patch-2.1.104 linux/include/linux/delay.h

• Lines: 28
• Date: Thu May 21 14:24:09 1998
• Orig file: v2.1.103/linux/include/linux/delay.h
• Orig date: Sat Nov 29 15:08:21 1997

diff -u --recursive --new-file v2.1.103/linux/include/linux/delay.h linux/include/linux/delay.h
@@ -11,4 +11,27 @@
 
 #include <asm/delay.h>
 
+/*
+ * Using udelay() for intervals greater than a few milliseconds can
+ * risk overflow for high loops_per_sec (high bogomips) machines. The
+ * mdelay() provides a wrapper to prevent this.  For delays greater
+ * than MAX_UDELAY_MS milliseconds, the wrapper is used.  Architecture
+ * specific values can be defined in asm-???/delay.h as an override.
+ * The 2nd mdelay() definition ensures GCC will optimize away the 
+ * while loop for the common cases where n <= MAX_UDELAY_MS  --  Paul G.
+ */
+
+#ifndef MAX_UDELAY_MS
+#define MAX_UDELAY_MS	5
+#endif
+
+#ifdef notdef
+#define mdelay(n) (\
+	{unsigned long msec=(n); while (msec--) udelay(1000);})
+#else
+#define mdelay(n) (\
+	(__builtin_constant_p(n) && (n)<=MAX_UDELAY_MS) ? udelay((n)*1000) : \
+	({unsigned long msec=(n); while (msec--) udelay(1000);}))
+#endif
+
 #endif /* defined(_LINUX_DELAY_H) */