Staging: add echo cancelation module

This is used by mISDN and Zaptel drivers.

From: Steve Underwood <steveu@coppice.org>
From: David Rowe <david@rowetel.com>
Cc: Tzafrir Cohen <tzafrir.cohen@xorcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/Kconfig

@@ -39,4 +39,6 @@ source "drivers/staging/winbond/Kconfig"
 
 source "drivers/staging/wlan-ng/Kconfig"
 
+source "drivers/staging/echo/Kconfig"
+
 endif # STAGING

drivers/staging/Makefile

@@ -8,3 +8,4 @@ obj-$(CONFIG_VIDEO_GO7007)	+= go7007/
 obj-$(CONFIG_USB_IP_COMMON)	+= usbip/
 obj-$(CONFIG_W35UND)		+= winbond/
 obj-$(CONFIG_PRISM2_USB)	+= wlan-ng/
+obj-$(CONFIG_ECHO)		+= echo/

drivers/staging/echo/Kconfig

@@ -0,0 +1,9 @@
+config ECHO
+	tristate "Line Echo Canceller support"
+	default n
+	---help---
+	  This driver provides line echo cancelling support for mISDN and
+	  Zaptel drivers.
+
+	  To compile this driver as a module, choose M here. The module
+	  will be called echo.

drivers/staging/echo/Makefile

@@ -0,0 +1 @@
+obj-$(CONFIG_ECHO) += echo.o

drivers/staging/echo/TODO

@@ -0,0 +1,10 @@
+TODO:
+	- checkpatch.pl cleanups
+	- Lindent
+	- typedef removals
+	- handle bit_operations.h (merge in or make part of common code?)
+	- remove proc interface, only use echo.h interface (proc interface is
+	  racy and not correct.)
+
+Please send patches to Greg Kroah-Hartman <greg@kroah.com> and Cc: Steve
+Underwood <steveu@coppice.org> and David Rowe <david@rowetel.com>

drivers/staging/echo/bit_operations.h

@@ -0,0 +1,253 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * bit_operations.h - Various bit level operations, such as bit reversal
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2006 Steve Underwood
+ *
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * $Id: bit_operations.h,v 1.11 2006/11/28 15:37:03 steveu Exp $
+ */
+
+/*! \file */
+
+#if !defined(_BIT_OPERATIONS_H_)
+#define _BIT_OPERATIONS_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#if defined(__i386__)  ||  defined(__x86_64__)
+/*! \brief Find the bit position of the highest set bit in a word
+    \param bits The word to be searched
+    \return The bit number of the highest set bit, or -1 if the word is zero. */
+static __inline__ int top_bit(unsigned int bits)
+{
+    int res;
+
+    __asm__ (" xorl %[res],%[res];\n"
+             " decl %[res];\n"
+             " bsrl %[bits],%[res]\n"
+             : [res] "=&r" (res)
+             : [bits] "rm" (bits));
+    return res;
+}
+/*- End of function --------------------------------------------------------*/
+
+/*! \brief Find the bit position of the lowest set bit in a word
+    \param bits The word to be searched
+    \return The bit number of the lowest set bit, or -1 if the word is zero. */
+static __inline__ int bottom_bit(unsigned int bits)
+{
+    int res;
+
+    __asm__ (" xorl %[res],%[res];\n"
+             " decl %[res];\n"
+             " bsfl %[bits],%[res]\n"
+             : [res] "=&r" (res)
+             : [bits] "rm" (bits));
+    return res;
+}
+/*- End of function --------------------------------------------------------*/
+#else
+static __inline__ int top_bit(unsigned int bits)
+{
+    int i;
+
+    if (bits == 0)
+        return -1;
+    i = 0;
+    if (bits & 0xFFFF0000)
+    {
+        bits &= 0xFFFF0000;
+        i += 16;
+    }
+    if (bits & 0xFF00FF00)
+    {
+        bits &= 0xFF00FF00;
+        i += 8;
+    }
+    if (bits & 0xF0F0F0F0)
+    {
+        bits &= 0xF0F0F0F0;
+        i += 4;
+    }
+    if (bits & 0xCCCCCCCC)
+    {
+        bits &= 0xCCCCCCCC;
+        i += 2;
+    }
+    if (bits & 0xAAAAAAAA)
+    {
+        bits &= 0xAAAAAAAA;
+        i += 1;
+    }
+    return i;
+}
+/*- End of function --------------------------------------------------------*/
+
+static __inline__ int bottom_bit(unsigned int bits)
+{
+    int i;
+
+    if (bits == 0)
+        return -1;
+    i = 32;
+    if (bits & 0x0000FFFF)
+    {
+        bits &= 0x0000FFFF;
+        i -= 16;
+    }
+    if (bits & 0x00FF00FF)
+    {
+        bits &= 0x00FF00FF;
+        i -= 8;
+    }
+    if (bits & 0x0F0F0F0F)
+    {
+        bits &= 0x0F0F0F0F;
+        i -= 4;
+    }
+    if (bits & 0x33333333)
+    {
+        bits &= 0x33333333;
+        i -= 2;
+    }
+    if (bits & 0x55555555)
+    {
+        bits &= 0x55555555;
+        i -= 1;
+    }
+    return i;
+}
+/*- End of function --------------------------------------------------------*/
+#endif
+
+/*! \brief Bit reverse a byte.
+    \param data The byte to be reversed.
+    \return The bit reversed version of data. */
+static __inline__ uint8_t bit_reverse8(uint8_t x)
+{
+#if defined(__i386__)  ||  defined(__x86_64__)
+    /* If multiply is fast */
+    return ((x*0x0802U & 0x22110U) | (x*0x8020U & 0x88440U))*0x10101U >> 16;
+#else
+    /* If multiply is slow, but we have a barrel shifter */
+    x = (x >> 4) | (x << 4);
+    x = ((x & 0xCC) >> 2) | ((x & 0x33) << 2);
+    return ((x & 0xAA) >> 1) | ((x & 0x55) << 1);
+#endif
+}
+/*- End of function --------------------------------------------------------*/
+
+/*! \brief Bit reverse a 16 bit word.
+    \param data The word to be reversed.
+    \return The bit reversed version of data. */
+uint16_t bit_reverse16(uint16_t data);
+
+/*! \brief Bit reverse a 32 bit word.
+    \param data The word to be reversed.
+    \return The bit reversed version of data. */
+uint32_t bit_reverse32(uint32_t data);
+
+/*! \brief Bit reverse each of the four bytes in a 32 bit word.
+    \param data The word to be reversed.
+    \return The bit reversed version of data. */
+uint32_t bit_reverse_4bytes(uint32_t data);
+
+/*! \brief Find the number of set bits in a 32 bit word.
+    \param x The word to be searched.
+    \return The number of set bits. */
+int one_bits32(uint32_t x);
+
+/*! \brief Create a mask as wide as the number in a 32 bit word.
+    \param x The word to be searched.
+    \return The mask. */
+uint32_t make_mask32(uint32_t x);
+
+/*! \brief Create a mask as wide as the number in a 16 bit word.
+    \param x The word to be searched.
+    \return The mask. */
+uint16_t make_mask16(uint16_t x);
+
+/*! \brief Find the least significant one in a word, and return a word
+           with just that bit set.
+    \param x The word to be searched.
+    \return The word with the single set bit. */
+static __inline__ uint32_t least_significant_one32(uint32_t x)
+{
+    return (x & (-(int32_t) x));
+}
+/*- End of function --------------------------------------------------------*/
+
+/*! \brief Find the most significant one in a word, and return a word
+           with just that bit set.
+    \param x The word to be searched.
+    \return The word with the single set bit. */
+static __inline__ uint32_t most_significant_one32(uint32_t x)
+{
+#if defined(__i386__)  ||  defined(__x86_64__)
+    return 1 << top_bit(x);
+#else
+    x = make_mask32(x);
+    return (x ^ (x >> 1));
+#endif
+}
+/*- End of function --------------------------------------------------------*/
+
+/*! \brief Find the parity of a byte.
+    \param x The byte to be checked.
+    \return 1 for odd, or 0 for even. */
+static __inline__ int parity8(uint8_t x)
+{
+    x = (x ^ (x >> 4)) & 0x0F;
+    return (0x6996 >> x) & 1;
+}
+/*- End of function --------------------------------------------------------*/
+
+/*! \brief Find the parity of a 16 bit word.
+    \param x The word to be checked.
+    \return 1 for odd, or 0 for even. */
+static __inline__ int parity16(uint16_t x)
+{
+    x ^= (x >> 8);
+    x = (x ^ (x >> 4)) & 0x0F;
+    return (0x6996 >> x) & 1;
+}
+/*- End of function --------------------------------------------------------*/
+
+/*! \brief Find the parity of a 32 bit word.
+    \param x The word to be checked.
+    \return 1 for odd, or 0 for even. */
+static __inline__ int parity32(uint32_t x)
+{
+    x ^= (x >> 16);
+    x ^= (x >> 8);
+    x = (x ^ (x >> 4)) & 0x0F;
+    return (0x6996 >> x) & 1;
+}
+/*- End of function --------------------------------------------------------*/
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/