Electrical computers and digital processing systems: memory – Storage accessing and control – Memory configuring
Reexamination Certificate
2001-12-21
2003-12-23
Ellis, Kevin L. (Department: 2186)
Electrical computers and digital processing systems: memory
Storage accessing and control
Memory configuring
C711S154000
Reexamination Certificate
active
06668312
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a system for designing and producing an electronic circuit having a desired functionality and comprising both hardware which is dedicated to execution of certain of the functionality and software-controlled machines for executing the remainder of the functionality under the control of suitable software.
BACKGROUND OF THE INVENTION
It is well known that software-controlled machines provide great flexibility in that they can be adapted to many different desired purposes by the use of suitable software. As well as being used in the familiar general purpose computers, software-controlled processors are now used in many products such as cars, telephones and other domestic products, where they are known as embedded systems.
However, for a given a function, a software-controlled processor is usually slower than hardware dedicated to that function. A way of overcoming this problem is to use a special software-controlled processor such as a RISC processor which can be made to function more quickly for limited purposes by having its parameters (for instance size, instruction set etc.) tailored to the desired functionality.
Where hardware is used, though, although it increases the speed of operation, it lacks flexibility and, for instance, although it may be suitable for the task for which it was designed it may not be suitable for a modified version of that task which is desired later. It is now possible to form the hardware on reconfigurable logic circuits, such as Field Programmable Gate Arrays (FPGA's) which are logic circuits which can be repeatedly reconfigured in different ways. Thus they provide the speed advantages of dedicated hardware, with some degree of flexibility for later updating or multiple functionality.
In general, though, it can be seen that designers face a problem in finding the right balance between speed and generality. They can build versatile chips which will be software controlled and thus perform many different functions relatively slowly, or they can devise application-specific chips that do only a limited set of tasks but do them much more quickly.
A compromise solution to these problems can be found in systems which combine both dedicated hardware and also software. The hardware is dedicated to particular functions, e.g. those requiring speed, and the software can perform the remaining functions. The design of such systems is known as hardware-software codesign.
Within the design process, the designer must decide, for a target system with a desired functionality, which functions are to be performed in hardware and which in software. This is known as partitioning the design. Although such systems can be highly effective, the designer must be familiar with both software and hardware design. It would be advantageous if such systems could be designed by people who have familiarity only with software and which could utilize the flexibility of configurable logic resources.
SUMMARY OF THE INVENTION
A system, method and article of manufacture are provided for recording memory transfers required by an executing application. A memory of a system hosting an application is divided into micropages (small ranges of memory). A memory map of the application is maintained. The map records which functions (or groups of functions) have valid copies of micropages. The map is checked to determine which functions have a valid copy of the data when a current function reads for a micropage. Nothing is recorded if the current function has a valid copy of the data. A transfer of the data from another function to the current function is recorded if the current function does not have a valid copy of the data. The map is updated to reflect that the current function has a valid copy of the micropage if the data is transferred from another function. A write to a micropage is recorded. The map is updated to reflect that the current function has the only valid copy of a micropage when a write to the micropage occurs. A report of data transfers among the functions is output.
In one aspect of the present invention, the data is taken as coming from an external source function if no function has a valid copy of the data. The report can be a 2-dimensional table recording data transfers among the functions.
Preferably, an ownership of the micropage is represented by a bitmask, where each bit represents a possible ownership domain. The functions of the application can be partitioned into domains representing hardware and software domains of a target system. Also preferably, external libraries are supported.
REFERENCES:
patent: 5987243 (1999-11-01), Aihara
patent: 6477683 (2002-11-01), Killian et al.
Carlton Fields P.A.
Celoxica Ltd.
Ellis Kevin L.
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