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AN3350

eTPU specific features

Doc ID 018512 Rev 2

177/185

23.3

eTPU functions structure

eTPU functions have a special structure. An eTPU function consists of several threads. A

thread is executed when the eTPU scheduler assigns execution to it. Using the special

structure the programmer can associate each thread's code with different conditions in the

entry table. The special structure of an eTPU function inludes the following elements:

●

A #pragma ETPU_function declaration.

●

A void function.

●

In the main scope of the function, a series of if()/else statements, each testing one or

more elements of the channel condition see restrictions below.

–

- hsr - Host service request 0..7

–

- lsr - Link service request 0/1

–

- m1 - Match1/Transition2 0/1

–

- m2 - Match2/Transition1 0/1

–

- pin - Input pin 0/1

–

- flag0 0/1

–

- flag1 0/1

The threads code itself resides between these if then elses. Using the conditions the

compiler associates the thread's code with the correct entry points.

A final else (without if) should be present at the end of this structure to collect all the unused

entry points. A warning shall be issued if that else shall be omitted by the user.

In the thread's condition expression, usage of constants is allowed as well as the following

operators: ==, !=, &&, ||, !.

There are restrictions on both possible conditions and the order in which they may occur.

The following notes give details:

●

In expressions that do not explicitly test hsr, an implicit test of hsr==0 is assumed.

●

The compiler would issue an error message if the condition expression is not valid

given the entry table that was chosen in the ETPU_function pragma. If there is an x in

the column of a condition in the table in all qualified entries, the condition cannot be

tested in that expression. For example the statement – if (lsr && pin) is legal because

after evaluating lsr==1 we have entries 10,11,24-31 qualified and in some of them pin

has a specific value.

●

But, if (lsr && m1 && pin) is not valid since lsr && m1 qualifies 10,11,30,31 and in all of

them pin has an X value and therefore none of them might be selected.

●

The order of the conditions and events should be as follows. There are 3 groups.

Identifiers from a lower group number should appear first. There is no order that should

be enforced within the group:

hsr

lsr, m1,m2

pin, flag0, flag1

An error should be generated when appropriate.

The order of the if then else blocks counts:

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