4.6. Network Exploration

In order to add a bus to the design, users click the button Add to pop up the Bus Selection dialog which opens and loads the bus database and allows users to select an additional bus out of the bus database. The Bus Selection dialog is shown in Figure 4-21.

At the left of the Bus Selection dialog is a bus category table. Each row represents one category of busses in the database. For example, row Standard contains all the standard busses in the database.

By clicking and selecting one row in the table at left, users will be shown all the busses in the selected category in the table at the right. Each row of the table at the right represents one type of bus in the database under the selected category. The name of the bus type is displayed in the Bus column. The Link, Mem, Intr and Queue columns show the features of the bus, i.e. whether the bus supports link (packet/message) and/or memory (shared variable accesses or memory-mapped I/O) type transfers (optionally showing the number of supported transfer modes each), whether the bus provides interrupts for synchronization (marked with an `X' if synchronization is built into the bus) and whether the bus has queue semantics (with bus-internal buffers), respectively. Finally, other attributes of the bus type are displayed in separate columns. Users can select the desired bus type by clicking the corresponding row.

There are two buttons at the bottom of the Bus Selection dialog: Ok and Cancel. By clicking the Ok button, an additional bus of the selected bus type and with an automatically determined name is added into the design's allocated network architecture. In addition, busses can be allocated by double-clicking into the desired bus type row in the Bus Selection dialog (equivalent to selecting the row and pressing Ok). Clicking the Cancel button aborts and cancels Bus selection without changes to the bus allocation. Either clicking Ok or Cancel button will close the Bus Selection dialog and return to the Network Allocation dialog.

Components in the database can be parametrizable during instantiation. For such components, their type is shown in italic letters in the Component column. Furthermore, when allocating such a parametrizable component (by pressing the Ok button or by double-clicking on the component), a Component Parameter dialog will be popped up (see Figure 4-18 in Section 4.5.1). In this dialog, the user has to enter and confirm all parameters for the given component instance to be allocated. Users can enter any value for any parameter (within the value range allowed by the component) by clicking into each parameter's value field in the dialog. Clicking the Ok button of the dialog will generate a new customized component type with the selected parameters and will then allocate a new instance of this parametrized type. Clicking the Cancel button aborts component parametrization and returns to the Bus Selection dialog.

In order to duplicate an existing bus in the design's bus allocation, users can select a bus by clicking the corresponding row in the allocation table and click the button Copy. Clicking Copy will add a new bus instance with an automatically determined name and with the same type, attributes and description as the currently selected bus to the design's allocation.

In order to remove a bus from the design's allocation, users can select the target bus to be removed in the allocation table and click the Remove button. Clicking Remove will remove the selected bus from the list of allocated busses. Busses that currently have PEs or CEs connected to them will not be available for deletion (the Remove button will be inactive and grayed out for them).

Users can edit the bus name and bus description in the bus allocation tab by clicking into the respective Name or Description column of the corresponding bus. Clicking into any of these cells will allow editing of the respective text in the cell by opening a text edit box in place. Pressing the Esc key during editing aborts the edit operation. Pressing Enter accepts the entered text and changes the bus name or description in the allocation accordingly.

Users can view the parameters assigned for parameterized components by clicking on the Parameters... button in the Bus Allocation dialog after a component has been allocated. In this view, parameters are read-only and are uneditable. Clicking the Ok button closes the dialog.

In order to add a CE to the design, users click the button Add to pop up the CE Selection dialog which opens and loads the CE database and allows users to select an additional CE out of the CE database. The CE Selection dialog is shown in Figure 4-23.

At the left of the CE Selection dialog is a CE category table. Each row represents one category of CEs in the database. For example, row Transducer contains all the transducers in the database.

By clicking and selecting one row in the table at left, users will be shown all the CEs in the selected category in the table at the right. Each row of the table at the right represents one type of CE in the database under the selected category. The name of the CE type is displayed in the Component column. The Bridge column shows the features of the CE, i.e. whether the CE is a bridge (is capable of bus bridging at the lowest, protocol level). Finally, other attributes of the CE type are displayed in separate columns. Users can select the desired CE type by clicking the corresponding row.

There are two buttons at the bottom of the CE Selection dialog: Ok and Cancel. By clicking the Ok button, an additional CE of the selected CE type and with an automatically determined name is added into the design's allocated network architecture. In addition, CEs can be allocated by double-clicking into the desired CE type row in the CE Selection dialog (equivalent to selecting the row and pressing Ok). Clicking the Cancel button aborts and cancels CE selection without changes to the CE allocation. Either clicking Ok or Cancel button will close the CE Selection dialog and return to the Network Allocation dialog.

Components in the database can be parametrizable during instantiation. For such components, their type is shown in italic letters in the Component column. Furthermore, when allocating such a parametrizable component (by pressing the Ok button or by double-clicking on the component), a Component Parameter dialog will be popped up (see Figure 4-18 in Section 4.5.1). In this dialog, the user has to enter and confirm all parameters for the given component instance to be allocated. Users can enter any value for any parameter (within the value range allowed by the component) by clicking into each parameter's value field in the dialog. Clicking the Ok button of the dialog will generate a new customized component type with the selected parameters and will then allocate a new instance of this parametrized type. Clicking the Cancel button aborts component parametrization and returns to the CE Selection dialog.

In order to duplicate an existing CE in the design's CE allocation, users can select a CE by clicking the corresponding row in the allocation table and click the button Copy. Clicking Copy will add a new CE instance with an automatically determined name and with the same type, attributes and description as the currently selected CE to the design's allocation.

In order to remove a CE from the design's allocation, users can select the target CE to be removed in the allocation table and click the Remove button. Clicking Remove will remove the selected CE from the list of allocated busses.

Users can edit the CE name and CE description in the CE allocation tab by clicking into the respective Name or Description column of the corresponding CE. Clicking into any of these cells will allow editing of the respective text in the cell by opening a text edit box in place. Pressing the Esc key during editing aborts the edit operation. Pressing Enter accepts the entered text and changes the CE name or description in the allocation accordingly.

Users can view the parameters assigned for parameterized components by clicking on the Parameters... button in the CE Allocation dialog after a component has been allocated. In this view, parameters are read-only and are uneditable. Clicking the Ok button closes the dialog.

The list of ports/interfaces for each PE and CE is determined by the list of available ports defined by the PE/CE database model. For synthesizable PEs/CEs with undefined or variable port lists in the database, the user can add or remove ports from the PE's or CE's port list. Right-clicking onto a PE's or CE's port list or port will pop up a context menu with the following entries:

In the table, the users can then connect ports of a PEs/CEs to busses by clicking into the corresponding table cell at the intersection of the port and bus. If the selected port is already connected to a different bus, the connection will be moved (i.e. the previous connection be removed and the port re-connected to the new bus). Ports with pre-defined, fixed protocols can only be connected to matching busses and clicking into any other bus row will have no effect. Pre-connected ports with mandatory, pre-defined and fixed bus connections can not be connected to any other bus, i.e. clicking into any row will have no effect.

For each port connection, the user can further specify the interface type of the port. Generally, ports can connected to busses either as bus master, bus slave or as combined bus master/slave. If the bus from the database supports arbitration and allows for multiple masters on the bus, any master connection must also specify the arbiter port to use where the bus database model defines the set of possible master ports supported by the bus. If the bus only supports interrupts but no regular masters or slaves, special connections ``wait'' and ``notify'' (optionally suffixed by the index of the selected interrupt bank/protocol) are available to connect a port on the bus' interrupt master (detection) and/or slave (generation) side, respectively.

Clicking into a valid (see above) connection cell of the connectivity matrix will open a drop-down combo box in that cell in place with entries for all possible connection types for that port/bus combination. In general, users will be able to choose in the combo box from the following connection types: slave, name of any available (not connected to any other PE/CE port) bus master port, or any combination of slave with any available master port. Selecting an entry from the combo box will change the connection type and update the text displayed in the cell accordingly.

If the bus contains more than one protocol, multiple connections may be allowed to that bus via the same port. In Figure 4-24, CE0 connects from MBus to Bus1 at ProtocolA and ProtocolB as ``master'' and ``master2'', respectively. If the user makes a new connection with a different bus, all previous connections with other busses will be removed automatically.

Every slave connected to a system bus can be assigned a slave address range each. Base addresses and address masks define the address space occupied by the slave on the bus, i.e. they define the address decoding to be performed for that slave. Note that address ranges will later be used for automatic address selection during bus parameter assignment (see Section 4.7.1). Address ranges assigned to each slave on a bus are shown in the form of a tool tip when hovering over the corresponding bus connection. If addresses of two more more slaves on the same bus overlap, their connections will be highlighted (using red text color) in the connectivity matrix.

All slave connections are automatically pre-assigned with default address ranges based on the bus characteristics and slave requirements. Busses define the overall range of possible bus addresses and they optionally restrict the addresses available for each specific slave connection. In general, during pre-assignment the bus address space is divided evenly among the slaves and slaves can only be assigned base addresses for which the lower half of the bus address bits are zero. PE or CE ports with pre-defined, fixed addresses will be automatically assigned corresponding fixed slave address ranges on the bus. For such ports, slave address ranges on the bus can not be modified by the user.

In the table, users can assign base address to each connection of slave type. For combined master/slave connections, base addresses will only apply to the slave side. Connections that are only master on the bus are not allowed to get any address assigned. In all cases, the slave's address mask is automatically computed from the entered base address such that the largest, non-overlapping range is obtained. Right-clicking onto a cell of the connectivity matrix will pop up a context menu with the following entries:

which automatically groups and merges sequentially accesses channels over one shared channel.

which generates implementations of the presentation layer inside PEs for conversion of abstract data types into network bytes.

which inserts communication elements such as transducers and bridges between PEs and generates necessary additional network protocol implementations inside PEs and CEs.

which automatically flattens the complete network protocol stack and which performs code fusion to interleave data type conversions with data transfers in order to reduce PE-internal buffer requirements and produce bus-word optimized packeting of data.

which, instead of a tight packing of byte-aligned data (for minimal message size), aligns individual data elements in a message along bus word boundaries and using PE-internal data alignment in order to produce efficient and aligned data conversion and data transfer code optimized for the given PE (at the expense of larger messages and potentially more bus traffic).

which, in order to reduce synchronization resource requirements, automatically packs and merges subsequent transfers into one large message if message transfers directly follow each other over a given channel.