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572 | with Ada.Calendar;
with Ada.Numerics.Float_Random;
package body HAC_Sys.PCode.Interpreter.Tasking is
function Any_Task_Delayed (CD : Compiler_Data; ND : Interpreter_Data) return Boolean is
task_delayed : Boolean := False;
begin
for t in TRange'First .. CD.Tasks_Definitions_Count loop
task_delayed := ND.TCB (t).TS = Delayed or
ND.TCB (t).TS = TimedRendz or
ND.TCB (t).TS = TimedWait;
exit when task_delayed;
end loop;
return task_delayed;
end Any_Task_Delayed;
function EIndex (CD : Compiler_Data; Entry_Index : Integer) return Integer is
i, e : Integer;
begin
e := -1;
i := 1;
while i <= CD.Entries_Count and e = -1 loop
if Entry_Index = CD.Entries_Table (i) then
e := i;
end if;
i := i + 1;
end loop;
return e;
end EIndex;
function First_Caller (CD : Compiler_Data; ND : in out Interpreter_Data; Entry_Index : Integer) return Integer is
ix, val : Integer;
begin
ix := EIndex (CD, Entry_Index);
if ND.EList (ix).First = null then
val := -1;
else
val := ND.EList (ix).First.Task_Index;
end if;
return val;
end First_Caller;
procedure Queue (
CD : Compiler_Data;
ND : in out Interpreter_Data;
Entry_Index : Integer;
Calling_Task : TRange
)
is
ix : constant Integer := EIndex (CD, Entry_Index);
enode_var : constant Eptr := new Enode'(Task_Index => Calling_Task, Next => null);
E_Q_Header : EHeader renames ND.EList (ix);
begin
-- Queue an entry call by Calling_Task for entry 'Entry'.
if E_Q_Header.First = null then
E_Q_Header.First := enode_var;
else
E_Q_Header.Last.Next := enode_var;
end if;
E_Q_Header.Last := enode_var;
end Queue;
procedure Do_Tasking_Operation (CD : Compiler_Data; ND : in out Interpreter_Data) is
Curr_TCB : Task_Control_Block renames ND.TCB (ND.CurTask);
IR : Order renames ND.IR;
procedure Do_Accept_Rendezvous is
-- Hathorn, Cramer
H1, H2, H3 : Integer;
begin
H1 := Integer (IR.Y); -- entry pointer
H2 := First_Caller (CD, ND, H1); -- first waiting task
H3 := Integer (CD.IdTab (H1).lev); -- level of accepting entry
if H2 >= 0 then
-- start rendzv if call is waiting
Curr_TCB.DISPLAY (Defs.Nesting_Level (H3 + 1)) := ND.TCB (H2).B; -- address callers
-- parms
Curr_TCB.InRendzv := H2; -- indicate that task is in Rendzv
if ND.TCB (H2).TS = TimedRendz then
ND.TCB (H2).TS := WaitRendzv;
end if;
else
-- or put self to sleep
Curr_TCB.SUSPEND := H1;
Curr_TCB.TS := WaitRendzv; -- status is waiting for
-- rendezvous
Curr_TCB.PC := Curr_TCB.PC - 1; -- do this
-- step again when awakened
end if;
ND.SWITCH := True;
end Do_Accept_Rendezvous;
procedure Do_End_Rendezvous is
-- Hathorn
function Remove_First (Entry_Index : Integer) return TRange is
ix, val : Integer;
dmy : Eptr;
begin
ix := EIndex (CD, Entry_Index);
declare
E_Q_Header : EHeader renames ND.EList (ix);
begin
val := E_Q_Header.First.Task_Index;
if E_Q_Header.First = E_Q_Header.Last then
E_Q_Header.First := null;
E_Q_Header.Last := null;
else
dmy := E_Q_Header.First;
E_Q_Header.First := E_Q_Header.First.Next;
Dispose (dmy);
end if;
end;
return val;
end Remove_First;
--
H1, H2 : Integer;
begin
Curr_TCB.InRendzv := NilTask; -- indicate rendezvous has ended
H1 := Integer (ND.IR.Y); -- entry pointer
H2 := Remove_First (H1); -- waiting task pointer
if H2 >= 0 then
-- wake up waiting task
ND.TCB (H2).SUSPEND := 0;
ND.TCB (H2).TS := Ready;
ND.SWITCH := True;
end if;
end Do_End_Rendezvous;
procedure Do_Selective_Wait is
use type Defs.HAC_Float, Defs.Nesting_Level, Ada.Calendar.Time;
H1, H2, H3 : Integer;
begin
case IR.X is
when 1 => -- Start Selective Wait seq.
Curr_TCB.R1.I := 0; -- next instruction if delay expires
Curr_TCB.R2 := GR_Real (-1.0); -- delay time
when 2 => -- Retain entry ID
Curr_TCB.R3.I := IR.Y;
when 3 => -- Accept if its still on queue
H1 := Integer (Curr_TCB.R3.I);
H2 := First_Caller (CD, ND, H1); -- first waiting task
H3 := Integer (CD.IdTab (H1).lev); -- level of accepting entry
if H2 >= 0 then
Curr_TCB.DISPLAY (Defs.Nesting_Level (H3 + 1)) := ND.TCB (H2).B;
-- address callers parms
Curr_TCB.InRendzv := H2; -- indicate task InRendz
if ND.TCB (H2).TS = TimedRendz then -- turn off entry timeout
ND.TCB (H2).TS := WaitRendzv; -- if it was on
end if;
else
Curr_TCB.PC := Defs.Index (IR.Y); -- Jump to patched in address
end if;
ND.SWITCH := True;
when 4 => -- Update minimum delay time
if ND.S (Curr_TCB.T).R > 0.0 then
if Curr_TCB.R2.R = -1.0 then
Curr_TCB.R2.R := ND.S (Curr_TCB.T).R;
Curr_TCB.R1.I := IR.Y; -- ins after JMP
else
if ND.S (Curr_TCB.T).R < Curr_TCB.R2.R then
Curr_TCB.R2.R := ND.S (Curr_TCB.T).R;
Curr_TCB.R1.I := IR.Y; -- ins after JMP
end if;
end if;
end if;
Pop (ND);
when 5 | 6 => -- end of SELECT
if Curr_TCB.R2.R > 0.0 then
-- Timed Wait
Curr_TCB.TS := TimedWait;
ND.SYSCLOCK := Ada.Calendar.Clock;
Curr_TCB.WAKETIME := ND.SYSCLOCK + Duration (Curr_TCB.R2.R);
Curr_TCB.PC := Defs.Index (IR.Y); -- Do SELECT again when awakened by caller
ND.SWITCH := True; -- give up control
end if;
-- AVL -- TERMINATE
-- IS THE PARENT TASK COMPLETED?
if ND.TCB (0).TS = Completed and then ND.CurTask /= 0 and then IR.X /= 6 then
ND.Nb_Callers := 0; -- LET'S SEE IF THERE ARE CALLERS
for ITERM in 1 .. CD.Entries_Count loop
if ND.EList (ITERM).First /= null then
ND.Nb_Callers := ND.Nb_Callers + 1;
end if;
end loop;
-- YES, NO CALLERS
if ND.Nb_Callers = 0 then -- YES, NO CALLERS
-- ARE THE SIBLING TASKS EITHER COMPLETED OR
-- IN THE SAME STATE AS CURTASK?
ND.Nb_Complete := 0;
for ITERM in 1 .. CD.Tasks_Definitions_Count loop
if ND.TCB (ITERM).TS = Completed then
ND.Nb_Complete := ND.Nb_Complete + 1;
else
if ND.TCB (ITERM).TS = Curr_TCB.TS then
ND.Nb_Complete := ND.Nb_Complete + 1;
else
if ND.TCB (ITERM).TS = Ready and then
Curr_TCB.TS = Running
then
ND.Nb_Complete := ND.Nb_Complete + 1;
end if;
end if;
end if;
end loop;
if CD.Tasks_Definitions_Count = ND.Nb_Complete then
-- YES, THEN ALL TASKS ARE NOW TERMINATING
for ITERM in 1 .. CD.Tasks_Definitions_Count loop
ND.TCB (ITERM).TS := Terminated;
end loop;
ND.PS := FIN;
end if;
end if;
end if;
-- if ir.x = 6 then
-- begin
-- term := false ; {Task doesn't have a terminate}
-- end ; {alternative}
--
when others =>
null; -- [P2Ada]: no otherwise / else in Pascal
end case;
end Do_Selective_Wait;
procedure Do_Signal_Semaphore is
H1 : constant Integer := Integer (ND.S (Curr_TCB.T).I);
H2, H3 : Integer;
use Ada.Numerics.Float_Random;
use type Defs.HAC_Integer;
begin
Pop (ND);
H2 := CD.Tasks_Definitions_Count + 1;
H3 := Integer (Random (ND.Gen) * Float (H2));
while H2 >= 0 and then ND.TCB (H3).TS /= WaitSem and then ND.TCB (H3).SUSPEND /= H1
loop
H3 := (H3 + 1) mod (Defs.TaskMax + 1);
H2 := H2 - 1;
end loop;
if H2 < 0 or else ND.S (H1).I < 0 then
ND.S (H1).I := ND.S (H1).I + 1;
else
ND.TCB (H3).SUSPEND := 0;
ND.TCB (H3).TS := Ready;
end if;
Curr_TCB.TS := Ready; -- end critical section
ND.SWITCH := True;
end Do_Signal_Semaphore;
procedure Do_Wait_Semaphore is
H1 : constant Integer := Integer (ND.S (Curr_TCB.T).I);
use type Defs.HAC_Integer;
begin
Pop (ND);
if ND.S (H1).I > 0 then
ND.S (H1).I := ND.S (H1).I - 1;
Curr_TCB.TS := Critical; -- In a critical section, task gets
-- exclusive access to the virtual
else
-- processor until section ends.
Curr_TCB.SUSPEND := H1;
Curr_TCB.TS := WaitSem;
ND.SWITCH := True;
end if;
end Do_Wait_Semaphore;
procedure Do_Set_Quantum_Task is
use type Defs.HAC_Float;
begin
-- Cramer
if ND.S (Curr_TCB.T).R <= 0.0 then
ND.S (Curr_TCB.T).R := Defs.HAC_Float (TSlice);
end if;
Curr_TCB.QUANTUM := Duration (ND.S (Curr_TCB.T).R);
Pop (ND);
end Do_Set_Quantum_Task;
procedure Do_Set_Task_Priority is
use type Defs.HAC_Integer;
begin
-- Cramer
if ND.S (Curr_TCB.T).I > Defs.PriMax then
ND.S (Curr_TCB.T).I := Defs.PriMax;
end if;
if ND.S (Curr_TCB.T).I < 0 then
ND.S (Curr_TCB.T).I := 0;
end if;
Curr_TCB.Pcontrol.UPRI := Integer (ND.S (Curr_TCB.T).I);
Pop (ND);
end Do_Set_Task_Priority;
procedure Do_Set_Task_Priority_Inheritance is
use type Defs.HAC_Integer;
begin
-- Cramer
Curr_TCB.Pcontrol.INHERIT := ND.S (Curr_TCB.T).I /= 0;
-- Set priority inherit indicator
Pop (ND);
end Do_Set_Task_Priority_Inheritance;
procedure Do_Delay is
use type Ada.Calendar.Time;
begin
if ND.S (Curr_TCB.T).Dur > 0.0 then
if ND.Scheduler = Single_Task then
ND.Single_Task_Delay_Pending := True;
end if;
Curr_TCB.TS := Delayed; -- set task state to delayed
ND.SYSCLOCK := Ada.Calendar.Clock; -- update System Clock
Curr_TCB.WAKETIME := ND.SYSCLOCK + ND.S (Curr_TCB.T).Dur; -- set wakeup time
ND.SWITCH := True; -- give up control
end if;
Pop (ND);
end Do_Delay;
procedure Do_Halt_Interpreter is
begin
if ND.TActive = 0 then
ND.PS := FIN;
-- OK even when PS = Exception_Raised.
-- At this point the exception is clearly unhandled.
else
ND.TCB (0).TS := Completed;
ND.SWITCH := True;
Curr_TCB.PC := Curr_TCB.PC - 1;
end if;
end Do_Halt_Interpreter;
begin
case Tasking_Opcode (ND.IR.F) is
when k_Accept_Rendezvous => Do_Accept_Rendezvous;
when k_End_Rendezvous => Do_End_Rendezvous;
when k_Wait_Semaphore => Do_Wait_Semaphore;
when k_Signal_Semaphore => Do_Signal_Semaphore;
when k_Set_Quantum_Task => Do_Set_Quantum_Task;
when k_Set_Task_Priority => Do_Set_Task_Priority;
when k_Set_Task_Priority_Inheritance => Do_Set_Task_Priority_Inheritance;
when k_Selective_Wait => Do_Selective_Wait;
when k_Delay => Do_Delay;
when k_Halt_Interpreter => Do_Halt_Interpreter;
end case;
end Do_Tasking_Operation;
procedure Init_main_task (CD : Compiler_Data; ND : in out Interpreter_Data) is
use Ada.Numerics.Float_Random;
use type Defs.HAC_Integer;
begin
Reset (ND.Gen); -- initialize pseudo-random number generator
-- After compiled, just begin exec
-- Initialize run-time stack
ND.S (1).I := 0;
ND.S (2).I := 0;
ND.S (3).I := -1;
ND.S (4).I := Defs.HAC_Integer (CD.Main_Proc_Id_Index);
declare
Main_TCB : Task_Control_Block renames ND.TCB (0);
begin
Main_TCB.PC := Defs.Index (CD.IdTab (CD.Main_Proc_Id_Index).adr_or_sz); -- first pcode instruction
Main_TCB.T := CD.Blocks_Table (CD.IdTab (CD.Main_Proc_Id_Index).block_or_pkg_ref).VSize - 1;
Main_TCB.B := 0;
Main_TCB.TS := Ready;
Main_TCB.InRendzv := NilTask;
Main_TCB.DISPLAY (0) := 0; -- Added for modularity (library-level calls), in 2021
Main_TCB.DISPLAY (1) := 0; -- In Pascal-S.
Main_TCB.STACKSIZE := Defs.StMax - (CD.Tasks_Definitions_Count * Defs.STKINCR);
Main_TCB.SUSPEND := 0;
Main_TCB.QUANTUM := TSlice;
Main_TCB.Pcontrol.UPRI := 0;
Main_TCB.Pcontrol.INHERIT := False;
Main_TCB.LASTRUN := ND.Start_Time;
Main_TCB.Exception_Info.Currently_Raised := (No_Exception, 0);
Main_TCB.WAKETIME := ND.Start_Time; -- Added 2020-06-23 for Single_Task
end;
end Init_main_task;
procedure Init_other_tasks (CD : Compiler_Data; ND : in out Interpreter_Data) is
H1 : Integer;
use type Defs.HAC_Integer;
begin
for Task_To_Init in 1 .. CD.Tasks_Definitions_Count loop
declare
Curr_TCB : Task_Control_Block renames ND.TCB (Task_To_Init);
begin
H1 := CD.Tasks_Definitions_Table (Task_To_Init);
Curr_TCB.PC := Defs.Index (CD.IdTab (H1).adr_or_sz);
Curr_TCB.B := ND.TCB (Task_To_Init - 1).STACKSIZE + 1;
Curr_TCB.T := Curr_TCB.B + CD.Blocks_Table (CD.IdTab (H1).block_or_pkg_ref).VSize - 1;
ND.S (Curr_TCB.B + 1).I := 0;
ND.S (Curr_TCB.B + 2).I := 0;
ND.S (Curr_TCB.B + 3).I := -1;
ND.S (Curr_TCB.B + 4).I := Defs.HAC_Integer (H1);
Curr_TCB.DISPLAY (1) := 0;
Curr_TCB.DISPLAY (2) := Curr_TCB.B;
Curr_TCB.STACKSIZE := Curr_TCB.B + Defs.STKINCR - 1;
Curr_TCB.SUSPEND := 0;
Curr_TCB.TS := Ready;
Curr_TCB.InRendzv := NilTask;
Curr_TCB.QUANTUM := TSlice;
Curr_TCB.Pcontrol.UPRI := 0;
Curr_TCB.Pcontrol.INHERIT := False;
Curr_TCB.LASTRUN := ND.Start_Time;
Curr_TCB.Exception_Info.Currently_Raised := (No_Exception, 0);
end;
end loop;
-- Initially no queued entry calls
for E_Idx in 1 .. CD.Entries_Count loop
ND.EList (E_Idx).Task_Index := TRange (CD.IdTab (CD.Entries_Table (E_Idx)).adr_or_sz); -- Task index
ND.EList (E_Idx).First := null;
ND.EList (E_Idx).Last := null;
end loop;
ND.TActive := CD.Tasks_Definitions_Count; -- All tasks are active initially
ND.Scheduler := (if ND.TActive = 0 then Single_Task else 1);
ND.CurTask := 0; -- IT WAS -1 ?
ND.SWITCH := True;
ND.TIMER := ND.Start_Time; -- was 0.0
ND.PS := Running;
end Init_other_tasks;
procedure ShowQ (
CD : Compiler_Data;
ND : in out Interpreter_Data;
Entry_Index : Integer
)
is
ix : constant Integer := EIndex (CD, Entry_Index);
p : Eptr := ND.EList (ix).First;
use Defs, Ada.Text_IO;
begin
Put ("Dumping q for entry " & A2S (CD.IdTab (Entry_Index).name) & " entry index=");
IIO.Put (HAC_Integer (ix));
New_Line;
if p = null then
Put ("*** EMPTY ***");
New_Line;
else
loop
Put ("Task ");
Put (A2S (CD.IdTab (CD.Tasks_Definitions_Table (p.Task_Index)).name));
New_Line;
p := p.Next;
exit when p = null;
end loop;
end if;
end ShowQ;
procedure Wake_Tasks (
CD : Compiler_Data;
ND : in out Interpreter_Data;
Result : out Boolean
)
is
procedure Purge (Entry_Index : Integer; t : TRange) is
p, q : Eptr; -- has timed out, the entry
ix : Integer; -- is purged from the q.
begin
ix := EIndex (CD, Entry_Index);
q := null;
p := ND.EList (ix).First;
while p /= null loop
if p.Task_Index = t then
if ND.EList (ix).First = ND. EList (ix).Last then
ND.EList (ix).First := null;
ND.EList (ix).Last := null;
else
if p = ND.EList (ix).First then
ND.EList (ix).First := p.Next;
else
if p = ND.EList (ix).Last then
ND.EList (ix).Last := q;
q.Next := null;
else
q.Next := p.Next;
end if;
end if;
end if;
Dispose (p);
p := null; -- to exit loop
else
-- try next entry in list
q := p;
p := p.Next;
end if;
end loop;
end Purge;
--
count : Integer := 0;
use type Ada.Calendar.Time;
begin
for t in 0 .. CD.Tasks_Definitions_Count loop
if (ND.TCB (t).TS = Delayed or else
ND.TCB (t).TS = TimedRendz or else
ND.TCB (t).TS = TimedWait)
and then
ND.SYSCLOCK >= ND.TCB (t).WAKETIME
then
if ND.TCB (t).TS = TimedRendz then
ND.TCB (t).R1.I := 0; -- timeout on rendezvous
Purge (Integer (ND.TCB (t).R2.I), t); -- remove from callee's q
end if;
if ND.TCB (t).TS = TimedWait then
ND.TCB (t).PC := Defs.Index (ND.TCB (t).R1.I); -- t.out on accept
end if;
ND.TCB (t).TS := Ready;
count := count + 1;
end if;
end loop;
Result := count > 0;
end Wake_Tasks;
procedure ShowTime is null;
procedure SnapShot is null;
procedure Scheduler (CD : Compiler_Data; ND : in out Interpreter_Data) is separate;
procedure Manage_Scheduling (CD : Compiler_Data; ND : in out Interpreter_Data) is
were_tasks_awakened : Boolean;
use Ada.Calendar;
begin
ND.SYSCLOCK := Clock;
if ND.Snap then
ShowTime;
end if;
if ND.TCB (ND.CurTask).TS = Critical then -- SmallAda inter.pas line 456
if ND.Snap then
SnapShot;
end if;
else
Wake_Tasks (CD, ND, were_tasks_awakened);
if ND.SWITCH or else -- ------------> Voluntary release of control
ND.SYSCLOCK >= ND.TIMER or else -- ---> Time slice exceeded
were_tasks_awakened -- ------> Awakened task causes switch
then
if ND.CurTask >= 0 then
ND.TCB (ND.CurTask).LASTRUN := ND.SYSCLOCK;
if ND.TCB (ND.CurTask).TS = Running then
ND.TCB (ND.CurTask).TS := Ready;
-- SWITCH PROCCESS
end if;
end if;
loop -- Call Main Scheduler (SmallAda inter.pas line 479):
Scheduler (CD, ND);
ND.SYSCLOCK := Clock;
if ND.Snap then
ShowTime;
end if;
if ND.Snap then
SnapShot;
end if;
exit when ND.PS /= WAIT;
end loop;
--
if ND.PS = DEADLOCK or ND.PS = FIN then
return;
end if;
--
ND.TIMER := ND.SYSCLOCK + ND.TCB (ND.CurTask).QUANTUM;
ND.TCB (ND.CurTask).TS := Running;
ND.SWITCH := False;
if ND.Snap then
SnapShot;
end if;
end if;
end if;
end Manage_Scheduling;
end HAC_Sys.PCode.Interpreter.Tasking;
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