DryOS task and context structures

[hudson]

Are there any CHDK headers that have the layout of the task and context structures used by DryOS?  The chdk code that I see that overloads the dispatch hook just uses hard-coded offsets based on the pointer passed in.

Based on my work in reversing the 5D Mark 2 firmware, they look like this:

Code: C

1. struct context
2. {
3.         uint32_t                cpsr;
4.         uint32_t                r[13];
5.         uint32_t                lr;
6.         uint32_t                pc;
7. };

Code: C

1. struct task
2. {
3.         uint32_t                off_0x00;       // always 0?
4.         uint32_t                off_0x04;       // stack maybe?
5.         uint32_t                off_0x08;       // flags?
6.         void *                  entry;          // off 0x0c
7.         uint32_t                off_0x10;
8.         uint32_t                off_0x14;
9.         uint32_t                off_0x18;
10.         uint32_t                off_0x1c;
11.         uint32_t                off_0x20;
12.         char *                  name;           // off_0x24;
13.         uint32_t                off_0x28;
14.         uint32_t                off_0x2c;
15.         uint32_t                off_0x30;
16.         uint32_t                off_0x34;
17.         uint32_t                off_0x38;
18.         uint32_t                off_0x3c;
19.         uint32_t                off_0x40;
20.         uint32_t                off_0x44;
21.         uint32_t                off_0x48;
22.         struct context *        context;        // off 0x4C
23.         uint32_t                pad_1[12];
24. };
25.  

My dispatch hook looks like this:

Code: C

1. void
2. task_dispatch_hook(
3.         struct context **       context
4. )
5. {
6.         if( !context )
7.                 return;
8.  
9.         // Determine the task address
10.         struct task * task =
11.                 ((uint32_t)context) - offsetof(struct task, context);
12.  
13.         // Do nothing unless a new task is starting via the trampoile
14.         if( task->context->pc != (uint32_t) task_trampoline )
15.                 return;
16.  
17.         // Try to replace the sound device task
18.         // The trampoline will run our entry point instead
19.         if( task->entry == (uint32_t) sound_dev_task )
20.                 task->entry = (uint32_t) my_sound_dev_task;
21. }
22.  

[lorenzo353]

hello,

on page 55 of this Canon document
http://www.canon.com/technology/pageview/pageview.html?page_num=
it is said that Dryos is based on/compliant with micro itron 4.0 RTOS

which specifications are here
http://www.ertl.jp/ITRON/SPEC/mitron4-e.html

and a compatible implementation (TOPPER/JSP) is here
http://www.toppers.jp/download.cgi/jsp-1.4.3.tar.gz

with source code and documentation

Lorenzo

[Chucker]

I am the newest of the newbies. I have just followed the step-by-step progress from Beta to now in creating CHDK for the Canon SD880. Wow! and Thanks! to all who made this possible.
A month ago I loaded the appropriate CHDK for my Canon SD850. Should I expect similar happy results?