# HG changeset patch
# User John Floren <john@jfloren.net>
# Date 1328740711 0
# Node ID 34ea01195f9f3c474ccda369eefcf36aa2cc816f
# Parent  29403dfab2b1296d30ab2d13a911baec90fa0845
sysproc.c: restore tsemacquire to its former glory

R=nix-dev
CC=nemo, nix-dev, nixiedev
http://codereview.appspot.com/5644061

diff -r 29403dfab2b1 -r 34ea01195f9f sys/src/nix/port/sysproc.c
--- a/sys/src/nix/port/sysproc.c	Wed Feb 08 22:33:03 2012 +0100
+++ b/sys/src/nix/port/sysproc.c	Wed Feb 08 22:38:31 2012 +0000
@@ -1180,6 +1180,53 @@
 	return 1;
 }
 
+/* Acquire semaphore or time-out */
+static int
+tsemacquire(Segment* s, int* addr, ulong ms)
+{
+	int acquired;
+	Sema phore;
+	int timedout;
+	ulong t;
+
+	if(canacquire(addr))
+		return 1;
+	if(ms == 0)
+		return 0;
+
+	acquired = 0;
+	timedout = 0;
+	semqueue(s, addr, &phore);
+	for(;;){
+		phore.waiting = 1;
+		coherence();
+		if(canacquire(addr)){
+			acquired = 1;
+			break;
+		}
+		if(waserror())
+			break;
+		t = m->ticks;
+		tsleep(&phore, semawoke, &phore, ms);
+		if(TK2MS(m->ticks-t) >= ms) {
+			timedout = 1;
+			poperror();
+			break;
+		}
+		ms -= TK2MS(m->ticks-t);
+		poperror();
+	}
+	semdequeue(s, &phore);
+	coherence();	/* not strictly necessary due to lock in semdequeue */
+	if(!phore.waiting)
+		semwakeup(s, addr, 1);
+	if(timedout)
+		return 0;
+	if(!acquired)
+		nexterror();
+	return 1;
+}
+
 void
 syssemacquire(Ar0* ar0, va_list list)
 {
@@ -1205,6 +1252,30 @@
 }
 
 void
+systsemacquire(Ar0* ar0, va_list list)
+{
+	Segment *s;
+	int *addr, ms;
+
+	/*
+	 * int tsemacquire(long* addr, ulong ms);
+	 * should be (and will be implemented below as) perhaps
+	 * int tsemacquire(int* addr, ulong ms);
+	 */
+	addr = va_arg(list, int*);
+	addr = validaddr(addr, sizeof(int), 1);
+	evenaddr(PTR2UINT(addr));
+	ms = va_arg(list, ulong);
+
+	if((s = seg(up, PTR2UINT(addr), 0)) == nil)
+		error(Ebadarg);
+	if(*addr < 0)
+		error(Ebadarg);
+
+	ar0->i = tsemacquire(s, addr, ms);
+}
+
+void
 syssemrelease(Ar0* ar0, va_list list)
 {
 	Segment *s;