[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH V3 2/4] xen: Add generic implementation of binary search
This patch adds the generic implementation of binary search algorithm which is copied from Linux kernel v4.7-rc7. No functional changes. Signed-off-by: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Reviewed-by: Julien Grall <julien.grall@xxxxxxx> --- Changes since v2: Fixed the compilation issue due to a missing ';'. Fixed typo. Changes since v1: Removed the header file xen/include/xen/bsearch.h. Defined function bsearch() prototype in the header file xen/lib.h. xen/common/Makefile | 1 + xen/common/bsearch.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ xen/include/xen/lib.h | 3 +++ 3 files changed, 55 insertions(+) create mode 100644 xen/common/bsearch.c diff --git a/xen/common/Makefile b/xen/common/Makefile index dbf00c6..f8123c2 100644 --- a/xen/common/Makefile +++ b/xen/common/Makefile @@ -43,6 +43,7 @@ obj-y += schedule.o obj-y += shutdown.o obj-y += softirq.o obj-y += sort.o +obj-y += bsearch.o obj-y += smp.o obj-y += spinlock.o obj-y += stop_machine.o diff --git a/xen/common/bsearch.c b/xen/common/bsearch.c new file mode 100644 index 0000000..7090930 --- /dev/null +++ b/xen/common/bsearch.c @@ -0,0 +1,51 @@ +/* + * A generic implementation of binary search for the Linux kernel + * + * Copyright (C) 2008-2009 Ksplice, Inc. + * Author: Tim Abbott <tabbott@xxxxxxxxxxx> + * + * 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; version 2. + */ + +#include <xen/lib.h> + +/* + * bsearch - binary search an array of elements + * @key: pointer to item being searched for + * @base: pointer to first element to search + * @num: number of elements + * @size: size of each element + * @cmp: pointer to comparison function + * + * This function does a binary search on the given array. The + * contents of the array should already be in ascending sorted order + * under the provided comparison function. + * + * Note that the key need not have the same type as the elements in + * the array, e.g. key could be a string and the comparison function + * could compare the string with the struct's name field. However, if + * the key and elements in the array are of the same type, you can use + * the same comparison function for both sort() and bsearch(). + */ +void *bsearch(const void *key, const void *base, size_t num, size_t size, + int (*cmp)(const void *key, const void *elt)) +{ + size_t start = 0, end = num; + int result; + + while (start < end) { + size_t mid = start + (end - start) / 2; + + result = cmp(key, base + mid * size); + if (result < 0) + end = mid; + else if (result > 0) + start = mid + 1; + else + return (void *)base + mid * size; + } + + return NULL; +} diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h index b1b0fb2..b90d582 100644 --- a/xen/include/xen/lib.h +++ b/xen/include/xen/lib.h @@ -153,4 +153,7 @@ void dump_execstate(struct cpu_user_regs *); void init_constructors(void); +void *bsearch(const void *key, const void *base, size_t num, size_t size, + int (*cmp)(const void *key, const void *elt)); + #endif /* __LIB_H__ */ -- Qualcomm Datacenter Technologies, Inc. on behalf of the Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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