From: Matthias Kruk <m@m10k.eu>
Date: Sun, 2 May 2021 00:48:18 +0000 (+0900)
Subject: array: Add dynamic array type
X-Git-Url: https://git.corax.cc/?a=commitdiff_plain;h=9e902569007c4680a5f082fc9f73e15af3244627;p=mwm

array: Add dynamic array type

For storage of monitors, a data type is needed that automatically
grows and shrinks as needed.
This commit adds a dynamic array implementation.
---

diff --git a/array.c b/array.c
new file mode 100644
index 0000000..3a143de
--- /dev/null
+++ b/array.c
@@ -0,0 +1,238 @@
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include "array.h"
+
+#define ARRAY_GROW_SIZE   8
+#define ARRAY_SHRINK_SIZE 8
+
+struct array {
+        int size;
+	void **data;
+	char *flags;
+};
+
+static int _array_grow(struct array *array)
+{
+	int new_size;
+	void **new_data;
+	char *new_flags;
+
+	if(!array) {
+		return(-EINVAL);
+	}
+
+	new_size = array->size + ARRAY_GROW_SIZE;
+	new_data = malloc(sizeof(*array->data) * new_size);
+
+	if(!new_data) {
+		return(-ENOMEM);
+	}
+
+	new_flags = malloc(sizeof(*array->flags) * new_size);
+
+	if(!new_flags) {
+		free(new_data);
+		return(-ENOMEM);
+	}
+
+	if(array->data) {
+		memcpy(new_data, array->data,
+		       array->size * sizeof(*new_data));
+		free(array->data);
+	}
+	memset(new_data + array->size, 0,
+	       ARRAY_GROW_SIZE * sizeof(*new_data));
+
+	if(array->flags) {
+		memcpy(new_flags, array->flags,
+		       array->size * sizeof(*new_flags));
+		free(array->flags);
+	}
+	memset(new_flags + array->size, 0,
+	       ARRAY_GROW_SIZE * sizeof(*new_flags));
+
+	array->data = new_data;
+	array->flags = new_flags;
+	array->size = new_size;
+
+	return(0);
+}
+
+static int _array_last_used(struct array *array)
+{
+	int last;
+
+	if(!array) {
+		return(-EINVAL);
+	}
+
+	for(last = array->size - 1; last >= 0; last--) {
+		if(array->flags[last]) {
+			break;
+		}
+	}
+
+	return(last);
+}
+
+static int _array_shrink(struct array *array)
+{
+	int unused_tail;
+	int new_size;
+	void **new_data;
+	char *new_flags;
+
+	if(!array) {
+		return(-EINVAL);
+	}
+
+	new_data = NULL;
+	new_flags = NULL;
+
+	unused_tail = array->size - _array_last_used(array);
+
+	if(unused_tail < ARRAY_SHRINK_SIZE) {
+		return(0);
+	}
+
+	unused_tail -= unused_tail % ARRAY_SHRINK_SIZE;
+	new_size = array->size - unused_tail;
+
+	if(new_size > 0) {
+		new_data = malloc(new_size * sizeof(*new_data));
+
+		if(!new_data) {
+			return(-ENOMEM);
+		}
+
+		new_flags = malloc(new_size * sizeof(*new_flags));
+
+		if(!new_flags) {
+			free(new_data);
+			return(-ENOMEM);
+		}
+
+		memcpy(new_data, array->data,
+		       new_size * sizeof(*new_data));
+		memcpy(new_flags, array->flags,
+		       new_size * sizeof(*new_flags));
+	}
+
+	free(array->data);
+	free(array->flags);
+
+	array->data = new_data;
+	array->flags = new_flags;
+	array->size = new_size;
+
+	return(0);
+}
+
+int array_new(struct array **array)
+{
+	struct array *a;
+
+	if(!array) {
+		return(-EINVAL);
+	}
+
+	a = malloc(sizeof(*a));
+
+	if(!a) {
+		return(-ENOMEM);
+	}
+
+	memset(a, 0, sizeof(*a));
+
+	if(_array_grow(a) < 0) {
+		free(a);
+		return(-ENOMEM);
+	}
+
+	*array = a;
+	return(0);
+}
+
+int array_free(struct array **array)
+{
+	if(!array) {
+		return(-EINVAL);
+	}
+
+	if(!*array) {
+		return(-EALREADY);
+	}
+
+	if((*array)->data) {
+		free((*array)->data);
+	}
+	if((*array)->flags) {
+		free((*array)->flags);
+	}
+
+	free(*array);
+	*array = NULL;
+
+	return(0);
+}
+
+int array_set(struct array *array, int idx, void *data)
+{
+	if(!array) {
+		return(-EINVAL);
+	}
+
+	while(idx > array->size) {
+		if(_array_grow(array) < 0) {
+			return(-ENOMEM);
+		}
+	}
+
+	array->data[idx] = data;
+	array->flags[idx] = 1;
+
+	return(0);
+}
+
+int array_get(struct array *array, int idx, void **data)
+{
+	int real_idx;
+
+	if(!array || !data) {
+		return(-EINVAL);
+	}
+
+	if(array->size == 0) {
+		return(-ENODATA);
+	}
+
+	real_idx = idx % array->size;
+	*data = array->data[real_idx];
+
+	return(0);
+}
+
+int array_take(struct array *array, int idx, void **data)
+{
+	int real_idx;
+
+	if(!array) {
+		return(-EINVAL);
+	}
+
+	if(array->size == 0) {
+		return(-ENODATA);
+	}
+
+	real_idx = idx % array->size;
+
+	if(data) {
+		*data = array->data[real_idx];
+	}
+
+	array->flags[real_idx] = 0;
+	_array_shrink(array);
+
+	return(0);
+}
diff --git a/array.h b/array.h
new file mode 100644
index 0000000..8b15d80
--- /dev/null
+++ b/array.h
@@ -0,0 +1,13 @@
+#ifndef ARRAY_H
+#define ARRAY_H
+
+struct array;
+
+int array_new(struct array **array);
+int array_free(struct array **array);
+
+int array_set(struct array*, int, void*);
+int array_get(struct array*, int, void**);
+int array_take(struct array*, int, void**);
+
+#endif /* ARRAY_H */