLITE_OMIT_FLOATING_POINT */
}
/*
** Compare the 19-character string zNum against the text representation
|
| | > > > > | > < | | < | > > > > > > | < > > | < > > > > | | | | > | | | | | | | | | | | | | > < < | |
351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 ... 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 ... 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 |
i64 s = 0; /* significand */ int d = 0; /* adjust exponent for shifting decimal point */ int esign = 1; /* sign of exponent */ int e = 0; /* exponent */ int eValid = 1; /* True exponent is either not used or is well-formed */ double result; int nDigits = 0; int nonNum = 0; /* True if input contains UTF16 with high byte non-zero */ assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE ); *pResult = 0.0; /* Default return value, in case of an error */ 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){} nonNum = i<length; zEnd = &z[i^1]; z += (enc&1); } /* skip leading spaces */ while( z<zEnd && sqlite3Isspace(*z) ) z+=incr; if( z>=zEnd ) return 0; ................................................................................ } if( z>=zEnd ) goto do_atof_calc; /* if exponent is present */ if( *z=='e' || *z=='E' ){ z+=incr; eValid = 0; /* This branch is needed to avoid a (harmless) buffer overread. The ** special comment alerts the mutation tester that the correct answer ** is obtained even if the branch is omitted */ if( z>=zEnd ) goto do_atof_calc; /*PREVENTS-HARMLESS-OVERREAD*/ /* get sign of exponent */ if( *z=='-' ){ esign = -1; z+=incr; }else if( *z=='+' ){ z+=incr; } ................................................................................ if( e<0 ) { esign = -1; e *= -1; } else { esign = 1; } if( s==0 ) { /* In the IEEE 754 standard, zero is signed. */ result = sign<0 ? -(double)0 : (double)0; } else { /* Attempt to reduce exponent. ** ** Branches that are not required for the correct answer but which only ** help to obtain the correct answer faster are marked with special ** comments, as a hint to the mutation tester. */ while( e>0 ){ /*OPTIMIZATION-IF-TRUE*/ if( esign>0 ){ if( s>=(LARGEST_INT64/10) ) break; /*OPTIMIZATION-IF-FALSE*/ s *= 10; }else{ if( s%10!=0 ) break; /*OPTIMIZATION-IF-FALSE*/ s /= 10; } e--; } /* adjust the sign of significand */ s = sign<0 ? -s : s; if( e==0 ){ /*OPTIMIZATION-IF-TRUE*/ result = (double)s; }else{ LONGDOUBLE_TYPE scale = 1.0; /* attempt to handle extremely small/large numbers better */ if( e>307 ){ /*OPTIMIZATION-IF-TRUE*/ if( e<342 ){ /*OPTIMIZATION-IF-TRUE*/ while( e%308 ) { scale *= 1.0e+1; e -= 1; } if( esign<0 ){ result = s / scale; result /= 1.0e+308; }else{ result = s * scale; result *= 1.0e+308; } }else{ assert( e>=342 ); if( esign<0 ){ result = 0.0*s; }else{ result = 1e308*1e308*s; /* Infinity */ } } }else{ /* 1.0e+22 is the largest power of 10 than can be ** represented exactly. */ while( e%22 ) { scale *= 1.0e+1; e -= 1; } while( e>0 ) { scale *= 1.0e+22; e -= 22; } if( esign<0 ){ result = s / scale; }else{ result = s * scale; } } } } /* store the result */ *pResult = result; /* return true if number and no extra non-whitespace chracters after */ return z==zEnd && nDigits>0 && eValid && nonNum==0; #else return !sqlite3Atoi64(z, pResult, length, enc); #endif /* SQLITE_OMIT_FLOATING_POINT */ } /* ** Compare the 19-character string zNum against the text representation |