Atmel CAVR-4 Manuale Utente

CAVR-4

Checking module consistency

Reference Guide

For an example of using the runtime model attribute 

_ _rt_version

 for checking 

module consistency on used calling convention, see Hints for using the new calling 
convention, page 100.

The following assembler source code provides a function, 

part2

, that counts the 

number of times it has been called by increasing the register 

R4

. The routine assumes 

that the application does not use 

R4

 for anything else, that is, the register has been locked 

for usage. To ensure this, a runtime module attribute, 

_ _reg_r4

, has been defined with 

a value 

counter

. This definition will ensure that this specific module can only be linked 

with either other modules containing the same definition, or with modules that do not 
set this attribute. Note that the compiler sets this attribute to 

free

, unless the register is 

locked.

RTMODEL

"RTMODEL "__reg_r4", "counter"

MODULE

myCounter

PUBLIC

myCounter

RSEG

CODE:CODE:NOROOT(1)

myCounter:

INC

R4

RET

ENDMOD

END

If this module is used in an application that contains modules where the register 

R4

 has 

not been locked, an error is issued by the linker:

Error[e117]: Incompatible runtime models. Module myCounter 

specifies that '_ _reg_r4' must be 'counter', but module part1 

has the value 'free'

In cases where the predefined runtime model attributes are not sufficient, you can define 
your own attributes by using the 

RTMODEL

 assembler directive. For each property, select 

a key and a set of values that describe the states of the property that are incompatible. 
Note that key names that start with two underscores are reserved by IAR Systems.

For example, if you have a UART that can run in two modes, you can specify a runtime 
model attribute, for example 

uart

. For each mode, specify a value, for example 

mode1

 

and 

mode2

. You should declare this in each module that assumes that the UART is in a 

particular mode. This is how it could look like in one of the modules:

#pragma rtmodel="UART", "mode1"