2 files changed, 46 insertions, 4 deletions
diff --git a/src/userprog/process.c b/src/userprog/process.c
index b3e16bb..45aaaa4 100644
--- a/src/userprog/process.c
+++ b/src/userprog/process.c
@@ -88,7 +88,7 @@ start_process (void *file_name_)
 int
 process_wait (tid_t child_tid UNUSED) 
 {
-  return -1;
+  for (;;) {}
 }
 
 /* Free the current process's resources. */
@@ -476,7 +476,7 @@ setup_stack (void **esp)
     {
       success = install_page (((uint8_t *) PHYS_BASE) - PGSIZE, kpage, true);
       if (success)
-        *esp = PHYS_BASE;
+        *esp = PHYS_BASE - 12;
       else
         palloc_free_page (kpage);
     }
diff --git a/src/userprog/syscall.c b/src/userprog/syscall.c
index 370c89b..5e5a6f1 100644
--- a/src/userprog/syscall.c
+++ b/src/userprog/syscall.c
@@ -4,6 +4,10 @@
 #include "threads/interrupt.h"
 #include "threads/thread.h"
 
+#include "threads/init.h"
+#include "filesys/filesys.h"
+#include "filesys/off_t.h"
+
 static void syscall_handler (struct intr_frame *);
 
 void
@@ -12,9 +16,47 @@ syscall_init (void)
   intr_register_int (0x30, 3, INTR_ON, syscall_handler, "syscall");
 }
 
+// cast to TYPE and deref argument N from f->esp
+#define INTR_ESP(N, TYPE) *(TYPE *)(f->esp+(4*(N)))
+
 static void
 syscall_handler (struct intr_frame *f UNUSED) 
 {
-  printf ("system call!\n");
-  thread_exit ();
+  int syscall_number = INTR_ESP(0, int);
+  switch (syscall_number) {
+    case 0:
+      // halt
+      power_off ();
+      break;
+    case 1:
+      // exit
+      break;
+    case 4:
+      // create
+      ; // empty statement because c-grammar doesn't allow declarations following labels
+      printf("kernel: create\n");
+      char *filename = INTR_ESP(1, char *);
+      printf("create: read filename '%s'\n", filename);
+      off_t initial_size = INTR_ESP(2, off_t);
+      printf("create: read initial_size '%d'\n", initial_size);
+      f->eax = filesys_create(filename, initial_size);
+      printf("create: result (%d) put in f->eax\n", f->eax);
+      break;
+    case 6:
+      // open
+      break;
+    case 8:
+      // read
+      break;
+    case 9:
+      // write
+      printf ("printf: %s", INTR_ESP(2, char *));
+      break;
+    case 12:
+      // close
+      break;
+    default:
+      printf ("kernel: unknown syscall '%d'\n", syscall_number);
+      break;
+  }
 }