AN910 Datasheet, PDF (49/51 Pages) STMicroelectronics – ST7 AND ST9 PERFORMANCE BENCHMARKING

ST7 AND ST9 PERFORMANCE BENCHMARKING
Table 15. Full set of tests
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
Global ET ratio for full set =
Global CS ratio for full set =
sum(ET ratios of full set)
number of tests of full set
sum(CS ratios of full set)
number of tests of full set
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.
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