INtime SDK Help
iwin32 Design
The two APIs each implement a separate set of object types. Although it should be perfectly feasible to code a thread exclusively with one of the two APIs, there may be different threads in the system at the same time, that use different APIs. What happens if such threads need to communicate?
We have to define the terms "pure INtime thread" and "iwin32 thread": a pure INtime thread is a thread created by the INtime function CreateRtThread; an iwin32 thread is either the main thread of a process linked with the iwin32.lib library or a thread created by one of the iwin32 functions: CreateThread, RtCreateThread, RtCreateTimer, RtAttachInterruptVector, RtAttachInterruptVectorEx, RtAttachShutdownHandler.
For the communication between processes in the Windows environment and iwin32 processes in INtime, a set of functions is available named 'iwin32x'. These functions can only be used from C or C++ programs. The API provides a subset of the iwin32 API (for obvious reasons, a number of iwin32 functions is not available here) and also includes specific functions, for example to find an INtime node.
The iwin32x functions include:
| Event handling | RtCreateEvent RtOpenEvent RtPulseEvent RtResetEvent RtSetEvent |
| Mutexes | RtCreateMutex RtOpenMutex RtReleaseMutex |
| Process handling | RtCreateProcess RtGetExitCodeProcess RtOpenProcess RtTerminateProcess |
| Semaphores | RtCreateSemaphore RtOpenSemaphore RtReleaseSemaphore |
| Shared memory | RtCreateSharedMemory RtOpenSharedMemory |
| General purpose | RtCloseHandle RtImportHandle RtSetNode RtWaitForSingleObject |
INtime supports three thread priority ranges. Internally the INtime range is always used: from 0 to 254, zero being the most important. Priorities between 0 and 127 influence interrupt enabling.
All Windows interrupts are masked when an INtime thread of any priority is running.
INtime thread priority 0-2 masks all RT interrupts including the INtime system tick.
INtime thread priority 3-60 masks all RT interrupts with IDT vectors 224-239.
INtime thread priority 61-255 makss no RT interrupts.
Multiple MSI uses AllocateRtInterrupts() to allocate vectors in the range 96-223. Interrupts on these vectors are masked by threads with priority 0-128.
Iwin32 (functions such as GetThreadPriority, SetThreadPriority) has a priority range from -15 to +15, the numerically highest value is the best. These values are mapped to the INtime priorities as follows:
Note: These priorities are used when the function exists in Win32 and does not have an Rt prefix.
Note: THREAD_PRIORITY_TIME_CRITICAL, which corresponds to priority 0 in INtime, also blocks the scheduler and interrupts. Care should be taken when using this priority. INtime priorities 0-2 will block the INtime clock.
| Iwin32 priority | INtime priority | Win32 priority name |
|---|---|---|
| -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
254 246 238 230 222 214 206 198 190 182 174 166 158 150 142 134 126 117 108 99 90 81 72 63 54 45 36 27 18 9 0 |
THREAD_PRIORITY_IDLE THREAD_PRIORITY_LOWEST THREAD_PRIORITY_BELOW_NORMAL THREAD_PRIORITY_NORMAL THREAD_PRIORITY_ABOVE_NORMAL THREAD_PRIORITY_HIGHEST THREAD_PRIORITY_TIME_CRITICAL |
iwin32 does not support priority classes.
RTX-compatible thread priorities (RtSetThreadPriority, RtAtttachInterruptVector etc) range from 0 to 127, with 127 being the best priority.
An RTX-compatible priority is translated into an INtime priority as follows:
prio(INtime) = 254 - 2*prio(RTX)
Note that the lowest Win prio now translates in INtime prio 254, which means time sharing with Windows in shared mode.