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Fix GH-12143: Remove pre round #12260

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Fix GH-12143: Remove pre round #12260

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f49bc54
remove pre-round
SakiTakamachi Sep 21, 2023
7180912
add comment in _php_math_round
SakiTakamachi Sep 21, 2023
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41 changes: 21 additions & 20 deletions ext/standard/math.c
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Original file line number Diff line number Diff line change
Expand Up @@ -169,41 +169,42 @@ static inline double php_round_helper(double value, int mode) {
* mode. For the specifics of the algorithm, see http://wiki.php.net/rfc/rounding
*/
PHPAPI double _php_math_round(double value, int places, int mode) {
double f1, f2;
double f1;
double tmp_value;
int precision_places;
int value_places;

if (!zend_finite(value) || value == 0.0) {
return value;
}

places = places < INT_MIN+1 ? INT_MIN+1 : places;
precision_places = 14 - php_intlog10abs(value);
value_places = -php_intlog10abs(value);

f1 = php_intpow10(abs(places));

/* If the decimal precision guaranteed by FP arithmetic is higher than
the requested places BUT is small enough to make sure a non-zero value
is returned, pre-round the result to the precision */
if (precision_places > places && precision_places - 15 < places) {
int64_t use_precision = precision_places < INT_MIN+1 ? INT_MIN+1 : precision_places;

f2 = php_intpow10(abs((int)use_precision));
if (use_precision >= 0) {
/*
* In order to minimize the influence of errors specific to floating point numbers,
* digits are adjusted to ensure accuracy. Digits adjustment is performed only if
* the location specifies a range that can be represented by floating point numbers.
*/
if (value_places + 16 > places && value_places <= places) {
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I made a mistake here, I'll fix it later

int precision_places = value_places + 14;
double f2 = php_intpow10(abs(precision_places));

if (precision_places >= 0) {
tmp_value = value * f2;
} else {
tmp_value = value / f2;
}
/* preround the result (tmp_value will always be something * 1e14,
thus never larger than 1e15 here) */
tmp_value = php_round_helper(tmp_value, mode);

use_precision = places - precision_places;
int use_precision = places - precision_places;
use_precision = use_precision < INT_MIN+1 ? INT_MIN+1 : use_precision;
/* now correctly move the decimal point */
f2 = php_intpow10(abs((int)use_precision));
/* because places < precision_places */
tmp_value = tmp_value / f2;
f2 = php_intpow10(abs(use_precision));

if (use_precision >= 0) {
tmp_value = tmp_value * f2;
} else {
tmp_value = tmp_value / f2;
}
} else {
/* adjust the value */
if (places >= 0) {
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74 changes: 60 additions & 14 deletions ext/standard/tests/math/bug24142.phpt
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Expand Up @@ -2,19 +2,65 @@
Bug #24142 (round() problems)
--FILE--
<?php
$v = 0.005;
for ($i = 1; $i < 10; $i++) {
echo "round({$v}, 2) -> ".round($v, 2)."\n";
$v += 0.01;
}
echo "round(0.005, 2)\n";
var_dump(round(0.005, 2));
echo "\n";

echo "round(0.015, 2)\n";
var_dump(round(0.015, 2));
echo "\n";

echo "round(0.025, 2)\n";
var_dump(round(0.025, 2));
echo "\n";

echo "round(0.035, 2)\n";
var_dump(round(0.035, 2));
echo "\n";

echo "round(0.045, 2)\n";
var_dump(round(0.045, 2));
echo "\n";

echo "round(0.055, 2)\n";
var_dump(round(0.055, 2));
echo "\n";

echo "round(0.065, 2)\n";
var_dump(round(0.065, 2));
echo "\n";

echo "round(0.075, 2)\n";
var_dump(round(0.075, 2));
echo "\n";

echo "round(0.085, 2)\n";
var_dump(round(0.085, 2));
?>
--EXPECT--
round(0.005, 2) -> 0.01
round(0.015, 2) -> 0.02
round(0.025, 2) -> 0.03
round(0.035, 2) -> 0.04
round(0.045, 2) -> 0.05
round(0.055, 2) -> 0.06
round(0.065, 2) -> 0.07
round(0.075, 2) -> 0.08
round(0.085, 2) -> 0.09
round(0.005, 2)
float(0.01)

round(0.015, 2)
float(0.02)

round(0.025, 2)
float(0.03)

round(0.035, 2)
float(0.04)

round(0.045, 2)
float(0.05)

round(0.055, 2)
float(0.06)

round(0.065, 2)
float(0.07)

round(0.075, 2)
float(0.08)

round(0.085, 2)
float(0.09)
75 changes: 75 additions & 0 deletions ext/standard/tests/math/round_gh12143_remove_pre_round.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,75 @@
--TEST--
Fix GH-12143: Remove pre round
--FILE--
<?php
echo "HALF_UP\n";
var_dump(round(1.700000000000145, 13, PHP_ROUND_HALF_UP));
var_dump(round(-1.700000000000145, 13, PHP_ROUND_HALF_UP));
var_dump(round(123456789012344.5, -1, PHP_ROUND_HALF_UP));
var_dump(round(-123456789012344.5, -1, PHP_ROUND_HALF_UP));
echo "\n";

echo "HALF_DOWN\n";
var_dump(round(1.70000000000015, 13, PHP_ROUND_HALF_DOWN));
var_dump(round(-1.70000000000015, 13, PHP_ROUND_HALF_DOWN));
var_dump(round(123456789012345.0, -1, PHP_ROUND_HALF_DOWN));
var_dump(round(-123456789012345.0, -1, PHP_ROUND_HALF_DOWN));
var_dump(round(1.500000000000001, 0, PHP_ROUND_HALF_DOWN));
var_dump(round(-1.500000000000001, 0, PHP_ROUND_HALF_DOWN));
echo "\n";

echo "HALF_EVEN\n";
var_dump(round(1.70000000000025, 13, PHP_ROUND_HALF_EVEN));
var_dump(round(-1.70000000000025, 13, PHP_ROUND_HALF_EVEN));
var_dump(round(1.70000000000075, 13, PHP_ROUND_HALF_EVEN));
var_dump(round(-1.70000000000075, 13, PHP_ROUND_HALF_EVEN));
var_dump(round(12345678901234.5, 0, PHP_ROUND_HALF_EVEN));
var_dump(round(-12345678901234.5, 0, PHP_ROUND_HALF_EVEN));
var_dump(round(1.500000000000001, 0, PHP_ROUND_HALF_EVEN));
var_dump(round(-1.500000000000001, 0, PHP_ROUND_HALF_EVEN));
echo "\n";

echo "HALF_ODD\n";
var_dump(round(1.70000000000025, 13, PHP_ROUND_HALF_ODD));
var_dump(round(-1.70000000000025, 13, PHP_ROUND_HALF_ODD));
var_dump(round(1.70000000000075, 13, PHP_ROUND_HALF_ODD));
var_dump(round(-1.70000000000075, 13, PHP_ROUND_HALF_ODD));
var_dump(round(12345678901233.5, 0, PHP_ROUND_HALF_ODD));
var_dump(round(-12345678901233.5, 0, PHP_ROUND_HALF_ODD));
var_dump(round(1.500000000000001, 0, PHP_ROUND_HALF_ODD));
var_dump(round(-1.500000000000001, 0, PHP_ROUND_HALF_ODD));
?>
--EXPECT--
HALF_UP
float(1.7000000000001)
float(-1.7000000000001)
float(123456789012340)
float(-123456789012340)

HALF_DOWN
float(1.7000000000001)
float(-1.7000000000001)
float(123456789012340)
float(-123456789012340)
float(2)
float(-2)

HALF_EVEN
float(1.7000000000002)
float(-1.7000000000002)
float(1.7000000000008)
float(-1.7000000000008)
float(12345678901234)
float(-12345678901234)
float(2)
float(-2)

HALF_ODD
float(1.7000000000003)
float(-1.7000000000003)
float(1.7000000000007)
float(-1.7000000000007)
float(12345678901233)
float(-12345678901233)
float(2)
float(-2)