AN910 datasheet(49/51 Pages) STMICROELECTRONICS

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ST7 AND ST9 PERFORMANCE BENCHMARKING

Table 15. Full set of tests

9.2.2 Memory considerations

The “place” of the memory (internal or external) of the MCU used for stack, has indirectly

a consequence on the results. As all the MCUs own internal memory and do not own external

memory, internal memory has been used for most of the tests. But because some tests

(especially Ackermann function) require an important stack capacity, alternative solutions

have been elaborated.

Here is a synthesis of the different cases:

• for tests with a limited memory need, internal memory has been used as stack

• for tests with important memory need,

- for MCUs with important internal memory available, internal memory has been used

- for MCUs with limited internal memory but with external memory (with identical access time)

available, external memory has been used

- for MCUs with limited internal memory and external memory with longer access time, no real

measure has been made in order not to disfavour some MCUs; in some of these cases,

theoretical measures have been calculated based on the assembly code - note that

theoretical results are closed to practical results with internal memory

A small number of tests for some MCUs could not have been implemented due to various

reasons.

Tests concerned

string, char, bubble(10 words), blkmov(64 bytes), convert, 16mul, shright, bitrst

sieve, acker(3,5), acker(3,6), bubble(600 words), blkmov(512 bytes)

Resulting ratio formulas

ET = execution time

CS = code size

sum(ET ratios of full set)

Global ET ratio for full set =

number of tests of full set

sum(CS ratios of full set)

Global CS ratio for full set =

number of tests of full set

AN910 データシート(PDF) 49 Page - STMicroelectronics