patch-2.2.8 linux/include/asm-arm/proc-armv/semaphore.h

• Lines: 33
• Date: Sat May 8 11:06:58 1999
• Orig file: v2.2.7/linux/include/asm-arm/proc-armv/semaphore.h
• Orig date: Fri Jan 8 22:36:23 1999

diff -u --recursive --new-file v2.2.7/linux/include/asm-arm/proc-armv/semaphore.h linux/include/asm-arm/proc-armv/semaphore.h
@@ -60,6 +60,32 @@
 	return temp;
 }
 
+extern inline int down_trylock(struct semaphore *sem)
+{
+	unsigned int cpsr, temp;
+
+	__asm__ __volatile__ ("
+	@ atomic down try lock operation
+	mrs	%0, cpsr
+	orr	%1, %0, #128		@ disable IRQs
+	bic	%0, %0, #0x80000000	@ clear N
+	msr	cpsr, %1
+	ldr	%1, [%2]
+	subs	%1, %1, #1
+	orrmi	%0, %0, #0x80000000	@ set N
+	str	%1, [%2]
+	msr	cpsr, %0
+	movmi	r0, %2
+	movpl	r0, #0
+	blmi	" SYMBOL_NAME_STR(__down_trylock_failed) "
+	mov	%1, r0"
+		: "=&r" (cpsr), "=&r" (temp)
+		: "r" (sem)
+		: "r0", "lr", "cc");
+
+	return temp;
+}
+
 /*
  * Note! This is subtle. We jump to wake people up only if
  * the semaphore was negative (== somebody was waiting on it).