1 files changed, 39 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/gpxe/src/arch/i386/include/gpxe/rdtsc_timer.h b/contrib/syslinux-4.02/gpxe/src/arch/i386/include/gpxe/rdtsc_timer.h
new file mode 100644
index 0000000..67ba22f
--- /dev/null
+++ b/contrib/syslinux-4.02/gpxe/src/arch/i386/include/gpxe/rdtsc_timer.h
@@ -0,0 +1,39 @@
+#ifndef _GPXE_RDTSC_TIMER_H
+#define _GPXE_RDTSC_TIMER_H
+
+/** @file
+ *
+ * RDTSC timer
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#ifdef TIMER_RDTSC
+#define TIMER_PREFIX_rdtsc
+#else
+#define TIMER_PREFIX_rdtsc __rdtsc_
+#endif
+
+/**
+ * RDTSC values can easily overflow an unsigned long.  We discard the
+ * low-order bits in order to obtain sensibly-scaled values.
+ */
+#define TSC_SHIFT 8
+
+/**
+ * Get current system time in ticks
+ *
+ * @ret ticks		Current time, in ticks
+ */
+static inline __always_inline unsigned long
+TIMER_INLINE ( rdtsc, currticks ) ( void ) {
+	unsigned long ticks;
+
+	__asm__ __volatile__ ( "rdtsc\n\t"
+			       "shrdl %1, %%edx, %%eax\n\t"
+			       : "=a" ( ticks ) : "i" ( TSC_SHIFT ) : "edx" );
+	return ticks;
+}
+
+#endif /* _GPXE_RDTSC_TIMER_H */