Sse scaling (#52)

* Add CPUID functions for runtime dispatch
* Add SSE2 scaling

common/rfb/scale_sse2.h

@@ -0,0 +1,38 @@
+/* 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_SCALE_SSE2_H__
+#define __RFB_SCALE_SSE2_H__
+
+#include <stdint.h>
+
+namespace rfb {
+
+	void SSE2_halve(const uint8_t *oldpx,
+			const uint16_t tgtw, const uint16_t tgth,
+			uint8_t *newpx,
+			const unsigned oldstride, const unsigned newstride);
+
+	void SSE2_scale(const uint8_t *oldpx,
+			const uint16_t tgtw, const uint16_t tgth,
+			uint8_t *newpx,
+			const unsigned oldstride, const unsigned newstride,
+			const float tgtdiff);
+};
+
+#endif