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# Algorithm For Determining Circuit Counts And Input Pins For Logic Blocks

IP.com Disclosure Number: IPCOM000048759D
Original Publication Date: 1982-Mar-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 71K

IBM

## Related People

Rivero, JL: AUTHOR

## Abstract

Design Automation System have the requirement of tracing through a logic block. This function entails the following: 1. Specify the type of block and corresponding output pin. 2. Obtain input pins associated with this output pin. In some cases a need exists for determining how many circuits were encountered when tracing through the logic block. The procedure described herein explains a concise way of storing and retrieving the output to input interconnections and the related number of circuits. An example will be used to explain how the algorithm works.

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Algorithm For Determining Circuit Counts And Input Pins For Logic Blocks

Design Automation System have the requirement of tracing through a logic block. This function entails the following: 1. Specify the type of block and corresponding output pin. 2. Obtain input pins associated with this output pin. In some cases a need exists for determining how many circuits were encountered when tracing through the logic block. The procedure described herein explains a concise way of storing and retrieving the output to input interconnections and the related number of circuits. An example will be used to explain how the algorithm works.

Fig. 1 shows the flow chart for the algorithm. One of the requirements of the program was that the tables describing the Block Functions must be of variable length. This type of table allows for efficient use of computer memory space. However, it may require a complex addressing algorithm. The example in Fig. 2 illustrates how a given Function Table would be addressed by the program.

In Fig. 2A, the Function Array is first read for a match with the Function Name 'ABCD', obtaining the address to the ABCD Function Table. This address is then used to read the table TBLI until the first asterisk (*) is encountered. The asterisk indicates the number of logic blocks that exist in the 'ABCD' logical function. The program then reads each output entry (row of TBL1) until the given output pin is found, and the logic block numbers are then saved. The co...