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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