X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=eradicate;a=blobdiff_plain;f=src%2Fdynarr.c;fp=src%2Fdynarr.c;h=09a5e455e4369ac37063250d45450267c4bad8c2;hp=0000000000000000000000000000000000000000;hb=879478749c2f426394d3d995ee6c079b3d9394e8;hpb=c667edc1da370d08d0af162adfdcb31ceae522ab

diff --git a/src/dynarr.c b/src/dynarr.c
new file mode 100644
index 0000000..09a5e45
--- /dev/null
+++ b/src/dynarr.c
@@ -0,0 +1,140 @@
+/* dynarr - dynamic resizable C array data structure
+ * author: John Tsiombikas <nuclear@member.fsf.org>
+ * license: public domain
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "dynarr.h"
+
+/* The array descriptor keeps auxilliary information needed to manipulate
+ * the dynamic array. It's allocated adjacent to the array buffer.
+ */
+struct arrdesc {
+	int nelem, szelem;
+	int max_elem;
+	int bufsz;	/* not including the descriptor */
+};
+
+#define DESC(x)		((struct arrdesc*)((char*)(x) - sizeof(struct arrdesc)))
+
+void *dynarr_alloc(int elem, int szelem)
+{
+	struct arrdesc *desc;
+
+	if(!(desc = malloc(elem * szelem + sizeof *desc))) {
+		return 0;
+	}
+	desc->nelem = desc->max_elem = elem;
+	desc->szelem = szelem;
+	desc->bufsz = elem * szelem;
+	return (char*)desc + sizeof *desc;
+}
+
+void dynarr_free(void *da)
+{
+	if(da) {
+		free(DESC(da));
+	}
+}
+
+void *dynarr_resize(void *da, int elem)
+{
+	int newsz;
+	void *tmp;
+	struct arrdesc *desc;
+
+	if(!da) return 0;
+	desc = DESC(da);
+
+	newsz = desc->szelem * elem;
+
+	if(!(tmp = realloc(desc, newsz + sizeof *desc))) {
+		return 0;
+	}
+	desc = tmp;
+
+	desc->nelem = desc->max_elem = elem;
+	desc->bufsz = newsz;
+	return (char*)desc + sizeof *desc;
+}
+
+int dynarr_empty(void *da)
+{
+	return DESC(da)->nelem ? 0 : 1;
+}
+
+int dynarr_size(void *da)
+{
+	return DESC(da)->nelem;
+}
+
+
+void *dynarr_clear(void *da)
+{
+	return dynarr_resize(da, 0);
+}
+
+/* stack semantics */
+void *dynarr_push(void *da, void *item)
+{
+	struct arrdesc *desc;
+	int nelem;
+
+	desc = DESC(da);
+	nelem = desc->nelem;
+
+	if(nelem >= desc->max_elem) {
+		/* need to resize */
+		struct arrdesc *tmp;
+		int newsz = desc->max_elem ? desc->max_elem * 2 : 1;
+
+		if(!(tmp = dynarr_resize(da, newsz))) {
+			fprintf(stderr, "failed to resize\n");
+			return da;
+		}
+		da = tmp;
+		desc = DESC(da);
+		desc->nelem = nelem;
+	}
+
+	if(item) {
+		memcpy((char*)da + desc->nelem++ * desc->szelem, item, desc->szelem);
+	}
+	return da;
+}
+
+void *dynarr_pop(void *da)
+{
+	struct arrdesc *desc;
+	int nelem;
+
+	desc = DESC(da);
+	nelem = desc->nelem;
+
+	if(!nelem) return da;
+
+	if(nelem <= desc->max_elem / 3) {
+		/* reclaim space */
+		struct arrdesc *tmp;
+		int newsz = desc->max_elem / 2;
+
+		if(!(tmp = dynarr_resize(da, newsz))) {
+			fprintf(stderr, "failed to resize\n");
+			return da;
+		}
+		da = tmp;
+		desc = DESC(da);
+		desc->nelem = nelem;
+	}
+	desc->nelem--;
+
+	return da;
+}
+
+void *dynarr_finalize(void *da)
+{
+	struct arrdesc *desc = DESC(da);
+	memmove(desc, da, desc->bufsz);
+	return desc;
+}