Dynbuf dynamic buffer/array/vector sample code

dynbuf/dynbuf.c

@@ -0,0 +1,79 @@
+#include "dynbuf.h"
+#include <stdio.h>
+
+#ifndef GROWTH_FACTOR
+#define GROWTH_FACTOR 2
+#endif
+
+#ifndef INITIAL_CAPACITY
+#define INITIAL_CAPACITY 4
+#endif
+
+#ifdef GROWTH_POW2
+#define ROUND_UP_POW2(x) round_up_pow2(x)
+
+static inline int round_up_pow2(int x) {
+    if (x <= 1)
+        return 1;
+
+    x--;
+    x |= x >> 1;
+    x |= x >> 2;
+    x |= x >> 4;
+    x |= x >> 8;
+    x |= x >> 16;
+    return x + 1;
+}
+#else
+#define ROUND_UP_POW2(x) (x)
+#endif
+
+void dynbuf_init(Dynbuf *v, size_t elem_size) {
+    v->elem_size = elem_size;
+    v->length = 0;
+    v->capacity = INITIAL_CAPACITY;
+    v->data = malloc(v->capacity * elem_size);
+    assert(v->data != NULL);
+}
+
+void dynbuf_free(Dynbuf *v) {
+    free(v->data);
+    v->data = NULL;
+    v->length = 0;
+    v->capacity = 0;
+    v->elem_size = 0;
+}
+
+void dynbuf_push(Dynbuf *v, const void *elem) {
+    if (v->length == v->capacity) {
+        dynbuf_resize(v, ROUND_UP_POW2(v->capacity * GROWTH_FACTOR));
+    }
+
+    memcpy((char *)v->data + v->length * v->elem_size, elem, v->elem_size);
+    v->length++;
+}
+
+void dynbuf_resize(Dynbuf *v, size_t newcap) {
+    printf("Resize to %zu\n", newcap);
+
+    if (newcap > v->capacity) {
+        v->capacity = newcap;
+        v->data = realloc(v->data, v->capacity * v->elem_size);
+        assert(v->data != NULL);
+    }
+}
+
+void dynbuf_pop(Dynbuf *v) {
+    if (v->length > 0) {
+        v->length--;
+    }
+}
+
+void *dynbuf_get(Dynbuf *v, size_t index) {
+    assert(index < v->length);
+    return (char *)v->data + index * v->elem_size;
+}
+
+inline size_t dynbuf_size(const Dynbuf *v) { return v->length; }
+
+inline size_t dynbuf_capacity(const Dynbuf *v) { return v->capacity; }