From 7150962d637cf38617924f7f72ea00612283eb89 Mon Sep 17 00:00:00 2001 From: Arend van Spriel Date: Tue, 31 May 2011 11:22:15 +0200 Subject: lib: crc8: add new library module providing crc8 algorithm The brcm80211 driver in staging tree uses a crc8 function. Based on feedback from John Linville to move this to lib directory, the linux source has been searched. Although there is currently only one other kernel driver using this algorithm (ie. drivers/ssb) we are providing this as a library function for others to use. Cc: linux-kernel@vger.kernel.org Cc: linux-wireless@vger.kernel.org Cc: Dan Carpenter Cc: George Spelvin Cc: Randy Dunlap Reviewed-by: Henry Ptasinski Reviewed-by: Roland Vossen Reviewed-by: "Franky (Zhenhui) Lin" Signed-off-by: Arend van Spriel Signed-off-by: John W. Linville --- lib/Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'lib/Makefile') diff --git a/lib/Makefile b/lib/Makefile index 4b49a249064b..704959d2018b 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -65,6 +65,7 @@ obj-$(CONFIG_CRC_ITU_T) += crc-itu-t.o obj-$(CONFIG_CRC32) += crc32.o obj-$(CONFIG_CRC7) += crc7.o obj-$(CONFIG_LIBCRC32C) += libcrc32c.o +obj-$(CONFIG_CRC8) += crc8.o obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o obj-$(CONFIG_ZLIB_INFLATE) += zlib_inflate/ -- cgit v1.2.3-59-g8ed1b From 10f8113ecb76eea72f96c7cfb72d7fed7c282565 Mon Sep 17 00:00:00 2001 From: Arend van Spriel Date: Tue, 31 May 2011 11:22:16 +0200 Subject: lib: cordic: add library module providing cordic angle calculation The brcm80211 driver in the staging tree has a cordic function to determine cosine and sine for a given angle. Feedback received from John Linville suggested that these kind of functions should be made available to others as a library function in the kernel tree. The b43 driver also has a cordic angle calculation implemented. Cc: linux-kernel@vger.kernel.org Cc: linux-wireless@vger.kernel.org Cc: "John W. Linville" Cc: Greg Kroah-Hartman Cc: Dan Carpenter Cc: Randy Dunlap Cc: Larry Finger Reviewed-by: Roland Vossen Reviewed-by: Henry Ptasinski Reviewed-by: Franky (Zhenhui) Lin Signed-off-by: Arend van Spriel Signed-off-by: John W. Linville --- include/linux/cordic.h | 48 +++++++++++++++++++++++ lib/Kconfig | 7 ++++ lib/Makefile | 2 + lib/cordic.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 158 insertions(+) create mode 100644 include/linux/cordic.h create mode 100644 lib/cordic.c (limited to 'lib/Makefile') diff --git a/include/linux/cordic.h b/include/linux/cordic.h new file mode 100644 index 000000000000..f932093e20c2 --- /dev/null +++ b/include/linux/cordic.h @@ -0,0 +1,48 @@ +/* + * Copyright (c) 2011 Broadcom Corporation + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY + * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION + * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN + * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ +#ifndef __CORDIC_H_ +#define __CORDIC_H_ + +#include + +/** + * struct cordic_iq - i/q coordinate. + * + * @i: real part of coordinate (in phase). + * @q: imaginary part of coordinate (quadrature). + */ +struct cordic_iq { + s32 i; + s32 q; +}; + +/** + * cordic_calc_iq() - calculates the i/q coordinate for given angle. + * + * @theta: angle in degrees for which i/q coordinate is to be calculated. + * @coord: function output parameter holding the i/q coordinate. + * + * The function calculates the i/q coordinate for a given angle using + * cordic algorithm. The coordinate consists of a real (i) and an + * imaginary (q) part. The real part is essentially the cosine of the + * angle and the imaginary part is the sine of the angle. The returned + * values are scaled by 2^16 for precision. The range for theta is + * for -180 degrees to +180 degrees. Passed values outside this range are + * converted before doing the actual calculation. + */ +struct cordic_iq cordic_calc_iq(s32 theta); + +#endif /* __CORDIC_H_ */ diff --git a/lib/Kconfig b/lib/Kconfig index ff9e5a34be76..5c702047c57f 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -279,4 +279,11 @@ config AVERAGE If unsure, say N. +config CORDIC + tristate "Cordic function" + help + The option provides arithmetic function using cordic algorithm + so its calculations are in fixed point. Modules can select this + when they require this function. Module will be called cordic. + endmenu diff --git a/lib/Makefile b/lib/Makefile index 704959d2018b..9e3c1b0652d1 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -117,6 +117,8 @@ obj-$(CONFIG_AVERAGE) += average.o obj-$(CONFIG_CPU_RMAP) += cpu_rmap.o +obj-$(CONFIG_CORDIC) += cordic.o + hostprogs-y := gen_crc32table clean-files := crc32table.h diff --git a/lib/cordic.c b/lib/cordic.c new file mode 100644 index 000000000000..aa27a88d7e04 --- /dev/null +++ b/lib/cordic.c @@ -0,0 +1,101 @@ +/* + * Copyright (c) 2011 Broadcom Corporation + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY + * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION + * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN + * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ +#include +#include + +#define CORDIC_ANGLE_GEN 39797 +#define CORDIC_PRECISION_SHIFT 16 +#define CORDIC_NUM_ITER (CORDIC_PRECISION_SHIFT + 2) + +#define FIXED(X) ((s32)((X) << CORDIC_PRECISION_SHIFT)) +#define FLOAT(X) (((X) >= 0) \ + ? ((((X) >> (CORDIC_PRECISION_SHIFT - 1)) + 1) >> 1) \ + : -((((-(X)) >> (CORDIC_PRECISION_SHIFT - 1)) + 1) >> 1)) + +static const s32 arctan_table[] = { + 2949120, + 1740967, + 919879, + 466945, + 234379, + 117304, + 58666, + 29335, + 14668, + 7334, + 3667, + 1833, + 917, + 458, + 229, + 115, + 57, + 29 +}; + +/* + * cordic_calc_iq() - calculates the i/q coordinate for given angle + * + * theta: angle in degrees for which i/q coordinate is to be calculated + * coord: function output parameter holding the i/q coordinate + */ +struct cordic_iq cordic_calc_iq(s32 theta) +{ + struct cordic_iq coord; + s32 angle, valtmp; + unsigned iter; + int signx = 1; + int signtheta; + + coord.i = CORDIC_ANGLE_GEN; + coord.q = 0; + angle = 0; + + theta = FIXED(theta); + signtheta = (theta < 0) ? -1 : 1; + theta = ((theta + FIXED(180) * signtheta) % FIXED(360)) - + FIXED(180) * signtheta; + + if (FLOAT(theta) > 90) { + theta -= FIXED(180); + signx = -1; + } else if (FLOAT(theta) < -90) { + theta += FIXED(180); + signx = -1; + } + + for (iter = 0; iter < CORDIC_NUM_ITER; iter++) { + if (theta > angle) { + valtmp = coord.i - (coord.q >> iter); + coord.q += (coord.i >> iter); + angle += arctan_table[iter]; + } else { + valtmp = coord.i + (coord.q >> iter); + coord.q -= (coord.i >> iter); + angle -= arctan_table[iter]; + } + coord.i = valtmp; + } + + coord.i *= signx; + coord.q *= signx; + return coord; +} +EXPORT_SYMBOL(cordic_calc_iq); + +MODULE_DESCRIPTION("Cordic functions"); +MODULE_AUTHOR("Broadcom Corporation"); +MODULE_LICENSE("Dual BSD/GPL"); -- cgit v1.2.3-59-g8ed1b