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ST7 AND ST9 PERFORMANCE BENCHMARKING

8 DESCRIPTION OF THE TEST ROUTINES

This section is a more precise description of the test routines. For each test, are detailed the

algorithm, its implementation and the features which it stresses.

8.1 ERATOSTHENES SIEVE

8.2 ACKERMANN FUNCTION

8.3 STRING SEARCH

Algorithm

The Eratosthenes sieve is a well-known algorithm which searches the prime numbers greater

than or equal 3 out of n elements (n=8189 has been chosen arbitrary).

Implementation

The even numbers greater than 3 are not prime numbers, so that this algorithm only looks for

prime numbers among an array of odd numbers.

We have chosen an array of 8189 elements. It represents the odd numbers from 3 to 16379. The

array is initialized with the value 'true' ('true' = 0), and is then filled with 1 (false) if the

corresponding number is not a prime number or is not modified (it keeps the value 0='true') if it

is a prime number. Don't forget that it is an array of odd numbers: array[j]

↔ 2j+3

At the beginning of the routine, each number is a potential prime number (initialization value is

'true'). The algorithm consists in setting (to 'false') the odd multiples of every prime number found

in the array skimmed through in the ascending order.

Features stressed

This test measures the elementary computational capability and the ability to manipulate

data in an array.

Algorithm

The Ackermann function is a two parameter function -acker(m,n)- which induces several

recursive calls.

Implementation

This test routine is performed with two different pairs of parameters: acker(3,5) and acker(3,6).

For instance, with the parameters m=3 and n=6, the function induces 172, 233 procedure calls.

Features stressed

It tests the efficiency in recursive procedure calls and in stacks usage.

Algorithm

The String search consists in searching a 16-byte string in a 128-character array.

Implementation

The data are predefined with the following contents:

for the 128-character array,

“xxxxxxxxpatterxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx” (64 bytes)

“xxxxxxxxxxxxxxxxxpattern is here!xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx” (64 bytes)

and for the 16-byte string,

“pattern is here!” (16 bytes)

The searching algorithm looks for the first matching character in the array and then compares

the rest of the string. If the searched string has been found, it returns the address of the first

character of the string in the array.

Features stressed

This program measures the efficiency in data comparison and string manipulation.

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