as of 2013-10-172013-10-17

1 files changed, 19 insertions, 3 deletions

diff --git a/pcb.c b/pcb.c
index 8f4034a..c383a37 100644
--- a/pcb.c
+++ b/pcb.c
@@ -2,6 +2,12 @@
 #include <string.h>

 #include <stdio.h>

 

+#define STK_PSW    (STACK_SIZE - 1)

+#define STK_CS     (STACK_SIZE - 2)

+#define STK_IP     (STACK_SIZE - 3)

+#define STK_DS     (STACK_SIZE - 9)

+#define INIT_STACK (STACK_SIZE - 12)

+

 /**

  * Returns the address of the PCB with the specified name

  */

@@ -54,7 +60,7 @@ int free_pcb(pcb * list, pcb * addr) {
 		return -2;

 	  } else {

 		// we need to free the PCB

-		build_pcb(current, "        ", 0, -1, -1, 0);

+		build_pcb(current, "        ", 0, -1, -1, 0, NULL, NULL, NULL, NULL);

 		return 1;

 	  }

 	}

@@ -69,7 +75,8 @@ int free_pcb(pcb * list, pcb * addr) {
  * Sets the properties of the given PCB.

  */

 int build_pcb(pcb * addr, char name[], int type, int state,

-			  int suspend, int priority) {

+			  int suspend, int priority, unsigned cs, unsigned ip,

+			  unsigned ds, unsigned psw) {

   // check that address is valid

   if (addr == 0 || addr == NULL) {

 	return -1;

@@ -99,6 +106,13 @@ int build_pcb(pcb * addr, char name[], int type, int state,
   addr->prev = NULL;

   addr->priority = priority;

 

+  // set up the stack

+  addr->stack[STK_PSW] = psw;

+  addr->stack[STK_CS] = cs;

+  addr->stack[STK_IP] = ip;

+  addr->stack[STK_DS] = ds;

+

+  addr->stack_ptr =(unsigned) &(addr->stack[INIT_STACK]);

   return 1;

 }

 

@@ -172,7 +186,9 @@ int remove_pcb(pcb **queue, pcb * addr) {
   // are we removing the head?

   if (addr == *queue) {

 	*queue = addr->next;

-	(addr->next)->prev = NULL;

+	if (addr->next != NULL) {

+	  (addr->next)->prev = NULL;

+	}

 	return 0;

   }