X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=dosdemo;a=blobdiff_plain;f=src%2Fdarray.c;fp=src%2Fdarray.c;h=66c071524d429627556e94d2eeaa61c34a3c60b8;hp=0000000000000000000000000000000000000000;hb=dfc6ebacd7bcc1e6b9e7168c3e4824d241d2d5c8;hpb=0aeee13aa695ec617ec22253824f17209660bd39

diff --git a/src/darray.c b/src/darray.c
new file mode 100644
index 0000000..66c0715
--- /dev/null
+++ b/src/darray.c
@@ -0,0 +1,122 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "darray.h"
+#include "util.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 *darr_alloc(int elem, int szelem)
+{
+	struct arrdesc *desc;
+
+	desc = malloc_nf(elem * szelem + sizeof *desc);
+	desc->nelem = desc->max_elem = elem;
+	desc->szelem = szelem;
+	desc->bufsz = elem * szelem;
+	return (char*)desc + sizeof *desc;
+}
+
+void darr_free(void *da)
+{
+	if(da) {
+		free(DESC(da));
+	}
+}
+
+void *darr_resize_impl(void *da, int elem)
+{
+	int newsz;
+	struct arrdesc *desc;
+
+	if(!da) return 0;
+	desc = DESC(da);
+
+	newsz = desc->szelem * elem;
+	desc = realloc_nf(desc, newsz + sizeof *desc);
+
+	desc->nelem = desc->max_elem = elem;
+	desc->bufsz = newsz;
+	return (char*)desc + sizeof *desc;
+}
+
+int darr_empty(void *da)
+{
+	return DESC(da)->nelem ? 0 : 1;
+}
+
+int darr_size(void *da)
+{
+	return DESC(da)->nelem;
+}
+
+
+void *darr_clear_impl(void *da)
+{
+	return darr_resize_impl(da, 0);
+}
+
+/* stack semantics */
+void *darr_push_impl(void *da, void *item)
+{
+	struct arrdesc *desc;
+	int nelem;
+
+	desc = DESC(da);
+	nelem = desc->nelem;
+
+	if(nelem >= desc->max_elem) {
+		/* need to resize */
+		int newsz = desc->max_elem ? desc->max_elem * 2 : 1;
+
+		da = darr_resize_impl(da, newsz);
+		desc = DESC(da);
+		desc->nelem = nelem;
+	}
+
+	if(item) {
+		memcpy((char*)da + desc->nelem * desc->szelem, item, desc->szelem);
+	}
+	desc->nelem++;
+	return da;
+}
+
+void *darr_pop_impl(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 */
+		int newsz = desc->max_elem / 2;
+
+		da = darr_resize_impl(da, newsz);
+		desc = DESC(da);
+		desc->nelem = nelem;
+	}
+	desc->nelem--;
+
+	return da;
+}
+
+void *darr_finalize(void *da)
+{
+	struct arrdesc *desc = DESC(da);
+	memmove(desc, da, desc->bufsz);
+	return desc;
+}