bitset: Reimplement BIT_FOREACH_IS(SET|CLR)
Eliminate the nested loops and re-implement following a suggestion from rlibby. Add some simple regression tests. Reviewed by: rlibby, kib MFC after: 2 weeks Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D32472
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@ -357,6 +357,10 @@ Similarly,
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.Fn BIT_FOREACH_ISCLR
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iterates over all clear bits in
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.Fa bitset .
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In the loop body, the currently indexed bit may be set or cleared.
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However, setting or clearing bits other than the currently indexed
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bit does not guarantee that they will or will not be returned in
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subsequent iterations of the same loop.
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.Pp
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The
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.Fn BIT_COUNT
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@ -271,12 +271,31 @@
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__count; \
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})
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/* Non-destructively loop over all set or clear bits in the set. */
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#define _BIT_FOREACH_ADVANCE(_s, i, p, op) __extension__ ({ \
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int __found; \
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for (;;) { \
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if (__bits != 0) { \
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int __bit = ffsl(__bits) - 1; \
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__bits &= ~(1ul << __bit); \
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(i) = __i * _BITSET_BITS + __bit; \
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__found = 1; \
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break; \
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} \
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if (++__i == __bitset_words(_s)) { \
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__found = 0; \
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break; \
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} \
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__bits = op((p)->__bits[__i]); \
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} \
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__found != 0; \
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})
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/*
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* Non-destructively loop over all set or clear bits in the set.
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*/
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#define _BIT_FOREACH(_s, i, p, op) \
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for (__size_t __i = 0; __i < __bitset_words(_s); __i++) \
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for (long __j = op((p)->__bits[__i]), __b = ffsl(__j); \
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(i = (__b - 1) + __i * _BITSET_BITS), __j != 0; \
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__j &= ~(1l << i), __b = ffsl(__j))
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for (long __i = -1, __bits = 0; \
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_BIT_FOREACH_ADVANCE(_s, i, p, op); )
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#define BIT_FOREACH_ISSET(_s, i, p) _BIT_FOREACH(_s, i, p, )
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#define BIT_FOREACH_ISCLR(_s, i, p) _BIT_FOREACH(_s, i, p, ~)
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@ -4,7 +4,12 @@
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TESTSDIR= ${TESTSBASE}/sys/sys
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ATF_TESTS_C= arb_test bitstring_test qmath_test rb_test splay_test
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ATF_TESTS_C= arb_test \
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bitset_test \
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bitstring_test \
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qmath_test \
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rb_test \
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splay_test
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.if ${COMPILER_TYPE} == "gcc"
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CFLAGS.bitstring_test= -fno-strict-overflow
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88
tests/sys/sys/bitset_test.c
Normal file
88
tests/sys/sys/bitset_test.c
Normal file
@ -0,0 +1,88 @@
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/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2021 The FreeBSD Foundation
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*
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* This software was developed by Mark Johnston under sponsorship from
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* the FreeBSD Foundation.
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*/
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#include <sys/types.h>
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#include <sys/_bitset.h>
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#include <sys/bitset.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <atf-c.h>
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BITSET_DEFINE(bs256, 256);
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ATF_TC_WITHOUT_HEAD(bit_foreach);
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ATF_TC_BODY(bit_foreach, tc)
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{
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struct bs256 bs0, bs1, bsrand;
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int setc, clrc, i;
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#define _BIT_FOREACH_COUNT(s, bs) do { \
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int prev = -1; \
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setc = clrc = 0; \
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BIT_FOREACH_ISSET((s), i, (bs)) { \
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ATF_REQUIRE_MSG(prev < i, "incorrect bit ordering"); \
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ATF_REQUIRE_MSG(BIT_ISSET((s), i, (bs)), \
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"bit %d is not set", i); \
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setc++; \
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prev = i; \
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} \
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prev = -1; \
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BIT_FOREACH_ISCLR((s), i, (bs)) { \
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ATF_REQUIRE_MSG(prev < i, "incorrect bit ordering"); \
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ATF_REQUIRE_MSG(!BIT_ISSET((s), i, (bs)), \
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"bit %d is set", i); \
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clrc++; \
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prev = i; \
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} \
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} while (0)
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/*
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* Create several bitsets, and for each one count the number
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* of set and clear bits and make sure they match what we expect.
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*/
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BIT_FILL(256, &bs1);
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_BIT_FOREACH_COUNT(256, &bs1);
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ATF_REQUIRE_MSG(setc == 256, "incorrect set count %d", setc);
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ATF_REQUIRE_MSG(clrc == 0, "incorrect clear count %d", clrc);
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BIT_ZERO(256, &bs0);
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_BIT_FOREACH_COUNT(256, &bs0);
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ATF_REQUIRE_MSG(setc == 0, "incorrect set count %d", setc);
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ATF_REQUIRE_MSG(clrc == 256, "incorrect clear count %d", clrc);
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BIT_ZERO(256, &bsrand);
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for (i = 0; i < 256; i++)
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if (random() % 2 != 0)
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BIT_SET(256, i, &bsrand);
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_BIT_FOREACH_COUNT(256, &bsrand);
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ATF_REQUIRE_MSG(setc + clrc == 256, "incorrect counts %d, %d",
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setc, clrc);
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/*
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* Try to verify that we can safely clear bits in the set while
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* iterating.
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*/
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BIT_FOREACH_ISSET(256, i, &bsrand) {
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ATF_REQUIRE(setc-- > 0);
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BIT_CLR(256, i, &bsrand);
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}
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_BIT_FOREACH_COUNT(256, &bsrand);
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ATF_REQUIRE_MSG(setc == 0, "incorrect set count %d", setc);
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ATF_REQUIRE_MSG(clrc == 256, "incorrect clear count %d", clrc);
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#undef _BIT_FOREACH_COUNT
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}
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ATF_TP_ADD_TCS(tp)
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{
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ATF_TP_ADD_TC(tp, bit_foreach);
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return (atf_no_error());
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}
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