From b6095304b7ee2b69d2ee4a9a7265999d1a2b9675 Mon Sep 17 00:00:00 2001
From: rsc <rsc>
Date: Fri, 10 Aug 2007 16:37:27 +0000
Subject: Make cp a magic symbol.

---
 proc.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

(limited to 'proc.h')

diff --git a/proc.h b/proc.h
index 2848ecd..7a04cd5 100644
--- a/proc.h
+++ b/proc.h
@@ -50,7 +50,17 @@ struct proc {
 //   expandable heap
 
 extern struct proc proc[];
+
+// If xv6 was only for uniprocessors, this could be
+//   struct proc *cp;
+// Instead we have an array curproc, one per
+// processor, and #define cp to the right element
+// in the array.  In general such preprocessor 
+// subterfuge is to be avoided, but cp is used 
+// so often that having the shorthand is worth the ugliness.
 extern struct proc *curproc[NCPU];  // Current (running) process per CPU
+#define cp (curproc[cpu()])  // Current process on this CPU
+
 
 #define MPSTACK 512
 
-- 
cgit v1.2.3