ParagonIE_Sodium_Core_Curve25519::ge_double_scalarmult_vartime( string $a, ParagonIE_Sodium_Core_Curve25519_Ge_P3 $A, string $b ): ParagonIE_Sodium_Core_Curve25519_Ge_P2

1760    public static function ge_double_scalarmult_vartime(1761        $a,1762        ParagonIE_Sodium_Core_Curve25519_Ge_P3 $A,1763        $b1764    ) {1765        /** @var array<int, ParagonIE_Sodium_Core_Curve25519_Ge_Cached> $Ai */1766        $Ai = array();1767 1768        /** @var array<int, ParagonIE_Sodium_Core_Curve25519_Ge_Precomp> $Bi */1769        static $Bi = array();1770        if (!$Bi) {1771            for ($i = 0; $i < 8; ++$i) {1772                $Bi[$i] = new ParagonIE_Sodium_Core_Curve25519_Ge_Precomp(1773                    ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(self::$base2[$i][0]),1774                    ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(self::$base2[$i][1]),1775                    ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(self::$base2[$i][2])1776                );1777            }1778        }1779        for ($i = 0; $i < 8; ++$i) {1780            $Ai[$i] = new ParagonIE_Sodium_Core_Curve25519_Ge_Cached(1781                self::fe_0(),1782                self::fe_0(),1783                self::fe_0(),1784                self::fe_0()1785            );1786        }1787 1788        # slide(aslide,a);1789        # slide(bslide,b);1790        /** @var array<int, int> $aslide */1791        $aslide = self::slide($a);1792        /** @var array<int, int> $bslide */1793        $bslide = self::slide($b);1794 1795        # ge_p3_to_cached(&Ai[0],A);1796        # ge_p3_dbl(&t,A); ge_p1p1_to_p3(&A2,&t);1797        $Ai[0] = self::ge_p3_to_cached($A);1798        $t = self::ge_p3_dbl($A);1799        $A2 = self::ge_p1p1_to_p3($t);1800 1801        # ge_add(&t,&A2,&Ai[0]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[1],&u);1802        # ge_add(&t,&A2,&Ai[1]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[2],&u);1803        # ge_add(&t,&A2,&Ai[2]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[3],&u);1804        # ge_add(&t,&A2,&Ai[3]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[4],&u);1805        # ge_add(&t,&A2,&Ai[4]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[5],&u);1806        # ge_add(&t,&A2,&Ai[5]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[6],&u);1807        # ge_add(&t,&A2,&Ai[6]); ge_p1p1_to_p3(&u,&t); ge_p3_to_cached(&Ai[7],&u);1808        for ($i = 0; $i < 7; ++$i) {1809            $t = self::ge_add($A2, $Ai[$i]);1810            $u = self::ge_p1p1_to_p3($t);1811            $Ai[$i + 1] = self::ge_p3_to_cached($u);1812        }1813 1814        # ge_p2_0(r);1815        $r = self::ge_p2_0();1816 1817        # for (i = 255;i >= 0;--i) {1818        #     if (aslide[i] || bslide[i]) break;1819        # }1820        $i = 255;1821        for (; $i >= 0; --$i) {1822            if ($aslide[$i] || $bslide[$i]) {1823                break;1824            }1825        }1826 1827        # for (;i >= 0;--i) {1828        for (; $i >= 0; --$i) {1829            # ge_p2_dbl(&t,r);1830            $t = self::ge_p2_dbl($r);1831 1832            # if (aslide[i] > 0) {1833            if ($aslide[$i] > 0) {1834                # ge_p1p1_to_p3(&u,&t);1835                # ge_add(&t,&u,&Ai[aslide[i]/2]);1836                $u = self::ge_p1p1_to_p3($t);1837                $t = self::ge_add(1838                    $u,1839                    $Ai[(int) floor($aslide[$i] / 2)]