- boog [-hmxold] input_file output_file [lax_file]
boog is a mapper of a behavioural description onto a predefined standard cell library as SXLIB. It is the second step of the logic synthesis: it builds a gate network using a standard cell library.
Input file description
The logic level behavioural description (.vbe file) uses the same VHDL subset as the logic simulator asimut, the FSM synthesizer syf, the functional abstractor yagle and the formal prover proof (for further information about the subset of VHDL, see the "vbe" manual).
Some constraints due to hardware mapping exist. These attributes are only supported by technology mapping onto a standard cell library as sxlib.
For the register signal description, only one condition statement must appear. STABLE must be strictely used as a negativ motion and joined to clock setup value. Setup can be on high or low value, but it would be worthy to choose it accordingly with hardware register cell.
label: BLOCK (NOT ck 'STABLE and ck='1')
reg <= GUARDED expr;
You can also put a write enable condition to your register:
label: BLOCK (NOT ck 'STABLE and ck='1' and wen='1')
reg <= GUARDED expr;
A special feature has been introduced in the VHDL subset in order to allow the don't care description for external outputs and internal registers : A bit signal can take the 'd' value. This value is interpreted as a '0' by the logic simulator asimut. Don't Cares are automatically generated by syf in the resulting '.vbe' file.
Output file description
A pure standard cell netlist is produced by boog. This file is destinated for /fBloon/fP alliance utility to improve RC delays. Any equipotential keeps its name from connector to connector. In trouble case, buffers are inserted to respect this VHDL constraint.
lax Parameter file description
The lax file is common with other logic synthesis tools and is used for driving the synthesis process. See lax(5) manual for more detail.
lax uses a lot of parameters to guide every step of the synthesis process. Some parameters are globally used (for example, optimization level whereas others are specifically used (load capacitance for the netlist optimization only). Here is the default lax file (see the user's manual for further information about the syntax of the '.lax' file):
Optimization mode = 2 (50% area - 50% delay)
Input impedance = 0
Output capacitance = 0
Delayed input = none
Auxiliary signal saved = none
Mapping with a standard cell library
Every cell appearing in the directory defined by the environment variable MBK_TARGET_LIB may be used by boog since they are described as a '.vbe' file. There are some restrictions about the type of the cell used. Every cell has to have only one output. The cell must be characterized. The timing and area informations required by boog are specified in the "generic" clause of the ".vbe" file.
- Help mode. Displays possible uses of boog.
- -m optim_mode
- Optimization mode. Can be defined in lax file, it's only a shortcut to define it on command line. This mode number has an array defined between 0 and 4. It indicates the way of optimization the user wants. If 0 is chosen, the circuit area will be improved. On the other hand, 4 will improve circuit delays. 2 is a medium value for optimization.
- -x xsch_mode
- Generate a '.xsc' file. It is a color map for each signals contained in output_file network. This file is used by xsch to view the netlist. By choosing level 0 or 1 for xsch_mode, you can color respectively the critical path or all signals with delay graduation.
- -o output_file
- Just another way to show explicitely the VST output file name.
- -l lax_file
- Just another way to show explicitely the LAX parameter file name.
- -d debug_file
Generates a VBEdebug file. It comes from internal result algorithm. Users aren't concerned.
The following environment variables have to be set before using boog :
MBK_CATA_LIB gives the auxiliary paths of the directories of input files (behavioural description).
MBK_TARGET_LIB gives the path (single) of the directory of the selected standard cell library.
MBK_OUT_LO gives the output format of the structural description.
boog alu alu