33 lines
834 B
PHP
33 lines
834 B
PHP
--TEST--
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Bug #75170: mt_rand() bias on 64-bit machines
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--CREDITS--
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Solar Designer in https://externals.io/message/100229
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--FILE--
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<?php
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// PHP pre-7.1.0 modulo bias
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mt_srand(1234567890);
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$total = 10000;
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$max = 0x66666666;
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$halves[0] = $halves[1] = 0;
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for ($i = 0; $i < $total; $i++) {
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$halves[(mt_rand(0, $max - 1) >> 1) & 1]++;
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}
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printf("%.1f%% vs. %.1f%%\n", 100. * $halves[0] / $total, 100. * $halves[1] / $total);
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// PHP 7.1.0 to 7.2.0beta2 modulo bias bug found during work
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// on http://www.openwall.com/php_mt_seed/
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mt_srand(1234567890);
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$total = 10000;
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$max = 0x66666666;
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$halves[0] = $halves[1] = 0;
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for ($i = 0; $i < $total; $i++) {
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$halves[mt_rand(0, $max - 1) / ($max / 2)]++;
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}
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printf("%.1f%% vs. %.1f%%\n", 100. * $halves[0] / $total, 100. * $halves[1] / $total);
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?>
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--EXPECT--
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49.5% vs. 50.5%
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50.5% vs. 49.5%
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