src/scripting.txt

   1 Plan for hosted scripting support in OpenOCD
   2 ============================================
   3
   4 What scripting will not do
   5 ==========================
   6 It is not the intention that normal OpenOCD users will
   7 use tcl scripting extensively, write lots of clever scripts,
   8 or contribute back to OpenOCD.
   9
  10 The scripting support is intended for developers of OpenOCD.
  11
  12 Target scripts can contain new procedures that end users may
  13 tinker to their needs without really understanding tcl.
  14
  15 Since end users are not expected to mess with the scripting
  16 language, the choice of language is not terribly important
  17 to those same end users.
  18
  19 Jim Tcl was chosen as it was easy to integrate, works
  20 great in an embedded environment and Øyvind Harboe
  21 had experience with it.
  22
  23 Uses of scripting
  24 =================
  25 Default implementation of procedures in tcl/procedures.tcl.
  26
  27 - Polymorphic commands for target scripts.
  28   - there will be added some commands in Tcl that the target
  29     scripts can replace.
  30   - produce <productionfile> <serialnumber>. Default implementation
  31     is to ignore serial number and write a raw binary file
  32     to beginning of first flash. Target script can dictate
  33     file format and structure of serialnumber. Tcl allows
  34     an argument to consist of e.g. a list so the structure of
  35     the serial number is not limited to a single string.
  36   - reset handling. Precise control of how srst, trst &
  37     tms is handled.
  38 - replace some parts of the current command line handler.
  39   This is only to simplify the implementation of OpenOCD
  40   and will have no externally visible consequences.
  41   Tcl has an advantage in that it's syntax is backwards
  42   compatible with the current OpenOCD syntax.
  43 - external scripting. Low level tcl functions will be defined
  44   that return machine readable output. These low level tcl
  45   functions constitute the tcl api. flash_banks is such
  46   a low level tcl proc. "flash banks" is an example of
  47   a command that has human readable output. The human
  48   readable output is expected to change inbetween versions
  49   of OpenOCD. The output from flash_banks may not be
  50   in the preferred form for the client. The client then
  51   has two choices a) parse the output from flash_banks
  52   or b) write a small piece of tcl to output the
  53   flash_banks output to a more suitable form. The latter may
  54   be simpler.
  55
  56
  57 External scripting
  58 ==================
  59 The embedded Jim Tcl interpreter in OpenOCD is very limited
  60 compared to any full scale PC hosted scripting language.
  61
  62 The goal is to keep the internal Jim Tcl interpreter as
  63 small as possible and allow any advanced scripting,
  64 especially scripting that interacts with the host,
  65 run on the host and talk to OpenOCD via the TCP/IP
  66 scripting connection.
  67
  68 Another problem with Jim Tcl is that there is no debugger
  69 for it.
  70
  71 With a bit of trickery it should be possible to run Jim
  72 Tcl scripts under a Tcl interpreter on a PC. The advantage
  73 would be that the Jim Tcl scripts could be debugged using
  74 a standard PC Tcl debugger.
  75
  76 The rough idea is to write an unknown proc that sends
  77 unknown commands to OpenOCD.
  78
  79 Basically a PC version of startup.tcl. Patches most
  80 gratefully accepted! :-)