/** Returns a * b mod m. */
    abstract long mulMod(long a, long b, long m);

    /** Returns a^2 mod m. */
    abstract long squareMod(long a, long m);

    /** Returns a^p mod m. */
    private long powMod(long a, long p, long m) {
      long res = 1;
      for (; p != 0; p >>= 1) {
        if ((p & 1) != 0) {
          res = mulMod(res, a, m);
        }
        a = squareMod(a, m);

	MULLW	$-32769, R8           // c281ffff7fff
	MULLW   $-32769, R8, R9       // 1898c291ffff7fff
	MULLD	$-2147483648, R1      // c21080000000
	MULLD   $-2147483648, R1, R2  // b9040021c22080000000
	MULHD	R9, R8                // b90400b8b98600a9ebb9003f000ab98000b8b90900abebb8003f000ab98000b9b9e9b08a
	MULHD	R7, R2, R1            // b90400b2b98600a7ebb7003f000ab98000b2b90900abebb2003f000ab98000b7b9e9b01a

	BL	4(R4)              // ERROR "non-zero offset"
	ADDF	F0, R1, F2         // ERROR "illegal combination"
	SWI	(R0)               // ERROR "illegal combination"
	MULAD	F0, F1             // ERROR "illegal combination"
	MULAF	F0, F1             // ERROR "illegal combination"
	MULSD	F0, F1             // ERROR "illegal combination"
	MULSF	F0, F1             // ERROR "illegal combination"
	NMULAD	F0, F1             // ERROR "illegal combination"