AN910 Datasheet, PDF (27/51 Pages) STMicroelectronics – ST7 AND ST9 PERFORMANCE BENCHMARKING

ST7 AND ST9 PERFORMANCE BENCHMARKING
7.2.3 Special addressing modes and instructions
Test routines assembly code analysis has pointed out that some addressing modes and
instructions can reduce significantly the code size. To a minor extent, execution time may also
be decreased. The addressing modes and instructions concerned are usually those which
allow to make two operations within a single instruction.
Indirect with pre/post-increment addressing mode is an example. This mode is very useful for
loops and block moves. Modes allowing memory-to-memory transfers are another example
for block moves. In the same way, instructions such as bit test & set, decrement & branch, or
compare & branch have stood out for the same reasons.
These addressing modes and instructions are mentioned in tables as special addressing
modes and special instructions.
7.3 MCU CORE ANALYSIS
The following paragraphs are synthetical diagrams presenting the main parameters of core
architecture for each MCU. Those parameters have been synthesized from the databooks.
Some special characteristics are also mentioned, even if they are not really significant for the
benchmark result analysis.
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