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[/] [forwardcom/] [examples/] [event.as] - Rev 147
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/**************************** events.as *************************************
* Author: Agner Fog
* date created: 2018-03-23
* Last modified: 2018-03-23
* Version: 1.00
* Project: ForwardCom example
* Description: Test event handler system
*
* Copyright 2018 GNU General Public License http://www.gnu.org/licenses
******************************************************************************/
// define event IDs
%EVT_CONSTRUCT = 1 // call static constructors and initialization procedures before calling main
%EVT_DESTRUCT = 2 // call static destructors and clean up after return from main
%EVT_MY_DEF = 0x100 // arbitrary user-defined event id
%KEY = 1 // arbitrary key for my event
%DEFAULT_PRIORITY = 0x1000 // default event priority
/*
Event records must be stored in a special read-only section with attribute 'event_hand'.
These records will be reordered and combined by the linker.
Each record contains:
1. A scaled relative pointer to the event handler function
2. Event priority
3. Key
4. Event ID
*/
events section read event_hand
int32 (constructor-__ip_base)/4, DEFAULT_PRIORITY, 0, EVT_CONSTRUCT
int32 (destructor-__ip_base)/4, DEFAULT_PRIORITY, 0, EVT_DESTRUCT
int32 (event1-__ip_base)/4, DEFAULT_PRIORITY, KEY, EVT_MY_DEF
int32 (event2-__ip_base)/4, DEFAULT_PRIORITY+1, KEY, EVT_MY_DEF
events end
const section read ip // read-only data section
// char strings with terminating zero
hello: int8 "\nMain called", 0
constr: int8 "\nTesting event handler system:\n\n\nConstructor called", 0
destr: int8 "\nDestructor called\n\n", 0
texte1: int8 "\nEvent handler 1 called", 0
texte2: int8 "\nEvent handler 2 called (higher priority)", 0
const end
code section execute align = 4 // code section
extern __ip_base: ip // reference point
extern _puts: function // library function: write string to stdout
extern _raise_event: function // library function: make an event
_main function public // main is the program entry called by the startup code
int64 r0 = address([hello]) // calculate address of string
call _puts // call puts: write string pointed to by r0
// now create an event with key 1 and event ID = EVT_MY_DEF
int64 r0 = KEY + (EVT_MY_DEF << 32) // constant expression calculated by assembler
call _raise_event // make the event
int64 r0 = 0 // program return value
return
_main end
// this function is assigned to the EVT_CONSTRUCT event to be called before main
constructor function
int64 r0 = address([constr]) // calculate address of string
call _puts // call puts. parameter is in r0
int64 r0 = 1 // return 1 to allow further event handlers
return
constructor end
// this function is assigned to the EVT_DESTRUCT event to be called after main
destructor function
int64 r0 = address([destr]) // calculate address of string
call _puts // call puts. parameter is in r0
int64 r0 = 1 // return 1 to allow further event handlers
return
destructor end
// this function is assigned to the user-defined EVT_MY_DEF event to be called at this custum event
event1 function
int64 r0 = address([texte1]) // calculate address of string
call _puts // call puts. parameter is in r0
int64 r0 = 1 // return 1 to allow further event handlers
return
event1 end
// this function is also assigned to the user-defined EVT_MY_DEF, but with a higher priority. It will be called first
event2 function
int64 r0 = address([texte2]) // calculate address of string
call _puts // call puts. parameter is in r0
int64 r0 = 1 // return 1 to allow further event handlers
return
event2 end
code end
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