dx, dy := r.Dx(), r.Dy()
	d0 := dst.PixOffset(r.Min.X, r.Min.Y)
	s0 := src.PixOffset(sp.X, sp.Y)
	var (
		ddelta, sdelta int
		i0, i1, idelta int
	)
	if r.Min.Y < sp.Y || r.Min.Y == sp.Y && r.Min.X <= sp.X {
		ddelta = dst.Stride
		sdelta = src.Stride
		i0, i1, idelta = 0, dx*4, +4
	} else {
		// If the source start point is higher than the destination start point, or equal height but to the left,

func (t *LineTable) step(p *[]byte, pc *uint64, val *int32, first bool) bool {
	uvdelta := t.readvarint(p)
	if uvdelta == 0 && !first {
		return false
	}
	if uvdelta&1 != 0 {
		uvdelta = ^(uvdelta >> 1)
	} else {
		uvdelta >>= 1
	}
	vdelta := int32(uvdelta)
	pcdelta := t.readvarint(p) * t.quantum
	*pc += uint64(pcdelta)
	*val += vdelta
	return true
}

        // Evaluate at positive delta.
        x_data_flat(r) = v + x_delta;
        std::vector<Tensor> y_pos;
        TF_RETURN_IF_ERROR(EvaluateGraph(&session, xs, ys, x_datas, &y_pos));
        // Evaluate at negative delta.
        x_data_flat(r) = v - x_delta;
        std::vector<Tensor> y_neg;
        TF_RETURN_IF_ERROR(EvaluateGraph(&session, xs, ys, x_datas, &y_neg));

      m.size += patch ? 0 : operations_[m.op_index - shift].alloc;
      // deltas is sorted by location; apply any corrections to the current
      // operator.
      for (; idelta != deltas.end() && idelta->op_index == m.op_index;
           ++idelta) {
        m.size += idelta->size;
      }
      mapper(m);
      m.size -= patch ? 0 : operations_[m.op_index - shift].dealloc;
    }
  }

  std::vector<Operation> operations_;

		if dbg {
			ctxt.Logf("%6x %6d %v\n", uint64(p.Pc), val, p)
		}

		if started {
			pcdelta := (p.Pc - pc) / int64(ctxt.Arch.MinLC)
			n := binary.PutUvarint(buf, uint64(pcdelta))
			dst = append(dst, buf[:n]...)
			pc = p.Pc
		}

		delta := val - oldval
		n := binary.PutVarint(buf, int64(delta))
		dst = append(dst, buf[:n]...)
		oldval = val
		started = true

							if err != nil {
								return err
							}
							if value > 16 {
								return UnsupportedError("excessive DC component")
							}
							dcDelta, err := d.receiveExtend(value)
							if err != nil {
								return err
							}
							dc[compIndex] += dcDelta
							b[0] = dc[compIndex] << al
						}

						if zig <= zigEnd && d.eobRun > 0 {
							d.eobRun--
						} else {

		f2(c, x)
	}
}

func f1(c chan []byte, start int64) {
	for x := range c {
		if delta := inuse() - start; delta < 9<<20 {
			println("BUG: f1: after alloc: expected delta at least 9MB, got: ", delta)
			println(x)
		}
		x = nil
		if delta := inuse() - start; delta > 1<<20 {
			println("BUG: f1: after alloc: expected delta below 1MB, got: ", delta)
			println(x)
		}
	}
}

func f2(c chan []byte, start int64) {
	for {

		before int32
		i      int32
		after  int32
	}
	x.before = magic32
	x.after = magic32
	var j int32
	for delta := int32(1); delta+delta > delta; delta += delta {
		k := SwapInt32(&x.i, delta)
		if x.i != delta || k != j {
			t.Fatalf("delta=%d i=%d j=%d k=%d", delta, x.i, j, k)
		}
		j = delta
	}
	if x.before != magic32 || x.after != magic32 {

	// then any Add with positive delta will return error.
	wait bool
}

// Add adds delta, which may be negative, similar to sync.WaitGroup.
// If Add with a positive delta happens after Wait, it will return error,
// which prevent unsafe Add.
func (wg *SafeWaitGroup) Add(delta int) error {
	wg.mu.RLock()
	defer wg.mu.RUnlock()
	if wg.wait && delta > 0 {

  }

  /** Returns a new bias. */
  private fun adapt(
    delta: Int,
    numpoints: Int,
    first: Boolean,
  ): Int {
    var delta =
      when {
        first -> delta / DAMP
        else -> delta / 2
      }
    delta += (delta / numpoints)
    var k = 0
    while (delta > ((BASE - TMIN) * TMAX) / 2) {
      delta /= (BASE - TMIN)
      k += BASE
    }