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The method of program compaction for real-time applications Ruslan L. Smeliansky Lomonosov Moscow State University Faculty of Computational Mathematics and Cybernetics

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2 Introduction Memory Compacted code Original code Program compaction methods - such program transformation that reduces the program code size in memory (memory footprint) with retaining the program functionality. Embedded real-time systems The largest type of computer systems. The memory and energy are the most critical resources.

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Introduction (2) 3

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Introduction (3) Program compaction methods without decompression can be used in the real-time systems, because they practically dont increase program execution time. The existing methods with decompression cant be used in the real-tine systems, because its lead to uncontrolled significant increasing of execution time. It is necessary to create a program compaction method with decompression which would allow us to control the program execution time depending on the compression ratio. 4

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Method Description 5

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Method Details The proposed method is intended to solve the following tasks: Determining execution frequency characteristics of programs behavior; Determining infrequently executed portions of programs. 6

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Determining execution frequency of programs basic blocks 7

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Determining execution frequency of programs basic blocks (2) 8

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The algorithm for evaluation basic block execution frequency 9

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Result of testing of the proposed method SNUDescription minverInverse matrix (size 10x10, values 0-100) 700.04 qsortQuick sort (size 20, values 0-100) 800.08 select10th max elements of an array (size 20, values 0-100) 1000.06 primePrime number (values 0-100000) 900.03 sqrtSquare root (values 0-1000) 300.02 10

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Determining infrequently executed code 11

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Determining infrequently executed code (2) 12

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Determining infrequently executed code (3) 13

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Method application 14

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Method implementation Inputs Program for compression (written on C language). Distributions functions of programs input parameters. The threshold of infrequently executed code. Outputs Compacted program. Files with an offset table and compacted interpreted code. 15

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Method implementation (2) 16

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19 Thanks for attention!