Faster PHP solution.

PrimePHP/solution_2/Dockerfile

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+FROM php:8.3-cli
+
+RUN mv "$PHP_INI_DIR/php.ini-production" "$PHP_INI_DIR/php.ini" && \
+    printf "zend_extension=opcache.so\nopcache.enable=1\nopcache.enable_cli=1\nopcache.jit_buffer_size=100M\nopcache.jit=tracing\nmemory_limit=-1\n" >> "$PHP_INI_DIR/php.ini"
+
+WORKDIR /opt/app
+COPY *.php .
+
+ENTRYPOINT [ "php", "prime_sieve.php" ]

PrimePHP/solution_2/README.md

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+# PHP solution by AndrewTheCoder
+
+![Algorithm](https://img.shields.io/badge/Algorithm-base-green)
+![Faithfulness](https://img.shields.io/badge/Faithful-yes-green)
+![Parallelism](https://img.shields.io/badge/Parallel-no-green)
+![Bit count](https://img.shields.io/badge/Bits-8-yellowgreen)

PrimePHP/solution_2/prime_sieve.php

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+<?php
+
+declare(strict_types=1);
+
+class SieveOfEratosthenes
+{
+  private int $sieve_size;
+  private int $rawbits_size;
+  private string $rawbits;
+
+  public static array $primeCounts = [
+    10 => 4,
+    100 => 25,
+    1000 => 168,
+    10000 => 1229,
+    100000 => 9592,
+    1000000 => 78498,
+    10000000 => 664579,
+    100000000 => 5761455
+  ];
+
+  public function __construct()
+  {
+    $this->sieve_size = 100000;
+    $this->rawbits_size = ($this->sieve_size + 1) >> 1;
+    $this->rawbits = str_pad('', $this->rawbits_size, '0');
+  }
+
+  public function run(): void
+  {
+    $factor = 3;
+    $q = sqrt($this->sieve_size);
+    while ($factor < $q) {
+      for ($i = $factor; $i <= $this->sieve_size; $i += 2) {
+        $rbi = $i >> 1;
+        if ($this->rawbits[$rbi] === '0') {
+          $factor = $i;
+          break;
+        }
+      }
+
+      $ft2 = $factor;
+      $start = ($factor * $factor) >> 1;
+      for ($i = $start; $i < $this->rawbits_size; $i += $ft2) {
+        $this->rawbits[$i] = '1';
+      }
+
+      $factor += 2;
+    }
+  }
+
+  public function get_rawbit_count(): int
+  {
+    return substr_count($this->rawbits, '0');
+  }
+
+  public function print_results(): void
+  {
+    for ($i = 1; $i < $this->sieve_size; $i += 2) {
+      if ($this->rawbits[$i >> 1] === '0') {
+        echo $i . ", ";
+      }
+    }
+  }
+}
+
+$start = microtime(true);
+$passes = 0;
+$sieve_size = 1000000;
+$print_results = false;
+$rawbit_count = 0;
+$run_time = 5;
+
+while (time_diff($start) < $run_time * 1000) {
+  $sieve = new SieveOfEratosthenes();
+  $sieve->run();
+  $passes++;
+}
+
+$rawbit_count = $sieve->get_rawbit_count();
+if ($print_results) {
+  $sieve->print_results();
+  echo "\n";
+}
+
+$td = time_diff($start);
+
+printf(
+  "Passes: %d, Time: %dms, Avg: %dms, Limit: %d, Count: %d, Valid: %s",
+  $passes,
+  (int)$td,
+  $td / $passes,
+  $sieve_size,
+  $rawbit_count,
+  (validate_result($sieve_size) === $rawbit_count) ? 'True' : 'False'
+);
+
+echo "\n\n";
+printf("andrewthecoder;%d;%f;1;algorithm=base,faithful=yes,bits=8\n", $passes, ((float)$td) / 1000);
+
+function time_diff(float $start): float
+{
+  return (microtime(true) - $start) * 1000;
+}
+
+function validate_result($sieve_size): ?int
+{
+  return SieveOfEratosthenes::$primeCounts[$sieve_size];
+}