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135 lines
4.8 KiB
Markdown
135 lines
4.8 KiB
Markdown
A JIT input file is a C++ input file that can be used along side a python input file, or even replace the python input file. The JIT input file includes "S_source.hh" that gives it access to the entire simulation. The code in a JIT input file is compiled into a shared library during simulation initialization. The simulation dynamically opens the shared library and runs a specific function called "run_me" that must be defined in the JIT input file. There are a couple of advantages to this type of input file.
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1. Once compiled, a JIT input file is orders of magnitude faster to execute than a python equivalent. That is because there is no python is involved, everything is C++.
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2. Full C++ functionality. Our SWIG/python code cannot access everything in the sim, C++ can.
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3. Events and malfunctions written in C++ and inputted through a JIT input file will not impact real-time operations as much as python events.
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4. A JIT input file can be loaded and executed from a python input file. you don’t have to choose one type or the other.
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An example JIT input file from SIM_Ball++_L1/RUN_cpp_input/input.cpp
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```c++
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/*
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To use this as an input file include this file on the command line.
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S_main_${TRICK_HOST_CPU}.exe RUN_<dir>/input.cpp
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Trick will compile and link this file at simulation runtime. The
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run_me function will automatically be executed during the
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input_processor phase of initialization.
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*/
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// need access to private/protected things? uncomment these.
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//#define private public
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//#define protected public
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#include "../S_source.hh"
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#include "trick/CheckPointRestart_c_intf.hh"
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#include "trick/realtimesync_proto.h"
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#include "trick/external_application_c_intf.h"
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extern "C" int run_event_1() {
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message_publish(1, "event 1 fired!\n") ;
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return 0 ;
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}
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extern "C" int run_event_2() {
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message_publish(1, "event 2 fired!\n") ;
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return 0 ;
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}
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extern "C" int run_event_3() {
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message_publish(1, "event 3 fired!\n") ;
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return 0 ;
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}
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extern "C" int run_event_4() {
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message_publish(1, "event 4 fired!\n") ;
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return 0 ;
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}
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extern "C" int run_event_before() {
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message_publish(1, "event before fired!\n") ;
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return 0 ;
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}
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extern "C" int run_event_before2() {
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message_publish(1, "event before2 fired!\n") ;
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return 0 ;
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}
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extern "C" int run_event_after() {
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message_publish(1, "event after fired!\n") ;
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return 0 ;
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}
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extern "C" int remove_events() {
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event_manager_remove_event(event_manager_get_event("event_3")) ;
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event_manager_remove_event(event_manager_get_event("event_before")) ;
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event_manager_remove_event(event_manager_get_event("event_after")) ;
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return 0 ;
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}
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/*
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Trick will look for the run_me function and execute it during simulation initialization.
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*/
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extern "C" int run_me() {
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// modify variables within sim_objects.
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ball.obj.state.input.position[0] = 6.0 ;
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ball.obj.state.input.position[1] = 6.0 ;
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checkpoint_pre_init(true) ;
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// add read events
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jit_add_read( 90.0 , "run_event_1" ) ;
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jit_add_read( 80.0 , "run_event_2" ) ;
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// add cyclic event
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jit_add_event( "run_event_3" , "event_3" , 100.0 ) ;
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// events tied to jobs
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jit_add_event_before( "run_event_before", "event_before", "ball.obj.state_print" ) ;
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jit_add_event_after( "run_event_after", "event_after", "ball.obj.state_print" ) ;
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// add a read event that removes all other events.
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jit_add_read( 150.0 , "remove_events" ) ;
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// tries to add event that does not exist. (currently silents fails)
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jit_add_read( 190.0 , "dne_event" ) ;
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exec_set_terminate_time(200.0) ;
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/*
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real_time_enable() ;
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trick_real_time.itimer.enable() ;
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sim_control_panel_set_enabled(true) ;
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*/
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return 0 ;
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}
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```
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A JIT input file may be used with a python input file or in place of a python input file. To use a JIT input file from within a python script use the following calls
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```python
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# jit_compile_and_run specifies the c++ input file, and an optional function name to run. The function
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# must fit the c++ prototype 'extern "C" int function()'. If no function name is given, the function
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# "run_me" is searched for and ran.
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trick.jit_compile_and_run("RUN_cpp_input/input.cpp")
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trick.jit_compile_and_run("RUN_cpp_input/input.cpp", "run_event_1")
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# a c++ library can be compiled and c++ code executed separately.
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trick.jit_compile("RUN_cpp_input/input.cpp")
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trick.jit_run("RUN_cpp_input/jitlib/libinput.so", "run_event_1")
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# executing a c++ function from input.cpp at a later time. Note: The add_read call will still be
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# processed in python causing a real time hit.
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trick.add_read(150, """trick.jit_run("RUN_cpp_input/jitlib/libinput.so", "run_event_1")""")
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```
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To use a JIT input file in place of the normal python input file, use the C++ input file on the command line.
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```
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./S_main_<TRICK_HOST_CPU>.exe RUN_cpp_input/input.cpp
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```
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[Continue to Event Manager](Event-Manager)
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