diff options
Diffstat (limited to 'pcb.c')
| -rw-r--r-- | pcb.c | 22 |
1 files changed, 19 insertions, 3 deletions
@@ -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;
}
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