Updated Solutions

assignment-1/Makefile

@@ -0,0 +1,6 @@
+.c.o:
+		gcc -c $*.c
+hello:	main.o dumb.o
+		gcc -o hello main.o dumb.o
+main.o:	main.c dumb.h
+dumb.o:	dumb.c	dumb.h

assignment-1/dumb.c

@@ -0,0 +1,7 @@
+#include<stdio.h>
+#include "dumb.h"
+
+void dumb(int n, int m)
+{
+  printf("n*m = %d\n", n*m);
+}

assignment-1/dumb.h

@@ -0,0 +1 @@
+void dumb(int n, int m);

assignment-1/main.c

@@ -0,0 +1,9 @@
+#include<stdio.h>
+#include "dumb.h"
+int main()
+{
+  printf("%s", "Hello World!\n");
+  dumb(23,3);
+
+  return 0;
+}

assignment-1/myhello.c

@@ -0,0 +1,12 @@
+#include<stdio.h>
+#include "myhello.h"
+int main()
+/* this is a comment */
+{
+	int i;
+	/* What is the statement below doing?*/
+	printf("%s", "Hello World!\n");
+	i = VAL;
+	printf("%d \n", i);
+	return 0;
+}

assignment-1/myhello.h

@@ -0,0 +1 @@
+const int VAL = 3;

assignment-1/test/Makefile

@@ -0,0 +1,4 @@
+.c.o:
+		gcc -c -g $*.c
+test:	test.o
+		gcc -o test test.o

assignment-1/test/test.c

@@ -0,0 +1,9 @@
+#include<stdio.h>
+
+int main(){
+  int i=23;
+  //scanf("Input a number: ",%i);
+  int m = i*i;
+  printf("Square of %d is: %d\n", i, m);
+  return 0;
+}

solutions/lab-2/scheduler - commented

@@ -0,0 +1,40 @@
+void
+scheduler(void)
+{
+  struct proc *p;
+  struct cpu *c = mycpu();
+  c->proc = 0;
+
+  for(;;){
+    // Enable interrupts on this processor.
+    // STI — Set Interrupt Flag
+    sti();
+
+    // Loop over process table looking for process to run.
+    acquire(&ptable.lock);
+    // the &ptable.proc[NPROC] is the address of the last element of the ptable.proc array.
+    for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
+      if(p->state != RUNNABLE)
+        continue;
+
+      // Switch to chosen process.  It is the process's job
+      // to release ptable.lock and then reacquire it
+      // before jumping back to us.
+      c->proc = p;
+      // the switchuvm(p) will do the switching of the kernel virtual memory to the process's virtual memory.
+      switchuvm(p);
+      p->state = RUNNING;
+      // Now the process is running, so we can switch to it.
+      // The swtch(&(c->scheduler), p->context)  is the content switch. It will save the current context and load the new context.
+      swtch(&(c->scheduler), p->context);
+      // The switchkvm function will switch the kernel virtual memory to the process's virtual memory.
+      switchkvm();
+
+      // Process is done running for now.
+      // It should have changed its p->state before coming back.
+      c->proc = 0;
+    }
+    release(&ptable.lock);
+
+  }
+}