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

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.

Introduction (2) 3

Introduction (3) Program compaction methods without decompression can be used in the real-time systems, because they practically don’t increase program execution time. The existing methods with decompression can’t 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

Method Description 5

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

Determining execution frequency of programs basic blocks 7

Determining execution frequency of programs basic blocks (2) 8

The algorithm for evaluation basic block execution frequency 9

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

Determining infrequently executed code 11

Determining infrequently executed code (2) 12

Determining infrequently executed code (3) 13

Method application 14

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

Method implementation (2) 16

17

18

19 Thanks for attention!