if r.lo != 0x19 || r.hi != 0 {
		t.Errorf("lo-range wide mult failed, got %d + %d*(2**64)", r.lo, r.hi)
	}

	a = uint64(18014398509481983) // 2^54 - 1
	b = uint64(18014398509481983) // 2^54 - 1
	r = mul64(a, b)
	if r.lo != 0xff80000000000001 || r.hi != 0xfffffffffff {
		t.Errorf("hi-range wide mult failed, got %d + %d*(2**64)", r.lo, r.hi)
	}

	a = uint64(1125899906842661)
	b = uint64(2097155)

	}
	em = testMetrics{
		free:      254,
		used:      0,
		allocated: 2,
		errors:    2,
	}
	expectMetrics(t, cidrIPv4, em)

	// allocate 264 addresses for each allocator
	// the full range and 10 more (254 + 10 = 264) for IPv4
	for i := 0; i < 264; i++ {
		a.AllocateNext()
		b.AllocateNext()
	}
	em = testMetrics{
		free:      0,
		used:      254,

        result += aHi * bLo; // aHi * bLo < 2^63, result < 2^64
        if (result < 0) {
          result = UnsignedLongs.remainder(result, m);
        }
        // result < 2^63 again
        result += aLo * bHi; // aLo * bHi < 2^63, result < 2^64
        result = times2ToThe32Mod(result, m); // result < m < 2^63
        return plusMod(result, UnsignedLongs.remainder(aLo * bLo /* < 2^64 */, m), m);
      }

      @Override

	SYS_ARCH_SPECIFIC_SYSCALL   = 244
	SYS_WAIT4                   = 260
	SYS_PRLIMIT64               = 261
	SYS_FANOTIFY_INIT           = 262
	SYS_FANOTIFY_MARK           = 263
	SYS_NAME_TO_HANDLE_AT       = 264
	SYS_OPEN_BY_HANDLE_AT       = 265
	SYS_CLOCK_ADJTIME           = 266
	SYS_SYNCFS                  = 267
	SYS_SETNS                   = 268
	SYS_SENDMMSG                = 269
	SYS_PROCESS_VM_READV        = 270

	}
	em = testMetrics{
		free:      254,
		used:      0,
		allocated: 2,
		errors:    2,
	}
	expectMetrics(t, cidrIPv4, em)

	// allocate 264 addresses for each allocator
	// the full range and 10 more (254 + 10 = 264) for IPv4
	for i := 0; i < 264; i++ {
		a.AllocateNext()
		b.AllocateNext()
	}
	em = testMetrics{
		free:      0,
		used:      254,

        result += aHi * bLo; // aHi * bLo < 2^63, result < 2^64
        if (result < 0) {
          result = UnsignedLongs.remainder(result, m);
        }
        // result < 2^63 again
        result += aLo * bHi; // aLo * bHi < 2^63, result < 2^64
        result = times2ToThe32Mod(result, m); // result < m < 2^63
        return plusMod(result, UnsignedLongs.remainder(aLo * bLo /* < 2^64 */, m), m);
      }

      @Override

	SYS_ARCH_SPECIFIC_SYSCALL   = 244
	SYS_WAIT4                   = 260
	SYS_PRLIMIT64               = 261
	SYS_FANOTIFY_INIT           = 262
	SYS_FANOTIFY_MARK           = 263
	SYS_NAME_TO_HANDLE_AT       = 264
	SYS_OPEN_BY_HANDLE_AT       = 265
	SYS_CLOCK_ADJTIME           = 266
	SYS_SYNCFS                  = 267
	SYS_SETNS                   = 268
	SYS_SENDMMSG                = 269
	SYS_PROCESS_VM_READV        = 270

}

// duration computes the difference between now and the start time stored in the stamp.
//
// Returns 0 if the difference is negative, which may happen if now is stale or if the
// before and after timestamps cross a 2^(64-limiterEventBits) boundary.
func (s limiterEventStamp) duration(now int64) int64 {
	// The top limiterEventBits bits of the timestamp are derived from the current time
	// when computing a duration.

	SYS_RISCV_FLUSH_ICACHE      = 259
	SYS_WAIT4                   = 260
	SYS_PRLIMIT64               = 261
	SYS_FANOTIFY_INIT           = 262
	SYS_FANOTIFY_MARK           = 263
	SYS_NAME_TO_HANDLE_AT       = 264
	SYS_OPEN_BY_HANDLE_AT       = 265
	SYS_CLOCK_ADJTIME           = 266
	SYS_SYNCFS                  = 267
	SYS_SETNS                   = 268
	SYS_SENDMMSG                = 269
	SYS_PROCESS_VM_READV        = 270

	SYS_MKNODAT                 = 259
	SYS_FCHOWNAT                = 260
	SYS_FUTIMESAT               = 261
	SYS_NEWFSTATAT              = 262
	SYS_UNLINKAT                = 263
	SYS_RENAMEAT                = 264
	SYS_LINKAT                  = 265
	SYS_SYMLINKAT               = 266
	SYS_READLINKAT              = 267
	SYS_FCHMODAT                = 268
	SYS_FACCESSAT               = 269
	SYS_PSELECT6                = 270