commit before merging

.vscode/settings.json

 {
     "files.associations": {
         "task-descriptor.h": "c",
-        "bwio.h": "c"
+        "bwio.h": "c",
+        "kernel.h": "c",
+        "scheduler.h": "c",
+        "k1.h": "c"
     }
 }
\ No newline at end of file

include/context-switch.h

@@ -3,6 +3,6 @@
 
 void kerent();
 
-Request* kerxit(TD* Active);
+void kerxit(TD* Active);
 
 #endif
\ No newline at end of file

include/k1.h

+#ifdef K1_H
+#ifndef K1_H
+
+void someK1Fn();
+
+void firstUserTaskChildren();
+
+#endif
\ No newline at end of file

include/kernel.h

@@ -2,23 +2,27 @@
 #define KERNEL_H
 
 #define MAX_NUM_PRIORITY 8
-#define MAX_NUM_TD 10
+#define MAX_NUM_TD 60
 
+#define KERNEL_STACK (0xFFFFFFFF - 0x200000)
 
 typedef struct kernel {
     TDPQ* ArrayPQ[MAX_NUM_PRIORITY];
-    int AliveTasks[MAX_NUM_TD]; //index is TaskID; value of 1 = alive
+    TD Tasks[MAX_NUM_TD];
+     //index is TaskID; value of 1 = alive
     // a free list of pointers to free TDs. This might take the form of bits set in a couple of words. WHAT?
     // a structure for keeping the request currently being serviced, including its arguments.
-    Request syscalReq;
+    TD* FirstOfFreeList;
+    TD* LastOfFreeList;
     TD* Active;
+    int NumTDsAvail;
 }KernelStruct;
 
 
 void kernelInit (KernelStruct* Colonel);
 
-void activate(KernelStruct* Colonel); // TODO Will have to return a request
+int activate(KernelStruct* Colonel); 
 
-void handle(KernelStruct* Colonel, Request* syscallRequest);
+void handle(KernelStruct* Colonel, int syscallRequest);
 
 #endif

include/scheduler.h

 #ifndef SCHEDULER_H
 #define SCHEDULER_H
 
-int schedulerInit(); // add the IDLE task with lowest priority and first USER task maybe
+int schedulerInit(KernelStruct* Colonel); 
 
 int pushToScheduler (KernelStruct* Colonel, TD* Task);
 

include/syscall-handler.h

@@ -7,11 +7,11 @@ typedef enum syscall {
     SYS_ParentTid,
     SYS_Pass,
     SYS_Exit
-} Syscall;
+}Syscall;
 
 void handlerCreate (TD* Active);
 
-int syscallHandler (KernelStruct* Colonel, TD* Active);
+int syscallHandler (KernelStruct* Colonel);
 
 #endif
 

include/task-descriptor.h

 #ifndef TASK_DESCRIPTOR_H
 #define TASK_DESCRIPTOR_H
 
-#define USER_STACK_SIZE  1024*64 // 64KB 
+#define STACK_SIZE 0x80000 // 512KB 
+#define USER_STACK_TOP (0xFFDFFFFF - STACK_SIZE)
 
 typedef enum taskstate {
     Active, 
     Ready, 
-    Blocked
+    Blocked,
+    Init
 }State;
 
 typedef enum prioritylvl {
@@ -23,24 +25,24 @@ typedef enum prioritylvl {
 struct taskDescriptor {
     int TaskID;
     int ParentID;
-
     State TaskState;
+    PrioLvl TaskPriority; 
+
+    struct taskDescriptor* NextFree;
+    struct taskDescriptor* NextInPQ; 
     
-    int* spsr;
+    int spsr; //
     int* lr;
-    int* sp; 
-    
-    struct taskDescriptor* Next;
+    int* sp; // 
+    int RetVal; //
 
-    PrioLvl TaskPriority; 
-    struct taskDescriptor* Parent;
-//    Request* Req;
-    void* RetVal;
 };
 
 typedef struct taskDescriptor TD;
 
-TD* TDinit(PrioLvl Priority);
+TD* CreateTask(KernelStruct* Colonel, PrioLvl Priority);
+
+void RemoveTask(KernelStruct* Colonel, TD* Task);
 
 int isTaskAlive(int TaskID);
 

lib/kernel.c

@@ -3,14 +3,35 @@
 #include "kernel.h"
 
 void kernelInit(KernelStruct* Colonel) {
+    int i;
+    TD* temp;
 
+    for (i = 0; i < MAX_NUM_TD; i++) {
+        temp = &(Colonel->Tasks[i]);
+        temp->TaskID = i;
+        temp->ParentID = 0;
+        temp->TaskState = Init;
+        temp->TaskPriority = Prio0;
+
+        if (i == MAX_NUM_TD-1) temp->NextFree = NULL;
+        else temp->NextFree = &(Colonel->Tasks[i+1]);
+        temp->NextInPQ = NULL;
+
+        temp->sp = USER_STACK_TOP - (STACK_SIZE*i);
+        temp->spsr = 208; // or 0xd0;
+        temp->RetVal = 0;
+        temp->lr = 0;
+    }
+    Colonel->FirstFree = &(Colonel->Tasks[0]);
+    Colonel->LastFree = &(Colonel->Tasks[MAX_NUM_TD-1]);
+    Colonel->NumTDsAvail = MAX_NUM_TD;
 }
 
 
 void activate(KernelStruct* Colonel, TD* Active) {
-    
+    kerxit(Active);
 }
 
 void handle(KernelStruct* Colonel,  Request* syscallRequest) {
-    
+        
 };
\ No newline at end of file

lib/syscall-handler.c

@@ -2,26 +2,29 @@
 #include "kernel.h"
 #include "syscall-handler.h"
 
-int handlerCreate(TD* Active, int priority, fn_ptr) {
-    if 
-}
 
 
+int handlerCreate(KernelStruct* Colonel, TD* Active, int priority, void (*code)()) {
+
+    TD* NewTask = NewTask(priority,Active->TaskID),code);
+    return pushToScheduler(Colonel, NewTask);
+}
+
 
 int handle(TD* Active, Request* req) {
     switch(req->n) {
         case SYS_Create:
-            return handlerCreate(Active);
+            return handlerCreate(Active, Active->TaskPriority, ???); // TODO
         case SYS_MyTid:
             return Active->TaskID;
         case SYS_ParentTid:
-            if (isTaskAlive(Active->ParentID)) return Active->ParentID;
-            else return -1;
+            if (isTaskAlive(Active->ParentID))  return Active->ParentID;
+            else return FAILURE;
         case SYS_Pass:
             Active->TaskState = Ready;
-            return 0;
+            return SUCCESS;
         case SYS_Exit:
-            // TODO
+            
 
     }
 }

lib/syscall.c

@@ -2,7 +2,11 @@
 #include "syscall.h"
 
 int Create (int priority, void (*code)()) {
-    asm volatile ("swi %0" : "r" (SYS_Create));
+    asm volatile (
+    //    "stmfd sp!, {r0, r1}\n\t"
+        "swi %0" : "r" (SYS_Create)
+    //    "ldmfd sp!, {r1, r2}\n\t" 
+    );
     register int RetVal asm("r0");
     return RetVal;
     // return TaskID of new Task

lib/task-descriptor.c

 #include "task-descriptor.h"
 
+TD* TDinit(KernelStruct* Colonel, PrioLvl Priority, int TaskID, int ParentID) {
 
+<<<<<<< HEAD
 int TaskInit();
+=======
+  TD* Task = &(Colonel->Tasks[TaskID]);
+
+  Task->TaskID = TaskID;
+  Task->ParentID = ParentID;
+  Task->TaskState = Active;
+  Task->TaskPriority = Priority;
+  Task->sp = NULL;
+  Task->lr = NULL;
+  Task->spsr = 0;
+  Task->RetVal = 0;
+
+  return Task;
+}
+
+TD* CreateTask(KernelStruct* Colonel, PrioLvl Priority, int code) {
+    if (Colonel->NumTDsAvail == 0) return NULL;
+    TD* NewTask = Colonel->FirstFree;
+
+    Colonel->FirstOfFreeList = NewTask->NextFree;
+    NewTask->NextFree = NULL;
+
+
+    NewTask->TaskState = Ready;
+    NewTask->TaskPriority = Priority;
+    NewTask->TaskID = // TODO
+    if (Colonel->Active == NULL) NewTask->ParentID = 0;
+    else NewTask->ParentID = (Colonel->Active)->TaskID;
+
+    Colonel->NumTDsAvail -= 1;
+    
+    return NewTask;
+}
+
+void RemoveTask(KernelStruct* Colonel, TD* Task) {} // IF NECESSARY
+>>>>>>> 698d3cdd94aa71c7ae90252230240feed1876156
 
 int isTaskAlive(int TaskID) {
   return TaskID >> 31;
@@ -14,11 +52,13 @@ int GetGeneration(TD* Task) {
   return ((TID << 1) >> 17);
 }
 
+// to see if this task is active
 int GetAvailability(TD* Task) {
   int mask = 1 <<31;
   return mask & (Task->TaskID);
 }
 
+// for sp calculation
 int GetMemoryIndex(TD* Task){
   int mask = 1 << 16 - 1;
   return mask & (Task->TaskID);

src/context-switch.s

@@ -15,7 +15,7 @@ kerent:
 	msr cpsr_c, #0xDF  @or #223
 
 	@ push register contents onto users stack
-	stmfd sp!, {r4-r14}
+	stmfd sp!, {r0-r14}
 
 	@ save user's sp 
 	mov r3, sp
@@ -30,8 +30,7 @@ kerent:
 	str r3!, {r2, r1}
 
 	@ pop kernels stack
-	ldmfd sp!, {r3-r12, lr}
-
+	ldmfd sp!, {r4-r14}
 
 
 	.text
@@ -46,12 +45,14 @@ kerxit:
 
 	@ push kernel's registers
 	stmfd sp!, {r4-r14}
-
+	@ stmfd sp_svc!, {r0-r14} TODO
 	@ switching to system mode
 	msr cpsr_c, #0xDF 
 
-	@ restore user's sp, spsr and lr
-
+	@ restore user's spsr and lr
+	ldr r1, [sp, #0] @ lr
+	ldr r2, [sp, #4] @ spsr
+	sub sp, sp, #4
 
 	@ restore user's registers
 	ldmfd sp!, {r4-r14}
@@ -60,7 +61,7 @@ kerxit:
 	msr cpsr, #0xD3
 
 	@ restore user's spsr
-	msr spsr, r3
+	msr spsr, r2
 	
 	@ restore user's lr to continue execution; also put spsr_svc into cpsr
 	movs pc, r1 

src/k1.c

@@ -9,14 +9,18 @@ void someK1Fn() {
 
 void firstUserTaskChildren() {
     int TaskID;
-    TaskID = Create(Prio1, someK1Fn);
+    TaskID = Create(Prio1, &someK1Fn);
     bwprintf(COM2, "Created: <%d>\n", TaskID);
-    TaskID = Create(Prio1, someK1Fn);
+
+    TaskID = Create(Prio1, &someK1Fn);
     bwprintf(COM2, "Created: <%d>\n", TaskID);
-    TaskID = Create(Prio5, someK1Fn);
+
+    TaskID = Create(Prio5, &someK1Fn);
     bwprintf(COM2, "Created: <%d>\n", TaskID);
-    TaskID = Create(Prio5, someK1Fn);
+
+    TaskID = Create(Prio5, &someK1Fn);
     bwprintf(COM2, "Created: <%d>\n", TaskID);
     bwprintf(COM2, "FirstUserTask: exiting");
+
     Exit();
 }
\ No newline at end of file

src/main.c

 // #include "kernel.h"
 #include "task-descriptor.h"
 #include "scheduler.h"
-// #include "error.h"
+#include "k1.h"
 #include "bwio.h"
 #include "request.h"
 
 #define FOREVER while(1)
 
 
-// void kerent() {
-
-// }
-
-// void kerxit(TD* Active, Request* req) {
-//     bwprintf(COM2, "kerxit.c: Hello\n\r");
-//     bwprintf(COM2, "kerxit.c: Activating\n\r");
-//     kerent();
-//     bwprintf(COM2, "kerxit.c: Goodbye\n\r");  
-// }
-
-// void initialize(TD* Active) {
-
-// }
-
-// void handle(TD* Active, Request* req) {
-
-// }
-
 int main(int argc, char const *argv[])
 {
     KernelStruct Colonel;
     Request* Req; 
     int i, Status;
 
+    int* kernelEntry = (int *)(0x8);
+    *kernelEntry = (int)&kerent;
+    
+    kernelInit(&Colonel); 
     schedulerInit();
     memoryInit();
-    kernelInit(&Colonel); // which will call kerent;
-    // disableInterrupts();
-    Colonel->Active = Create(Prio4, firstUserTaskChildren);
-    // tds is an array of TDs
-    for (i = 0; i < 4; i++ ) {
-        Colonel->Active = getNextTaskScheduler(Colonel);
-        Req = kerxit(Active);
-        Status = handle(Active, Req);
-    }
-    return 0;
-
+    
 
+    Colonel->Active = Create(Prio4, &firstUserTaskChildren);
 
+    return 0;
 
 }

src/scheduler.c

-#include "scheduler.h"
-
-// int schedulerInit() {
-//     return 0;
-// } // add the IDLE task with lowest priority and first USER task maybe
-
-// int pushToScheduler (KernelStruct* Colonel, TD* Task) {
-//     return 0;
-// }
-
-// TD* getNextTaskScheduler (KernelStruct* Colonel) {
-//     return NULL;
-// }

src/task-descriptor.c

-#include "task-descriptor.h"
-
-
-//void TaskInit();
-
-int isTaskAlive(int TaskID) {
-    return 0;
-}
-
-
-
-
-
-