(svn r4125) - Feature: Add a general TIC() TOC() mechanism using rdtsc or something similar on non-i386 architectures to performance-tune (critical) code. Some systems are probably missing, but those can be added later.

os_timer.c

@@ -0,0 +1,69 @@
+#include "stdafx.h"
+
+#undef RDTSC_AVAILABLE
+
+/* rdtsc for MSC_VER, uses simple inline assembly, or _rdtsc
+ * from external win64.asm because VS2005 does not support inline assembly */
+#if defined(_MSC_VER) && !defined(RDTSC_AVAILABLE)
+# if defined (_M_AMD64)
+extern uint64 _rdtsc(void);
+#	else
+uint64 _declspec(naked) _rdtsc(void) 
+{
+	_asm {
+		rdtsc
+		ret
+	}
+}
+# endif
+# define RDTSC_AVAILABLE
+#endif
+
+/* rdtsc for OS/2. Hopefully this works, who knows */
+#if defined (__WATCOMC__) && !defined(RDTSC_AVAILABLE)
+unsigned __int64 _rdtsc( void);
+# pragma aux _rdtsc = 0x0F 0x31 value [edx eax] parm nomemory modify exact [edx eax] nomemory;
+# define RDTSC_AVAILABLE
+#endif
+
+/* rdtsc for all other *nix-en (hopefully). Use GCC syntax */
+#if defined(__i386__) || defined(__x86_64__) && !defined(RDTSC_AVAILABLE)
+uint64 _rdtsc(void)
+{
+	uint32 high, low;
+	__asm__ __volatile__ ("rdtsc" : "=a" (low), "=d" (high));
+	return ((uint64)high << 32) | low;
+}
+# define RDTSC_AVAILABLE
+#endif
+
+/* rdtsc for PPC which has this not */
+#if defined(__POWERPC__) && !defined(RDTSC_AVAILABLE)
+uint64 _rdtsc(void)
+{
+	uint32 high, low;
+	uint32 high2 = 0;
+	/* PPC does not have rdtsc, so we cheat by reading the two 32-bit time-counters
+	 * it has, 'Move From Time Base (Upper)'. Since these are two reads, in the
+	 * very unlikely event that the lower part overflows to the upper part while we
+	 * read it; we double-check and reread the registers */
+	asm volatile (
+				  "mftbu %0\n"
+				  "mftb %1\n"
+				  "mftbu %2\n"
+				  "cmpw %3,%4\n"
+				  "bne- $-16\n"
+				  : "=r" (high), "=r" (low), "=r" (high2)
+				  : "0" (high), "2" (high2)
+				  );
+	return ((uint64)high << 32) | low;
+}
+# define RDTSC_AVAILABLE
+#endif
+
+/* In all other cases we have no support for rdtsc. No major issue,
+ * you just won't be able to profile your code with TIC()/TOC() */
+#if !defined(RDTSC_AVAILABLE)
+#warning "OS has no support for rdtsc()"
+uint64 _rdtsc(void) {return 0;}
+#endif