From: James Prestwood <prestwoj@gmail.com>
To: ell@lists.linux.dev
Cc: James Prestwood <prestwoj@gmail.com>
Subject: [PATCH 1/2] uintset: add l_uintset_subtract
Date: Fri, 22 Jul 2022 13:27:46 -0700 [thread overview]
Message-ID: <20220722202747.1193490-1-prestwoj@gmail.com> (raw)
This subtracts set_b from set_a, and returns the new set.
---
ell/ell.sym | 1 +
ell/uintset.c | 37 +++++++++++++++++++++++++++++++++++++
ell/uintset.h | 3 +++
3 files changed, 41 insertions(+)
diff --git a/ell/ell.sym b/ell/ell.sym
index 8f4e59d..f454921 100644
--- a/ell/ell.sym
+++ b/ell/ell.sym
@@ -537,6 +537,7 @@ global:
l_uintset_foreach;
l_uintset_clone;
l_uintset_intersect;
+ l_uintset_subtract;
l_uintset_isempty;
l_uintset_size;
/* uuid */
diff --git a/ell/uintset.c b/ell/uintset.c
index 863bc56..4837bcf 100644
--- a/ell/uintset.c
+++ b/ell/uintset.c
@@ -532,6 +532,43 @@ LIB_EXPORT struct l_uintset *l_uintset_intersect(const struct l_uintset *set_a,
return intersection;
}
+/**
+ * l_uintset_subtract:
+ * @set_a: The set of numbers
+ * @set_b: The set of numbers to subtract from set_a
+ *
+ * Subtracts two sets of numbers of an equal base, e.g.:
+ * l_uintset_get_min(set_a) must be equal to l_uintset_get_min(set_b) and
+ * l_uintset_get_max(set_a) must be equal to l_uintset_get_max(set_b)
+ *
+ * Returns: A newly allocated l_uintset containing set_a - set_b
+ */
+LIB_EXPORT struct l_uintset *l_uintset_subtract(const struct l_uintset *set_a,
+ const struct l_uintset *set_b)
+{
+ struct l_uintset *subtraction;
+ uint32_t offset;
+ uint32_t offset_max;
+
+ if (unlikely(!set_a || !set_b))
+ return NULL;
+
+ if (unlikely(set_a->min != set_b->min || set_a->max != set_b->max))
+ return NULL;
+
+ subtraction = l_uintset_new_from_range(set_a->min, set_a->max);
+
+ offset_max = (set_a->size + BITS_PER_LONG - 1) / BITS_PER_LONG;
+
+ /* Subtract by: set_a & ~set_b */
+ for (offset = 0; offset < offset_max; offset++) {
+ subtraction->bits[offset] =
+ set_a->bits[offset] & ~(set_b->bits[offset]);
+ }
+
+ return subtraction;
+}
+
/**
* l_uintset_isempty
* @set: The set of numbers
diff --git a/ell/uintset.h b/ell/uintset.h
index aa9de48..86ce8f7 100644
--- a/ell/uintset.h
+++ b/ell/uintset.h
@@ -60,6 +60,9 @@ void l_uintset_foreach(const struct l_uintset *set,
struct l_uintset *l_uintset_clone(const struct l_uintset *original);
struct l_uintset *l_uintset_intersect(const struct l_uintset *set_a,
const struct l_uintset *set_b);
+struct l_uintset *l_uintset_subtract(const struct l_uintset *set_a,
+ const struct l_uintset *set_b);
+
bool l_uintset_isempty(const struct l_uintset *set);
uint32_t l_uintset_size(const struct l_uintset *set);
--
2.34.1
next reply other threads:[~2022-07-22 20:30 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-22 20:27 James Prestwood [this message]
2022-07-22 20:27 ` [PATCH 2/2] unit: add unit test for l_uintset_subtract James Prestwood
2022-07-22 21:09 ` [PATCH 1/2] uintset: add l_uintset_subtract Denis Kenzior
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