From dc38515f79696033be87183a1c9da60deacdc4bf Mon Sep 17 00:00:00 2001
From: Lauri Kasanen <cand@gmx.com>
Date: Wed, 18 Aug 2021 15:01:56 +0300
Subject: [PATCH] Add CPUID functions for runtime dispatch

---
 common/rfb/CMakeLists.txt    |  1 +
 common/rfb/EncodeManager.cxx |  1 +
 common/rfb/VNCServerST.cxx   |  4 +++
 common/rfb/cpuid.cxx         | 70 ++++++++++++++++++++++++++++++++++++
 common/rfb/cpuid.h           | 28 +++++++++++++++
 5 files changed, 104 insertions(+)
 create mode 100644 common/rfb/cpuid.cxx
 create mode 100644 common/rfb/cpuid.h

diff --git a/common/rfb/CMakeLists.txt b/common/rfb/CMakeLists.txt
index 38d3472..5e1944f 100644
--- a/common/rfb/CMakeLists.txt
+++ b/common/rfb/CMakeLists.txt
@@ -63,6 +63,7 @@ set(RFB_SOURCES
   VNCServerST.cxx
   ZRLEEncoder.cxx
   ZRLEDecoder.cxx
+  cpuid.cxx
   encodings.cxx
   util.cxx
   xxhash.c)
diff --git a/common/rfb/EncodeManager.cxx b/common/rfb/EncodeManager.cxx
index db3add5..8785190 100644
--- a/common/rfb/EncodeManager.cxx
+++ b/common/rfb/EncodeManager.cxx
@@ -22,6 +22,7 @@
 #include <omp.h>
 #include <stdlib.h>
 
+#include <rfb/cpuid.h>
 #include <rfb/EncCache.h>
 #include <rfb/EncodeManager.h>
 #include <rfb/Encoder.h>
diff --git a/common/rfb/VNCServerST.cxx b/common/rfb/VNCServerST.cxx
index fd13cf3..3dbe9a5 100644
--- a/common/rfb/VNCServerST.cxx
+++ b/common/rfb/VNCServerST.cxx
@@ -53,6 +53,7 @@
 
 #include <network/GetAPI.h>
 
+#include <rfb/cpuid.h>
 #include <rfb/ComparingUpdateTracker.h>
 #include <rfb/KeyRemapper.h>
 #include <rfb/ListConnInfo.h>
@@ -132,6 +133,9 @@ VNCServerST::VNCServerST(const char* name_, SDesktop* desktop_)
 {
   lastUserInputTime = lastDisconnectTime = time(0);
   slog.debug("creating single-threaded server %s", name.buf);
+  slog.info("CPU capability: SSE2 %s, AVX512f %s",
+            supportsSSE2() ? "yes" : "no",
+            supportsAVX512f() ? "yes" : "no");
 
   DLPRegion.enabled = DLPRegion.percents = false;
 
diff --git a/common/rfb/cpuid.cxx b/common/rfb/cpuid.cxx
new file mode 100644
index 0000000..c89f950
--- /dev/null
+++ b/common/rfb/cpuid.cxx
@@ -0,0 +1,70 @@
+/* Copyright (C) 2021 Kasm Web
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+
+#include <stdint.h>
+
+static uint32_t cpuid[4] = { 0 };
+static uint32_t extcpuid[4] = { 0 };
+
+static void getcpuid() {
+	if (cpuid[0])
+		return;
+
+#if defined(__x86_64__) || defined(__i386__)
+	uint32_t eax, ecx = 0;
+
+	eax = 1; // normal feature bits
+
+	__asm__ __volatile__(
+		"cpuid\n\t"
+		: "=a"(cpuid[0]), "=b"(cpuid[1]), "=c"(cpuid[2]), "=d"(cpuid[3])
+		: "0"(eax), "2"(ecx)
+	);
+
+	eax = 7; // ext feature bits
+	ecx = 0;
+
+	__asm__ __volatile__(
+		"cpuid\n\t"
+		: "=a"(extcpuid[0]), "=b"(extcpuid[1]), "=c"(extcpuid[2]), "=d"(extcpuid[3])
+		: "0"(eax), "2"(ecx)
+	);
+#endif
+}
+
+namespace rfb {
+
+bool supportsSSE2() {
+	getcpuid();
+#if defined(__x86_64__) || defined(__i386__)
+	#define bit_SSE2        (1 << 26)
+	return cpuid[3] & bit_SSE2;
+#endif
+	return false;
+}
+
+bool supportsAVX512f() {
+	getcpuid();
+#if defined(__x86_64__) || defined(__i386__)
+	#define bit_AVX512f        (1 << 16)
+	return extcpuid[1] & bit_AVX512f;
+#endif
+	return false;
+}
+
+}; // namespace rfb
diff --git a/common/rfb/cpuid.h b/common/rfb/cpuid.h
new file mode 100644
index 0000000..c84b4a2
--- /dev/null
+++ b/common/rfb/cpuid.h
@@ -0,0 +1,28 @@
+/* Copyright (C) 2021 Kasm Web
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+
+#ifndef __RFB_CPUID_H__
+#define __RFB_CPUID_H__
+
+namespace rfb {
+
+	bool supportsSSE2();
+	bool supportsAVX512f();
+};
+
+#endif