Improve performance and functionality of the bitstring(3) api

Two new functions are provided, bit_ffs_at() and bit_ffc_at(), which allow
for efficient searching of set or cleared bits starting from any bit offset
within the bit string.

Performance is improved by operating on longs instead of bytes and using
ffsl() for searches within a long. ffsl() is a compiler builtin in both
clang and gcc for most architectures, converting what was a brute force
while loop search into a couple of instructions.

All of the bitstring(3) API continues to be contained in the header file.
Some of the functions are large enough that perhaps they should be uninlined
and moved to a library, but that is beyond the scope of this commit.

sys/sys/bitstring.h:
        Convert the majority of the existing bit string implementation from
        macros to inline functions.

        Properly protect the implementation from inadvertant macro expansion
        when included in a user's program by prefixing all private
        macros/functions and local variables with '_'.

        Add bit_ffs_at() and bit_ffc_at(). Implement bit_ffs() and
        bit_ffc() in terms of their "at" counterparts.

        Provide a kernel implementation of bit_alloc(), making the full API
        usable in the kernel.

        Improve code documenation.

share/man/man3/bitstring.3:
        Add pre-exisiting API bit_ffc() to the synopsis.

        Document new APIs.

        Document the initialization state of the bit strings
        allocated/declared by bit_alloc() and bit_decl().

        Correct documentation for bitstr_size(). The original code comments
        indicate the size is in bytes, not "elements of bitstr_t". The new
        implementation follows this lead. Only hastd assumed "elements"
        rather than bytes and it has been corrected.

etc/mtree/BSD.tests.dist:
tests/sys/Makefile:
tests/sys/sys/Makefile:
tests/sys/sys/bitstring.c:
        Add tests for all existing and new functionality.

include/bitstring.h
	Include all headers needed by sys/bitstring.h

lib/libbluetooth/bluetooth.h:
usr.sbin/bluetooth/hccontrol/le.c:
        Include bitstring.h instead of sys/bitstring.h.

sbin/hastd/activemap.c:
        Correct usage of bitstr_size().

sys/dev/xen/blkback/blkback.c
        Use new bit_alloc.

sys/kern/subr_unit.c:
        Remove hard-coded assumption that sizeof(bitstr_t) is 1.  Get rid of
        unrb.busy, which caches the number of bits set in unrb.map.  When
        INVARIANTS are disabled, nothing needs to know that information.
        callapse_unr can be adapted to use bit_ffs and bit_ffc instead.
        Eliminating unrb.busy saves memory, simplifies the code, and
        provides a slight speedup when INVARIANTS are disabled.

sys/net/flowtable.c:
        Use the new kernel implementation of bit-alloc, instead of hacking
        the old libc-dependent macro.

sys/sys/param.h
        Update __FreeBSD_version to indicate availability of new API

Submitted by:   gibbs, asomers
Reviewed by:    gibbs, ngie
MFC after:      4 weeks
Sponsored by:   Spectra Logic Corp
Differential Revision:  https://reviews.freebsd.org/D6004

3 files changed, 373 insertions, 0 deletions

diff --git a/tests/sys/Makefile b/tests/sys/Makefile
index 40a5e64..1d488bf 100644
--- a/tests/sys/Makefile
+++ b/tests/sys/Makefile
@@ -19,6 +19,7 @@ TESTS_SUBDIRS+=		mqueue
 TESTS_SUBDIRS+=		netinet
 TESTS_SUBDIRS+=		opencrypto
 TESTS_SUBDIRS+=		posixshm
+TESTS_SUBDIRS+=		sys
 TESTS_SUBDIRS+=		vfs
 TESTS_SUBDIRS+=		vm
 
diff --git a/tests/sys/sys/Makefile b/tests/sys/sys/Makefile
new file mode 100644
index 0000000..eee6d73
--- /dev/null
+++ b/tests/sys/sys/Makefile
@@ -0,0 +1,13 @@
+# $FreeBSD$
+
+PACKAGE=	tests
+FILESGROUPS=	TESTS
+TESTSPACKAGE=	${PACKAGE}
+
+TESTSDIR=	${TESTSBASE}/sys/sys
+
+ATF_TESTS_C=	bitstring_test
+
+WARNS?=	5
+
+.include <bsd.test.mk>
diff --git a/tests/sys/sys/bitstring_test.c b/tests/sys/sys/bitstring_test.c
new file mode 100644
index 0000000..d096552
--- /dev/null
+++ b/tests/sys/sys/bitstring_test.c
@@ -0,0 +1,359 @@
+/*-
+ * Copyright (c) 2014 Spectra Logic Corporation
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions, and the following disclaimer,
+ *    without modification.
+ * 2. Redistributions in binary form must reproduce at minimum a disclaimer
+ *    substantially similar to the "NO WARRANTY" disclaimer below
+ *    ("Disclaimer") and any redistribution must be conditioned upon
+ *    including a substantially similar Disclaimer requirement for further
+ *    binary redistribution.
+ *
+ * NO WARRANTY
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGES.
+ *
+ * $FreeBSD$
+ */
+#include <sys/param.h>
+
+#include <bitstring.h>
+#include <stdio.h>
+
+#include <atf-c.h>
+
+typedef void (testfunc_t)(bitstr_t *bstr, int nbits, const char *memloc);
+
+static void
+bitstring_run_stack_test(testfunc_t *test, int nbits)
+{
+	bitstr_t bit_decl(bitstr, nbits);
+
+	test(bitstr, nbits, "stack");
+}
+
+static void
+bitstring_run_heap_test(testfunc_t *test, int nbits)
+{
+	bitstr_t *bitstr = bit_alloc(nbits);
+
+	test(bitstr, nbits, "heap");
+}
+
+static void
+bitstring_test_runner(testfunc_t *test)
+{
+	const int bitstr_sizes[] = {
+		0,
+		1,
+		_BITSTR_BITS - 1,
+		_BITSTR_BITS,
+		_BITSTR_BITS + 1,
+		2 * _BITSTR_BITS - 1,
+		2 * _BITSTR_BITS,
+		1023,
+		1024
+	};
+
+	for (unsigned long i = 0; i < nitems(bitstr_sizes); i++) {
+		bitstring_run_stack_test(test, bitstr_sizes[i]);
+		bitstring_run_heap_test(test, bitstr_sizes[i]);
+	}
+}
+
+#define	BITSTRING_TC_DEFINE(name)				\
+ATF_TC_WITHOUT_HEAD(name);					\
+static testfunc_t name ## _test;				\
+								\
+ATF_TC_BODY(name, tc)						\
+{								\
+	bitstring_test_runner(name ## _test);			\
+}								\
+								\
+static void							\
+name ## _test(bitstr_t *bitstr, int nbits, const char *memloc)
+
+#define	BITSTRING_TC_ADD(tp, name)				\
+do {								\
+	ATF_TP_ADD_TC(tp, name);				\
+} while (0)
+
+ATF_TC_WITHOUT_HEAD(bitstr_in_struct);
+ATF_TC_BODY(bitstr_in_struct, tc)
+{
+	struct bitstr_containing_struct {
+		bitstr_t bit_decl(bitstr, 8);
+	} test_struct;
+
+	bit_nclear(test_struct.bitstr, 0, 8);
+}
+
+BITSTRING_TC_DEFINE(bit_set)
+/* bitstr_t *bitstr, int nbits, const char *memloc */
+{
+	memset(bitstr, 0, bitstr_size(nbits));
+	
+	for (int i = 0; i < nbits; i++) {
+		bit_set(bitstr, i);
+
+		for (int j = 0; j < nbits; j++) {
+			ATF_REQUIRE_MSG(bit_test(bitstr, j) == (j == i) ? 1 : 0,
+			    "bit_set_%d_%s: Failed on bit %d",
+			    nbits, memloc, i);
+		}
+
+		bit_clear(bitstr, i);
+	}
+}
+
+BITSTRING_TC_DEFINE(bit_clear)
+/* bitstr_t *bitstr, int nbits, const char *memloc */
+{
+	int i, j;
+
+	memset(bitstr, 0xFF, bitstr_size(nbits));
+	for (i = 0; i < nbits; i++) {
+		bit_clear(bitstr, i);
+
+		for (j = 0; j < nbits; j++) {
+			ATF_REQUIRE_MSG(bit_test(bitstr, j) == (j == i) ? 0 : 1,
+			    "bit_clear_%d_%s: Failed on bit %d",
+			    nbits, memloc, i);
+		}
+
+		bit_set(bitstr, i);
+	}
+}
+
+BITSTRING_TC_DEFINE(bit_ffs)
+/* bitstr_t *bitstr, int nbits, const char *memloc */
+{
+	int i;
+	int found_set_bit;
+
+	memset(bitstr, 0, bitstr_size(nbits));
+	bit_ffs(bitstr, nbits, &found_set_bit);
+	ATF_REQUIRE_MSG(found_set_bit == -1,
+	    "bit_ffs_%d_%s: Failed all clear bits.", nbits, memloc);
+
+	for (i = 0; i < nbits; i++) {
+		memset(bitstr, 0xFF, bitstr_size(nbits));
+		if (i > 0)
+			bit_nclear(bitstr, 0, i - 1);
+
+		bit_ffs(bitstr, nbits, &found_set_bit);
+		ATF_REQUIRE_MSG(found_set_bit == i,
+		    "bit_ffs_%d_%s: Failed on bit %d, Result %d",
+		    nbits, memloc, i, found_set_bit);
+	}
+}
+
+BITSTRING_TC_DEFINE(bit_ffc)
+/* bitstr_t *bitstr, int nbits, const char *memloc */
+{
+	int i;
+	int found_clear_bit;
+
+	memset(bitstr, 0xFF, bitstr_size(nbits));
+	bit_ffc(bitstr, nbits, &found_clear_bit);
+	ATF_REQUIRE_MSG(found_clear_bit == -1,
+	    "bit_ffc_%d_%s: Failed all set bits.", nbits, memloc);
+
+	for (i = 0; i < nbits; i++) {
+		memset(bitstr, 0, bitstr_size(nbits));
+		if (i > 0)
+			bit_nset(bitstr, 0, i - 1);
+
+		bit_ffc(bitstr, nbits, &found_clear_bit);
+		ATF_REQUIRE_MSG(found_clear_bit == i,
+		    "bit_ffc_%d_%s: Failed on bit %d, Result %d",
+		    nbits, memloc, i, found_clear_bit);
+	}
+}
+
+BITSTRING_TC_DEFINE(bit_ffs_at)
+/* bitstr_t *bitstr, int nbits, const char *memloc */
+{
+	int i;
+	int found_set_bit;
+
+	memset(bitstr, 0xFF, bitstr_size(nbits));
+	for (i = 0; i < nbits; i++) {
+		bit_ffs_at(bitstr, i, nbits, &found_set_bit);
+		ATF_REQUIRE_MSG(found_set_bit == i,
+		    "bit_ffs_at_%d_%s: Failed on bit %d, Result %d",
+		    nbits, memloc, i, found_set_bit);
+	}
+
+	memset(bitstr, 0, bitstr_size(nbits));
+	for (i = 0; i < nbits; i++) {
+		bit_ffs_at(bitstr, i, nbits, &found_set_bit);
+		ATF_REQUIRE_MSG(found_set_bit == -1,
+		    "bit_ffs_at_%d_%s: Failed on bit %d, Result %d",
+		    nbits, memloc, i, found_set_bit);
+	}
+
+	memset(bitstr, 0x55, bitstr_size(nbits));
+	for (i = 0; i < nbits; i++) {
+		bit_ffs_at(bitstr, i, nbits, &found_set_bit);
+		if (i == nbits - 1 && (nbits & 1) == 0) {
+			ATF_REQUIRE_MSG(found_set_bit == -1,
+			    "bit_ffs_at_%d_%s: Failed on bit %d, Result %d",
+			    nbits, memloc, i, found_set_bit);
+		} else {
+			ATF_REQUIRE_MSG(found_set_bit == i + (i & 1),
+			    "bit_ffs_at_%d_%s: Failed on bit %d, Result %d",
+			    nbits, memloc, i, found_set_bit);
+		}
+	}
+
+	memset(bitstr, 0xAA, bitstr_size(nbits));
+	for (i = 0; i < nbits; i++) {
+		bit_ffs_at(bitstr, i, nbits, &found_set_bit);
+		if (i == nbits - 1 && (nbits & 1) != 0) {
+			ATF_REQUIRE_MSG(found_set_bit == -1,
+			    "bit_ffs_at_%d_%s: Failed on bit %d, Result %d",
+			    nbits, memloc, i, found_set_bit);
+		} else {
+			ATF_REQUIRE_MSG(
+			    found_set_bit == i + ((i & 1) ? 0 : 1),
+			    "bit_ffs_at_%d_%s: Failed on bit %d, Result %d",
+			    nbits, memloc, i, found_set_bit);
+		}
+	}
+}
+
+BITSTRING_TC_DEFINE(bit_ffc_at)
+/* bitstr_t *bitstr, int nbits, const char *memloc */
+{
+	int i, found_clear_bit;
+
+	memset(bitstr, 0, bitstr_size(nbits));
+	for (i = 0; i < nbits; i++) {
+		bit_ffc_at(bitstr, i, nbits, &found_clear_bit);
+		ATF_REQUIRE_MSG(found_clear_bit == i,
+		    "bit_ffc_at_%d_%s: Failed on bit %d, Result %d",
+		    nbits, memloc, i, found_clear_bit);
+	}
+
+	memset(bitstr, 0xFF, bitstr_size(nbits));
+	for (i = 0; i < nbits; i++) {
+		bit_ffc_at(bitstr, i, nbits, &found_clear_bit);
+		ATF_REQUIRE_MSG(found_clear_bit == -1,
+		    "bit_ffc_at_%d_%s: Failed on bit %d, Result %d",
+		    nbits, memloc, i, found_clear_bit);
+	}
+
+	memset(bitstr, 0x55, bitstr_size(nbits));
+	for (i = 0; i < nbits; i++) {
+		bit_ffc_at(bitstr, i, nbits, &found_clear_bit);
+		if (i == nbits - 1 && (nbits & 1) != 0) {
+			ATF_REQUIRE_MSG(found_clear_bit == -1,
+			    "bit_ffc_at_%d_%s: Failed on bit %d, Result %d",
+			    nbits, memloc, i, found_clear_bit);
+		} else {
+			ATF_REQUIRE_MSG(
+			    found_clear_bit == i + ((i & 1) ? 0 : 1),
+			    "bit_ffc_at_%d_%s: Failed on bit %d, Result %d",
+			    nbits, memloc, i, found_clear_bit);
+		}
+	}
+
+	memset(bitstr, 0xAA, bitstr_size(nbits));
+	for (i = 0; i < nbits; i++) {
+		bit_ffc_at(bitstr, i, nbits, &found_clear_bit);
+		if (i == nbits - 1 && (nbits & 1) == 0) {
+			ATF_REQUIRE_MSG(found_clear_bit == -1,
+			    "bit_ffc_at_%d_%s: Failed on bit %d, Result %d",
+			    nbits, memloc, i, found_clear_bit);
+		} else {
+			ATF_REQUIRE_MSG(found_clear_bit == i + (i & 1),
+			    "bit_ffc_at_%d_%s: Failed on bit %d, Result %d",
+			    nbits, memloc, i, found_clear_bit);
+		}
+	}
+}
+
+BITSTRING_TC_DEFINE(bit_nclear)
+/* bitstr_t *bitstr, int nbits, const char *memloc */
+{
+	int i, j;
+	int found_set_bit;
+	int found_clear_bit;
+
+	for (i = 0; i < nbits; i++) {
+		for (j = i; j < nbits; j++) {
+			memset(bitstr, 0xFF, bitstr_size(nbits));
+			bit_nclear(bitstr, i, j);
+
+			bit_ffc(bitstr, nbits, &found_clear_bit);
+			ATF_REQUIRE_MSG(
+			    found_clear_bit == i,
+			    "bit_nclear_%d_%d_%d%s: Failed with result %d",
+			    nbits, i, j, memloc, found_clear_bit);
+
+			bit_ffs_at(bitstr, i, nbits, &found_set_bit);
+			ATF_REQUIRE_MSG(
+			    (j + 1 < nbits) ? found_set_bit == j + 1 : -1,
+			    "bit_nset_%d_%d_%d%s: Failed with result %d",
+			    nbits, i, j, memloc, found_set_bit);
+		}
+	}
+}
+
+BITSTRING_TC_DEFINE(bit_nset)
+/* bitstr_t *bitstr, int nbits, const char *memloc */
+{
+	int i, j;
+	int found_set_bit;
+	int found_clear_bit;
+
+	for (i = 0; i < nbits; i++) {
+		for (j = i; j < nbits; j++) {
+			memset(bitstr, 0, bitstr_size(nbits));
+			bit_nset(bitstr, i, j);
+
+			bit_ffs(bitstr, nbits, &found_set_bit);
+			ATF_REQUIRE_MSG(
+			    found_set_bit == i,
+			    "bit_nset_%d_%d_%d%s: Failed with result %d",
+			    nbits, i, j, memloc, found_set_bit);
+
+			bit_ffc_at(bitstr, i, nbits, &found_clear_bit);
+			ATF_REQUIRE_MSG(
+			    (j + 1 < nbits) ? found_clear_bit == j + 1 : -1,
+			    "bit_nset_%d_%d_%d%s: Failed with result %d",
+			    nbits, i, j, memloc, found_clear_bit);
+		}
+	}
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+
+	ATF_TP_ADD_TC(tp, bitstr_in_struct);
+	BITSTRING_TC_ADD(tp, bit_set);
+	BITSTRING_TC_ADD(tp, bit_clear);
+	BITSTRING_TC_ADD(tp, bit_ffs);
+	BITSTRING_TC_ADD(tp, bit_ffc);
+	BITSTRING_TC_ADD(tp, bit_ffs_at);
+	BITSTRING_TC_ADD(tp, bit_ffc_at);
+	BITSTRING_TC_ADD(tp, bit_nclear);
+	BITSTRING_TC_ADD(tp, bit_nset);
+
+	return (atf_no_error());
+}