[joyos] r297 committed - Added non-stub fork routine.

[jo...@googlecode.com]

Revision: 297
Author: vaumnou
Date: Tue Jan 18 00:50:55 2011
Log: Added non-stub fork routine.
http://code.google.com/p/joyos/source/detail?r=297

Modified:
/trunk/src/kern/fork.c

=======================================
--- /trunk/src/kern/fork.c Mon Apr 19 21:40:36 2010
+++ /trunk/src/kern/fork.c Tue Jan 18 00:50:55 2011
@@ -36,6 +36,10 @@
#include <kern/global.h>
#include <avr/interrupt.h>
#include <setjmp.h>
+#include <string.h>
+
+extern struct thread *current_thread;
+extern struct thread threads[MAX_THREADS];

// Duplicate this thread (with it's own stack).
// In the parent thread, this returns the thread id (tid) of the child.
@@ -43,37 +47,31 @@
int fork (void) {

panic("fork");
-
- struct thread *child;
-
- // record interrupt status
- uint8_t was_enabled = SREG & SREG_IF;
- // lock thread table
- cli();
+ // pause scheduling
+ ATOMIC_BEGIN;

// allocate new thread for child
- child = NULL; // FIXME
-
- // copy state to child thread
- //if (setjmp(child->th_jmpbuf) != 0) {
- if (setjmp(TO_JMP_BUF(child->th_jmpbuf)) != 0) {
- // we're the child now and we've just been scheduled
- // interrupts should be enabled
-
- // fork returns 0
- return 0;
- }
-
- // allocate child stack and copy contents of parent stack
-
- // enable child thread
- child->th_status = THREAD_RUNNABLE;
-
- // restore interrupt status
- SREG |= was_enabled;
-
- // we're the parent and our work is done, we're ready to return
- return child->th_id;
+ int i = create_thread(current_thread->th_func,
current_thread->th_stacksize, current_thread->th_priority,
current_thread->th_name);
+
+ uint16_t child_sp, parent_sp, size;
+
+ // get stack pointers
+ parent_sp = SP;
+ size = current_thread->th_stacktop - parent_sp;
+ child_sp = threads[i].th_stacktop - size;
+
+ // copy stack to child
+ memcpy((void*)(child_sp + 1), (const void *)(parent_sp + 1), size);
+
+ // patch child jump buffer
+ threads[i].th_jmpbuf.sp = child_sp;
+ threads[i].th_jmpbuf.pc = (uint16_t)&&label_ret;
+
+ ATOMIC_END;
+ return i; // under what conditions might this be zero?
+label_ret:
+ ATOMIC_END;
+ return 0;
}

#endif