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bitstring(3): Add bitstring traversal macros. 

The macro bit_foreach() traverses all set bits in the bitstring in the
forward direction, assigning each location in turn to variable.

The macro bit_foreach_at() traverses all set bits in the bitstring in
the forward direction at or after the zero-based bit index, assigning
each location in turn to variable.

The bit_foreach_unset() and bit_foreach_unset_at() macros which
traverses unset bits are implemented for completeness.

Reviewed by:	asomers, dougm
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D31469
This commit is contained in:
Vladimir Kondratyev 2021-08-16 23:18:58 +03:00
parent 9b78891df1
commit 14a4d6d013
3 changed files with 268 additions and 1 deletions
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46
share/man/man3/bitstring.3
View File

@ -58,7 +58,7 @@
.\" @(#)bitstring.3 8.1 (Berkeley) 7/19/93
.\" $FreeBSD$
.\"
.Dd November 18, 2019
.Dd August 8, 2021
.Dt BITSTRING 3
.Os
.Sh NAME
@ -106,6 +106,10 @@
.Fn bit_ffc_area_at "bitstr_t *name" "int start" "int nbits" "int size" "int *value"
.Ft void
.Fn bit_ffs_area_at "bitstr_t *name" "int start" "int nbits" "int size" "int *value"
.Fn bit_foreach "bitstr_t *name" "int nbits" "int var"
.Fn bit_foreach_at "bitstr_t *name" "int start" "int nbits" "int var"
.Fn bit_foreach_unset "bitstr_t *name" "int nbits" "int var"
.Fn bit_foreach_unset_at "bitstr_t *name" "int start" "int nbits" "int var"
.Ft void
.Fn bit_nclear "bitstr_t *name" "int start" "int stop"
.Ft void
@ -327,6 +331,46 @@ bits referenced by
at or after the zero-based bit index
.Fa start .
.Pp
The macro
.Fn bit_foreach
traverses all set bits in the array of
.Fa nbits
referenced by
.Fa name
in the forward direction, assigning each location in turn to
.Fa var .
.Pp
The macro
.Fn bit_foreach_at
traverses all set bits in the array of
.Fa nbits
referenced by
.Fa name
in the forward direction at or after the zero-based bit index
.Fa start ,
assigning each location in turn to
.Fa var .
.Pp
The macro
.Fn bit_foreach_unset
traverses all unset bits in the array of
.Fa nbits
referenced by
.Fa name
in the forward direction, assigning each location in turn to
.Fa var .
.Pp
The macro
.Fn bit_foreach_unset_at
traverses all unset bits in the array of
.Fa nbits
referenced by
.Fa name
in the forward direction at or after the zero-based bit index
.Fa start ,
assigning each location in turn to
.Fa var .
.Pp
The arguments in bit string macros are evaluated only once and may safely
have side effects.
.Sh EXAMPLES

16
sys/sys/bitstring.h
View File

@ -419,4 +419,20 @@ out:
*_result = _value;
}
/* Traverse all set bits, assigning each location in turn to iter */
#define bit_foreach_at(_bitstr, _start, _nbits, _iter) \
for (bit_ffs_at((_bitstr), (_start), (_nbits), &(_iter)); \
(_iter) != -1; \
bit_ffs_at((_bitstr), (_iter) + 1, (_nbits), &(_iter)))
#define bit_foreach(_bitstr, _nbits, _iter) \
bit_foreach_at(_bitstr, /*start*/0, _nbits, _iter)
/* Traverse all unset bits, assigning each location in turn to iter */
#define bit_foreach_unset_at(_bitstr, _start, _nbits, _iter) \
for (bit_ffc_at((_bitstr), (_start), (_nbits), &(_iter)); \
(_iter) != -1; \
bit_ffc_at((_bitstr), (_iter) + 1, (_nbits), &(_iter)))
#define bit_foreach_unset(_bitstr, _nbits, _iter) \
bit_foreach_unset_at(_bitstr, /*start*/0, _nbits, _iter)
#endif /* _SYS_BITSTRING_H_ */

207
tests/sys/sys/bitstring_test.c
View File

@ -601,6 +601,209 @@ BITSTRING_TC_DEFINE(bit_count)
}
BITSTRING_TC_DEFINE(bit_foreach)
/* bitstr_t *bitstr, int nbits, const char *memloc */
{
int i, set_bit;
/* Empty bitstr */
memset(bitstr, 0x00, bitstr_size(nbits));
bit_foreach (bitstr, nbits, set_bit) {
atf_tc_fail("bit_foreach_%d_%s_%s: Failed at location %d",
nbits, "clear", memloc, set_bit);
}
/* Full bitstr */
i = 0;
memset(bitstr, 0xFF, bitstr_size(nbits));
bit_foreach(bitstr, nbits, set_bit) {
ATF_REQUIRE_MSG(set_bit == i,
"bit_foreach_%d_%s_%s: Failed on turn %d at location %d",
nbits, "set", memloc, i, set_bit);
i++;
}
ATF_REQUIRE_MSG(i == nbits,
"bit_foreach_%d_%s_%s: Invalid number of turns %d",
nbits, "set", memloc, i);
/* Alternating bitstr, starts with 0 */
i = 0;
memset(bitstr, 0xAA, bitstr_size(nbits));
bit_foreach(bitstr, nbits, set_bit) {
ATF_REQUIRE_MSG(set_bit == i * 2 + 1,
"bit_foreach_%d_%s_%d_%s: "
"Failed on turn %d at location %d",
nbits, "alternating", 0, memloc, i, set_bit);
i++;
}
ATF_REQUIRE_MSG(i == nbits / 2,
"bit_foreach_%d_%s_%d_%s: Invalid number of turns %d",
nbits, "alternating", 0, memloc, i);
/* Alternating bitstr, starts with 1 */
i = 0;
memset(bitstr, 0x55, bitstr_size(nbits));
bit_foreach(bitstr, nbits, set_bit) {
ATF_REQUIRE_MSG(set_bit == i * 2,
"bit_foreach_%d_%s_%d_%s: "
"Failed on turn %d at location %d",
nbits, "alternating", 1, memloc, i, set_bit);
i++;
}
ATF_REQUIRE_MSG(i == (nbits + 1) / 2,
"bit_foreach_%d_%s_%d_%s: Invalid number of turns %d",
nbits, "alternating", 1, memloc, i);
}
BITSTRING_TC_DEFINE(bit_foreach_at)
/* bitstr_t *bitstr, int nbits, const char *memloc */
{
int i, s, e, set_bit;
/* Invalid _start value */
memset(bitstr, 0xFF, bitstr_size(nbits));
bit_foreach_at(bitstr, nbits, nbits, set_bit) {
atf_tc_fail("bit_foreach_at_%d_%s_%s: Failed at location %d",
nbits, "invalid_start", memloc, set_bit);
}
/* Varying start location */
memset(bitstr, 0xAA, bitstr_size(nbits));
for (s = 0; s < nbits; s++) {
i = 0;
bit_foreach_at(bitstr, s, nbits, set_bit) {
ATF_REQUIRE_MSG(set_bit == (i + s / 2) * 2 + 1,
"bit_foreach_at_%d_%s_%d_%s: "
"Failed on turn %d at location %d",
nbits, "vary_start", s, memloc, i, set_bit);
i++;
}
ATF_REQUIRE_MSG(i == nbits / 2 - s / 2,
"bit_foreach_at_%d_%s_%d_%s: Invalid number of turns %d",
nbits, "vary_start", s, memloc, i);
}
/* Varying end location */
memset(bitstr, 0xAA, bitstr_size(nbits));
for (e = 0; e < nbits; e++) {
i = 0;
bit_foreach_at(bitstr, 0, e, set_bit) {
ATF_REQUIRE_MSG(set_bit == i * 2 + 1,
"bit_foreach_at_%d_%s_%d_%s: "
"Failed on turn %d at location %d",
nbits, "vary_end", e, memloc, i, set_bit);
i++;
}
ATF_REQUIRE_MSG(i == e / 2,
"bit_foreach_at_%d_%s_%d_%s: Invalid number of turns %d",
nbits, "vary_end", e, memloc, i);
}
}
BITSTRING_TC_DEFINE(bit_foreach_unset)
/* bitstr_t *bitstr, int nbits, const char *memloc */
{
int i, unset_bit;
/* Empty bitstr */
i = 0;
memset(bitstr, 0, bitstr_size(nbits));
bit_foreach_unset(bitstr, nbits, unset_bit) {
ATF_REQUIRE_MSG(unset_bit == i,
"bit_foreach_unset_%d_%s_%s: "
"Failed on turn %d at location %d",
nbits, "clear", memloc, i, unset_bit);
i++;
}
ATF_REQUIRE_MSG(i == nbits,
"bit_foreach_unset_%d_%s_%s: Invalid number of turns %d",
nbits, "set", memloc, i);
/* Full bitstr */
memset(bitstr, 0xFF, bitstr_size(nbits));
bit_foreach_unset(bitstr, nbits, unset_bit) {
atf_tc_fail("bit_foreach_unset_%d_%s_%s: "
"Failed at location %d",
nbits, "set", memloc, unset_bit);
}
/* Alternating bitstr, starts with 0 */
i = 0;
memset(bitstr, 0xAA, bitstr_size(nbits));
bit_foreach_unset(bitstr, nbits, unset_bit) {
ATF_REQUIRE_MSG(unset_bit == i * 2,
"bit_foreach_unset_%d_%s_%d_%s: "
"Failed on turn %d at location %d",
nbits, "alternating", 0, memloc, i, unset_bit);
i++;
}
ATF_REQUIRE_MSG(i == (nbits + 1) / 2,
"bit_foreach_unset_%d_%s_%d_%s: Invalid number of turns %d",
nbits, "alternating", 0, memloc, i);
/* Alternating bitstr, starts with 1 */
i = 0;
memset(bitstr, 0x55, bitstr_size(nbits));
bit_foreach_unset(bitstr, nbits, unset_bit) {
ATF_REQUIRE_MSG(unset_bit == i * 2 + 1,
"bit_foreach_unset_%d_%s_%d_%s: "
"Failed on turn %d at location %d",
nbits, "alternating", 1, memloc, i, unset_bit);
i++;
}
ATF_REQUIRE_MSG(i == nbits / 2,
"bit_foreach_unset_%d_%s_%d_%s: Invalid number of turns %d",
nbits, "alternating", 1, memloc, i);
}
BITSTRING_TC_DEFINE(bit_foreach_unset_at)
/* bitstr_t *bitstr, int nbits, const char *memloc */
{
int i, s, e, unset_bit;
/* Invalid _start value */
memset(bitstr, 0, bitstr_size(nbits));
bit_foreach_unset_at(bitstr, nbits, nbits, unset_bit) {
atf_tc_fail("bit_foreach_unset_at_%d_%s_%s: "
"Failed at location %d",
nbits, "invalid_start", memloc, unset_bit);
}
/* Varying start location */
memset(bitstr, 0xAA, bitstr_size(nbits));
for (s = 0; s < nbits; s++) {
i = 0;
bit_foreach_unset_at(bitstr, s, nbits, unset_bit) {
ATF_REQUIRE_MSG(unset_bit == (i + (s + 1) / 2) * 2,
"bit_foreach_unset_at_%d_%s_%d_%s: "
"Failed on turn %d at location %d",
nbits, "vary_start", s, memloc, i, unset_bit);
i++;
}
ATF_REQUIRE_MSG(i == (nbits + 1) / 2 - (s + 1) / 2,
"bit_foreach_unset_at_%d_%s_%d_%s: "
"Invalid number of turns %d",
nbits, "vary_start", s, memloc, i);
}
/* Varying end location */
memset(bitstr, 0xAA, bitstr_size(nbits));
for (e = 0; e < nbits; e++) {
i = 0;
bit_foreach_unset_at(bitstr, 0, e, unset_bit) {
ATF_REQUIRE_MSG(unset_bit == i * 2,
"bit_foreach_unset_at_%d_%s_%d_%s: "
"Failed on turn %d at location %d",
nbits, "vary_end", e, memloc, i, unset_bit);
i++;
}
ATF_REQUIRE_MSG(i == (e + 1) / 2,
"bit_foreach_unset_at_%d_%s_%d_%s: "
"Invalid number of turns %d",
nbits, "vary_end", e, memloc, i);
}
}
ATF_TP_ADD_TCS(tp)
{
@ -619,6 +822,10 @@ ATF_TP_ADD_TCS(tp)
BITSTRING_TC_ADD(tp, bit_count);
BITSTRING_TC_ADD(tp, bit_ffs_area_no_match);
BITSTRING_TC_ADD(tp, bit_ffc_area_no_match);
BITSTRING_TC_ADD(tp, bit_foreach);
BITSTRING_TC_ADD(tp, bit_foreach_at);
BITSTRING_TC_ADD(tp, bit_foreach_unset);
BITSTRING_TC_ADD(tp, bit_foreach_unset_at);
return (atf_no_error());
}