fe_neg example

$h->X = self::fe_mul(
                $h->X,
                ParagonIE_Sodium_Core_Curve25519_Fe::fromArray(self::$sqrtm1)
            );
        }

        # if (fe_isnegative(h->X) == (s[31] >> 7)) {         # fe_neg(h->X,h->X);         # }         $i = self::chrToInt($s[31]);
        if (self::fe_isnegative($h->X) === ($i >> 7)) {
            $h->X = self::fe_neg($h->X);
        }

        # fe_mul(h->T,h->X,h->Y);         $h->T = self::fe_mul($h->X, $h->Y);
        return $h;
    }

    /** * @internal You should not use this directly from another application * * @param ParagonIE_Sodium_Core_Curve25519_Ge_P1p1 $R * @param ParagonIE_Sodium_Core_Curve25519_Ge_P3 $p * @param ParagonIE_Sodium_Core_Curve25519_Ge_Precomp $q * @return ParagonIE_Sodium_Core_Curve25519_Ge_P1p1 */

const HASH_SC_L = 48;
    const CORE_H2C_SHA256 = 1;
    const CORE_H2C_SHA512 = 2;

    /** * @param ParagonIE_Sodium_Core_Curve25519_Fe $f * @param int $b * @return ParagonIE_Sodium_Core_Curve25519_Fe */
    public static function fe_cneg(ParagonIE_Sodium_Core_Curve25519_Fe $f, $b)
    {
        $negf = self::fe_neg($f);
        return self::fe_cmov($f, $negf, $b);
    }

    /** * @param ParagonIE_Sodium_Core_Curve25519_Fe $f * @return ParagonIE_Sodium_Core_Curve25519_Fe * @throws SodiumException */
    public static function fe_abs(ParagonIE_Sodium_Core_Curve25519_Fe $f)
    {
        return self::fe_cneg($f, self::fe_isnegative($f));
    }

$h->X = self::fe_mul(
                $h->X,
                ParagonIE_Sodium_Core32_Curve25519_Fe::fromIntArray(self::$sqrtm1)
            );
        }

        # if (fe_isnegative(h->X) == (s[31] >> 7)) {         # fe_neg(h->X,h->X);         # }         $i = self::chrToInt($s[31]);
        if (self::fe_isnegative($h->X) === ($i >> 7)) {
            $h->X = self::fe_neg($h->X);
        }

        # fe_mul(h->T,h->X,h->Y);         $h->T = self::fe_mul($h->X, $h->Y);
        return $h;
    }

    /** * @internal You should not use this directly from another application * * @param ParagonIE_Sodium_Core32_Curve25519_Ge_P1p1 $R * @param ParagonIE_Sodium_Core32_Curve25519_Ge_P3 $p * @param ParagonIE_Sodium_Core32_Curve25519_Ge_Precomp $q * @return ParagonIE_Sodium_Core32_Curve25519_Ge_P1p1 * @throws SodiumException * @throws TypeError */