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Why
ST is a very robust and easy to understand language. A good fit for industrial applications. But on the internet you find by far more example algorithms, applications and libraries written in C or other languages. The mission of this project is to make the step from a working C example code to a working ST code as small as possible.
Technique
The transpiler is built using the very old but famous and solid compiler builder tools flex and yacc / bison. So the code transformation consists only of two steps:
- flex: tokenize the ANSI C code
- bison: parse and transform the tokens to ST code
As the transformations from the tokens to the resulting ST code is done in just one step, we have to live with a few limitations, which can't be transformed as the ST language doesn't support those language constructs.
Features
The following features are currently tested, and should work therefore:
| feature | C | ST |
|---|---|---|
| expressions | a = b * (c + d) * e; | a := b * ( c + d ) * e; |
| lvalues | c++; | ((c:=c+1)-1); |
| case | switch (value) | CASE value OF |
| for | for (i=0; i < 5; i++) | WHILE i < 5; |
| while | while (x < 10) | WHILE x < 10 DO |
| named structs / unions | struct test | TYPE test: STRUCT |
| unnamed structs / unions | union ...; | flattened as members into the type in which they are embedded |
| typedef | typedef struct ... t_struct; | TYPE t_struct: Id2036658550; |
| arrays | char arr2[1][2]; | arr2: ARRAY[0..(1-1),0..(2-1)] OF BYTE; |
Limitations
The following features will definitely not be supported by this transpiler, because of its design.
- Explicit type conversions of user defined data types (e.g. structs)
- Function pointers
- Pointer arithmetics
- Static variables or functions
Usage
This project is in a proof-of-concept phase. So it can't be easily used, yet, nor would I try to encourage non-experienced people to use it in this state.
If your code is proberly pre processed, you can quickly try it with the web-version of the transpiler.