AN910 datasheet(48/51 Pages) STMICROELECTRONICS

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ST7 AND ST9 PERFORMANCE BENCHMARKING

9.1.2 Code size measure

Code size is measured with the assembly code. The result is the number of bytes used to

code the test routine (in Test Loop part) without the set and reset instructions for the I/O pin.

Here is an example of a Test Loop:

0000

C290

test:

setb p1.0

; set I/O pin

0002

7809

mov r0, #srcpointer

; beginning of test routine

0004

7982

mov r1, #destpointer

0006

900200

mov dptr, #200h

0009

7F79

mov r7, #121

000B

loop:

mov a, @r0

000C

movc a, @a+dptr

000D

mov @r1, a

000E

inc r0

000F

inc r2

0010

DFF9

djnz r7, loop

; end of test routine

0012

D290

finish:

clr p1.0

; reset I/O pin

0014

ret

The code size of this assembly code equals (12h-2h) = 10h = 16d, thus 16 bytes.

9.2 CALCULATION

9.2.1 Execution time and code size ratios

From execution time and code size measures, preliminary ratios with ST9+ MCU as

reference have been calculated for each test. Using those results, a global execution time

ratio and a global code size ratio have been calculated as an average of all ratios.

As all the tests could not have been implemented on all MCUs (see <Italic>9.2.2 Memory

considerations<Italic end>), one or two different results are presented for each MCU. The

first one, available for all the MCUs, has been calculated with the reduced set of tests

performed on all the MCUs (Table 14). The second one, only available for some MCUs, has

been calculated with the full set of tests (Table 15).

Table 14. Reduced set of tests

Tests concerned

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

Resulting ratio formulas

ET = execution time

CS = code size

sum(ET ratios of reduced set)

Global ET ratio for reduced set =

number of tests of reduced set

sum(CS ratios of reduced set)

Global CS ratio for reduced set =

number of tests of reduced set

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