HTTP/2 (reopened #694)

tempesta_fw/http2/bits.h

@@ -0,0 +1,134 @@
+/**
+ *		Tempesta FW
+ *
+ * Basic bit manipulations.
+ *
+ * Copyright (C) 2017 Tempesta Technologies, Inc.
+ *
+ * This program 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 program 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 program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) Julius Goryavsky. Original code of this module
+ * is granted by the author for unrestricted use in the Tempesta FW
+ * and for distribution under GNU General Public License without
+ * any restrictions.
+ */
+
+#ifndef BITS_H
+#define BITS_H
+
+#include "common.h"
+
+#define Bit_Sub -
+#define Bit_High(x, n) (x) >= (1U << n)
+
+#ifdef __GNUC__
+
+#if Platform_64bit
+
+#define Bit_CRC(crc, x) \
+   (__extension__ ({ \
+      register uintptr_t __r = crc; \
+      __asm__( \
+	 "crc32q %2,%0" : "=r" (__r) : "0" (__r), "rm" ((uintptr_t) x) : "cc" \
+      ); \
+      __r; \
+   }))
+
+#define Bit_FastLog2(x) \
+   (__extension__ ({ \
+      register uintptr_t __r; \
+      __asm__( \
+	 "bsrq %1,%0" : "=r" (__r) : "rm" ((uintptr_t) x) : "cc" \
+      ); \
+      __r; \
+   }))
+
+#else
+
+#define Bit_CRC(crc, x) \
+   (__extension__ ({ \
+      register uintptr_t __r = crc; \
+      __asm__( \
+	 "crc32 %2,%0" : "=r" (__r) : "0" (__r), "rm" ((uintptr_t) x) : "cc" \
+      ); \
+      __r; \
+   }))
+
+#define Bit_FastLog2(x) \
+   (__extension__ ({ \
+      register uintptr_t __r; \
+      __asm__( \
+	 "bsr %1,%0" : "=r" (__r) : "rm" ((uintptr_t) x) : "cc" \
+      ); \
+      __r; \
+   }))
+
+#endif
+
+#else
+
+common_inline unsigned int
+Bit_FastLog2(uintptr_t value)
+{
+	unsigned int x = (unsigned int)value;
+	unsigned int n = 0;
+
+#ifdef Platform_64bit
+	if (Bit_High(value, 32)) {
+		x = (unsigned int)(value >> 32);
+		n = 32;
+	}
+	if (Bit_High(x, 16))
+		x = x >> 16, n += 16;
+#else
+	if (Bit_High(x, 16))
+		x = x >> 16, n = 16;
+#endif
+#ifndef Branch_Free
+	if (x >= 256)
+		x = x >> 8, n += 8;
+	if (x >= 16)
+		x = x >> 4, n += 4;
+	if (x >= 4)
+		x = x >> 2, n += 2;
+	n = n + (x >> 1);
+#else
+	unsigned int c;
+
+	x = (x | 1) >> n;
+	n = n + 15;
+	c = ((x - 0x0100) >> 16) & 8;
+	n = n - c;
+	x = x << c;
+	c = ((x - 0x1000) >> 16) & 4;
+	n = n - c;
+	x = x >> (12 Bit_Sub c);
+	n = n - ((x + 2) >> (x >> 1));
+#endif
+	return n;
+}
+
+#endif
+
+common_inline uintptr_t
+Bit_UpPowerOfTwo(uintptr_t x)
+{
+	if (likely(x > 2)) {
+		x = (uintptr_t) 2 << Bit_FastLog2(x - 1);
+	}
+	return x;
+}
+
+#endif