What scripting will not do

The scripting support is intended for developers of OpenOCD. It is not the intention that normal OpenOCD users will use tcl scripting extensively, write lots of clever scripts, or contribute back to OpenOCD.

Target scripts can contain new procedures that end users may tinker to their needs without really understanding tcl.

Since end users are not expected to mess with the scripting language, the choice of language is not terribly important to those same end users.

Jim Tcl was chosen as it was easy to integrate, works great in an embedded environment and Øyvind Harboe had experience with it.

Uses of scripting

Default implementation of procedures in tcl/procedures.tcl.

Polymorphic commands for target scripts.
- there will be added some commands in Tcl that the target scripts can replace.
- produce <productionfile> <serialnumber>. Default implementation is to ignore serial number and write a raw binary file to beginning of first flash. Target script can dictate file format and structure of serialnumber. Tcl allows an argument to consist of e.g. a list so the structure of the serial number is not limited to a single string.
- reset handling. Precise control of how srst, trst & tms is handled.
replace some parts of the current command line handler. This is only to simplify the implementation of OpenOCD and will have no externally visible consequences. Tcl has an advantage in that it's syntax is backwards compatible with the current OpenOCD syntax.
external scripting. Low level tcl functions will be defined that return machine readable output. These low level tcl functions constitute the tcl api. flash_banks is such a low level tcl proc. "flash banks" is an example of a command that has human readable output. The human readable output is expected to change in between versions of OpenOCD. The output from flash_banks may not be in the preferred form for the client. The client then has two choices a) parse the output from flash_banks or b) write a small piece of tcl to output the flash_banks output to a more suitable form. The latter may be simpler.

External scripting

The embedded Jim Tcl interpreter in OpenOCD is very limited compared to any full scale PC hosted scripting language.

The goal is to keep the internal Jim Tcl interpreter as small as possible and allow any advanced scripting, especially scripting that interacts with the host, run on the host and talk to OpenOCD via the TCP/IP scripting connection.

Another problem with Jim Tcl is that there is no debugger for it.

With a bit of trickery it should be possible to run Jim Tcl scripts under a Tcl interpreter on a PC. The advantage would be that the Jim Tcl scripts could be debugged using a standard PC Tcl debugger.

The rough idea is to write an unknown proc that sends unknown commands to OpenOCD.

Basically a PC version of startup.tcl. Patches most gratefully accepted! :-)