shl: add flagset helper

A flagset is a dynamic array where each bit of the array can be
independently set/reset. It can be used for minor/major allocations or
for other dynamically growing bitsets.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

diff --git a/src/shl_flagset.h b/src/shl_flagset.h
new file mode 100644 (file)
index 0000000..bc35217
--- /dev/null
+++ b/src/shl_flagset.h
@@ -0,0 +1,135 @@
+/*
+ * shl - Flagset
+ *
+ * Copyright (c) 2013 David Herrmann <dh.herrmann@googlemail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * A dynamic flagset implementation
+ */
+
+#ifndef SHL_FLAGSET_H
+#define SHL_FLAGSET_H
+
+#include <limits.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include "shl_array.h"
+#include "shl_misc.h"
+
+static inline int shl_flagset_new(struct shl_array **out)
+{
+       return shl_array_new(out, sizeof(unsigned long), 1);
+}
+
+static inline void shl_flagset_free(struct shl_array *arr)
+{
+       return shl_array_free(arr);
+}
+
+static inline int shl_flagset_alloc(struct shl_array *arr, unsigned int *out)
+{
+       static const unsigned long one = 1;
+       unsigned int i, j;
+       unsigned long *data;
+       int ret;
+
+       if (!arr)
+               return -EINVAL;
+
+       for (i = 0; i < arr->length; ++i) {
+               data = SHL_ARRAY_AT(arr, unsigned long, i);
+               for (j = 0; j < SHL_ULONG_BITS; ++j) {
+                       if (!(*data & (1UL << j))) {
+                               *data |= 1UL << j;
+                               *out = i * SHL_ULONG_BITS + j;
+                               return 0;
+                       }
+               }
+       }
+
+       ret = shl_array_push(arr, &one);
+       if (ret)
+               return ret;
+
+       *out = (arr->length - 1) * SHL_ULONG_BITS;
+       return 0;
+}
+
+static inline int shl_flagset_reserve(struct shl_array *arr, unsigned int num)
+{
+       int ret;
+       unsigned int idx, off;
+       unsigned long *data;
+
+       if (!arr)
+               return -EINVAL;
+
+       idx = num / SHL_ULONG_BITS;
+       off = num % SHL_ULONG_BITS;
+
+       if (idx >= arr->length) {
+               ret = shl_array_zresize(arr, idx + 1);
+               if (ret)
+                       return ret;
+       }
+
+       data = SHL_ARRAY_AT(arr, unsigned long, idx);
+       if (*data & (1UL << off))
+               return -EEXIST;
+
+       *data |= 1UL << off;
+       return 0;
+}
+
+static inline int shl_flagset_set(struct shl_array *arr, unsigned int num)
+{
+       int ret;
+
+       ret = shl_flagset_reserve(arr, num);
+       if (ret == -EEXIST)
+               return 0;
+
+       return ret;
+}
+
+static inline void shl_flagset_unset(struct shl_array *arr, unsigned int num)
+{
+       unsigned int idx, off;
+       unsigned long *data;
+
+       if (!arr)
+               return;
+
+       idx = num / SHL_ULONG_BITS;
+       off = num % SHL_ULONG_BITS;
+
+       if (idx >= arr->length)
+               return;
+
+       data = SHL_ARRAY_AT(arr, unsigned long, idx);
+       *data &= ~(1UL << off);
+}
+
+#endif /* SHL_FLAGSET_H */

diff --git a/src/shl_misc.h b/src/shl_misc.h
index 2dfa53c..9aa1920 100644 (file)
--- a/src/shl_misc.h
+++ b/src/shl_misc.h
@@ -45,6 +45,7 @@
 #define SHL_EXPORT __attribute__((visibility("default")))
 #define SHL_HAS_BITS(_bitmask, _bits) (((_bitmask) & (_bits)) == (_bits))
 #define SHL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
+#define SHL_ULONG_BITS (sizeof(unsigned long) * 8)
 
 static inline int shl_dirent(const char *path, struct dirent **ent)
 {