util.c

00001 /***************************************************************************//**
00002  *   @file   util.c
00003  *   @brief  Implementation of utility functions.
00004  *   @author DBogdan (dragos.bogdan@analog.com)
00005 ********************************************************************************
00006  * Copyright 2018(c) Analog Devices, Inc.
00007  *
00008  * All rights reserved.
00009  *
00010  * Redistribution and use in source and binary forms, with or without
00011  * modification, are permitted provided that the following conditions are met:
00012  *  - Redistributions of source code must retain the above copyright
00013  *    notice, this list of conditions and the following disclaimer.
00014  *  - Redistributions in binary form must reproduce the above copyright
00015  *    notice, this list of conditions and the following disclaimer in
00016  *    the documentation and/or other materials provided with the
00017  *    distribution.
00018  *  - Neither the name of Analog Devices, Inc. nor the names of its
00019  *    contributors may be used to endorse or promote products derived
00020  *    from this software without specific prior written permission.
00021  *  - The use of this software may or may not infringe the patent rights
00022  *    of one or more patent holders.  This license does not release you
00023  *    from the requirement that you obtain separate licenses from these
00024  *    patent holders to use this software.
00025  *  - Use of the software either in source or binary form, must be run
00026  *    on or directly connected to an Analog Devices Inc. component.
00027  *
00028  * THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR
00029  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT,
00030  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
00031  * IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT,
00032  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
00033  * LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR
00034  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
00035  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
00036  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
00037  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00038 *******************************************************************************/
00039 
00040 /******************************************************************************/
00041 /***************************** Include Files **********************************/
00042 /******************************************************************************/
00043 #include <string.h>
00044 #include <stdlib.h>
00045 #include "platform_drivers.h"
00046 #include "errno.h"
00047 /******************************************************************************/
00048 /************************** Functions Implementation **************************/
00049 /******************************************************************************/
00050 
00051 /**
00052  * Find first set bit in word.
00053  */
00054 uint32_t find_first_set_bit(uint32_t word)
00055 {
00056     uint32_t first_set_bit = 0;
00057 
00058     while (word) {
00059         if (word & 0x1)
00060             return first_set_bit;
00061         word >>= 1;
00062         first_set_bit ++;
00063     }
00064 
00065     return 32;
00066 }
00067 
00068 /**
00069  * Find last set bit in word.
00070  */
00071 uint32_t find_last_set_bit(uint32_t word)
00072 {
00073     uint32_t bit = 0;
00074     uint32_t last_set_bit = 32;
00075 
00076     while (word) {
00077         if (word & 0x1)
00078             last_set_bit = bit;
00079         word >>= 1;
00080         bit ++;
00081     }
00082 
00083     return last_set_bit;
00084 }
00085 
00086 /**
00087  * Locate the closest element in an array.
00088  */
00089 uint32_t find_closest(int32_t val,
00090               const int32_t *array,
00091               uint32_t size)
00092 {
00093     int32_t diff = abs(array[0] - val);
00094     uint32_t ret = 0;
00095     uint32_t i;
00096 
00097     for (i = 1; i < size; i++) {
00098         if (abs(array[i] - val) < diff) {
00099             diff = abs(array[i] - val);
00100             ret = i;
00101         }
00102     }
00103 
00104     return ret;
00105 }
00106 
00107 /**
00108  * Shift the value and apply the specified mask.
00109  */
00110 uint32_t field_prep(uint32_t mask, uint32_t val)
00111 {
00112     return (val << find_first_set_bit(mask)) & mask;
00113 }
00114 
00115 /**
00116  * Get a field specified by a mask from a word.
00117  */
00118 uint32_t field_get(uint32_t mask, uint32_t word)
00119 {
00120     return (word & mask) >> find_first_set_bit(mask);
00121 }
00122 
00123 /**
00124  * Log base 2 of the given number.
00125  */
00126 int32_t log_base_2(uint32_t x)
00127 {
00128     return find_last_set_bit(x);
00129 }
00130 
00131 /**
00132  * Find greatest common divisor of the given two numbers.
00133  */
00134 uint32_t greatest_common_divisor(uint32_t a,
00135                  uint32_t b)
00136 {
00137     uint32_t div;
00138     uint32_t common_div = 1;
00139 
00140     if ((a == 0) || (b == 0))
00141         return max(a, b);
00142 
00143     for (div = 1; (div <= a) && (div <= b); div++)
00144         if (!(a % div) && !(b % div))
00145             common_div = div;
00146 
00147     return common_div;
00148 }
00149 
00150 /**
00151  * Calculate best rational approximation for a given fraction.
00152  */
00153 void rational_best_approximation(uint32_t given_numerator,
00154                  uint32_t given_denominator,
00155                  uint32_t max_numerator,
00156                  uint32_t max_denominator,
00157                  uint32_t *best_numerator,
00158                  uint32_t *best_denominator)
00159 {
00160     uint32_t gcd;
00161 
00162     gcd = greatest_common_divisor(given_numerator, given_denominator);
00163 
00164     *best_numerator = given_numerator / gcd;
00165     *best_denominator = given_denominator / gcd;
00166 
00167     if ((*best_numerator > max_numerator) ||
00168         (*best_denominator > max_denominator)) {
00169         *best_numerator = 0;
00170         *best_denominator = 0;
00171     }
00172 }
00173 
00174 /**
00175  * Calculate the number of set bits.
00176  */
00177 uint32_t hweight8(uint32_t word)
00178 {
00179     uint32_t count = 0;
00180 
00181     while (word) {
00182         if (word & 0x1)
00183             count++;
00184         word >>= 1;
00185     }
00186 
00187     return count;
00188 }
00189 
00190 /**
00191  * Calculate the quotient and the remainder of an integer division.
00192  */
00193 uint64_t do_div(uint64_t* n,
00194         uint64_t base)
00195 {
00196     uint64_t mod = 0;
00197 
00198     mod = *n % base;
00199     *n = *n / base;
00200 
00201     return mod;
00202 }
00203 
00204 /**
00205  * Unsigned 64bit divide with 64bit divisor and remainder
00206  */
00207 uint64_t div64_u64_rem(uint64_t dividend, uint64_t divisor, uint64_t *remainder)
00208 {
00209     *remainder = dividend % divisor;
00210 
00211     return dividend / divisor;
00212 }
00213 
00214 /**
00215  * Unsigned 64bit divide with 32bit divisor with remainder
00216  */
00217 uint64_t div_u64_rem(uint64_t dividend, uint32_t divisor, uint32_t *remainder)
00218 {
00219     *remainder = do_div(&dividend, divisor);
00220 
00221     return dividend;
00222 }
00223 
00224 /**
00225  * Unsigned 64bit divide with 32bit divisor
00226  */
00227 uint64_t div_u64(uint64_t dividend, uint32_t divisor)
00228 {
00229     uint32_t remainder;
00230 
00231     return div_u64_rem(dividend, divisor, &remainder);
00232 }
00233 
00234 /**
00235  * Converts from string to int32_t
00236  * @param *str
00237  * @return int32_t
00238  */
00239 int32_t str_to_int32(const char *str)
00240 {
00241     char *end;
00242     int32_t value = strtol(str, &end, 0);
00243 
00244     if (end == str)
00245         return -EINVAL;
00246     else
00247         return value;
00248 }
00249 
00250 /**
00251  * Converts from string to uint32_t
00252  * @param *str
00253  * @return uint32_t
00254  */
00255 uint32_t srt_to_uint32(const char *str)
00256 {
00257     char *end;
00258     uint32_t value = strtoul(str, &end, 0);
00259 
00260     if (end == str)
00261         return -EINVAL;
00262     else
00263         return value;
00264 }