Limitations

AN3349

10/13

Doc ID 018511 Rev 2

5

Limitations

This section lists possible limitations to the eTPU assembly converter.

5.1

Complex expressions

The converter does not analyze complex expressions (for example alu c=3+6-1+2), and

instead copies them as is (in the above example the converted text is: movei c,3+6-1+2).

This approach should deal correctly with most expressions, but some complex expressions

may cause issues when converted.

5.2

Negative numbers

The Byte Craft approach to negative numbers isn't consistent: They are treated as 8 bit

variables or 24 bit variables in some cases, ignored in other cases and not allowed all

together in others. Therefore, the conversion of these numbers is also not completely

consistent.

5.3

Macros

Macros in inline assembly are supported but the -pp switch must be used in order to

convert them correctly. See the command line section for more information.

5.4

Byte Craft errors

In certain specific cases the Byte Craft compiler doesn't create code in consistent fashion

and according to its own documentation. In these cases the converter "fixes" Byte Craft's

errors. This solution ensures that the converted eTPU compiler assembly instruction will

match Byte Craft's original instruction, however in contrast to most cases the generated

binary code of the original instruction and converted instruction will be different (because

Byte Craft's instruction doesn't generate the expected code).

For example:

The instruction "alu c =>> b+a+1." generates the binary code 0x3D330F95 when

assembled in the Byte Craft compiler, even though the meaning of this code is to shift

b+a+1

left instead of right (this seems like a Byte Craft error). The converter will convert the

instruction to "add.shr.one c,b,a". As a result the eTPU compiler and Byte Crafts's

instructions match (their syntax has the same meaning) but the code each instruction will

generate is different (since the converted instruction shifts b+a+1 right, and Byte Craft's

original instruction shifts them left).

5.5

Unsupported features

All Byte Craft directives besides %hex are not supported. Local Byte Craft labels are not

supported as well.