Add DBuf , buffer API

src/dbuf.c

@@ -0,0 +1,111 @@
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include "ucore/dbuf.h"
+
+void
+uc_dbuf_free(DBuf *buf)
+{
+	if(buf != NULL)
+		free(buf->bufstart);
+
+}
+
+int 
+uc_dbuf_init(DBuf *buf,size_t initlen)
+{
+	unsigned char *tmp = malloc(initlen);
+	if(tmp == NULL)
+		return -1;
+	buf->start = buf->bufstart = buf->end = tmp;
+ 	buf->bufend = tmp + initlen;
+
+	return 0;
+}
+
+size_t 
+uc_dbuf_len(DBuf *buf)
+{
+	return buf->end - buf->start;
+}
+
+size_t 
+uc_dbuf_buflen(DBuf *buf)
+{
+	return buf->bufend - buf->bufstart;
+}
+
+size_t
+uc_dbuf_remaining(DBuf *buf)
+{
+	return buf->bufend - buf->end;
+}
+
+int
+uc_dbuf_ensure(DBuf *buf,size_t capacity)
+{
+	size_t sz,remaining,len;
+	
+	remaining = uc_dbuf_remaining(buf);
+	if(remaining >= capacity)
+		return 0;
+	len = uc_dbuf_len(buf);
+	sz = buf->start - buf->bufstart;
+	memmove(buf->bufstart,buf->start,len);
+	if(sz + remaining < capacity) {
+		size_t newlen = uc_dbuf_buflen(buf)  + capacity;
+		void *tmp = realloc(buf->bufstart,newlen);
+		if(tmp == NULL)
+			return 1;
+		buf->bufstart = tmp;
+		buf->bufend = buf->bufstart + newlen;
+
+	}
+	buf->start = buf->bufstart;
+	buf->end = buf->start + len;
+	
+	return 0;
+}
+
+void
+uc_dbuf_trim(DBuf *buf)
+{
+	size_t len = uc_dbuf_len(buf);
+	void *tmp;
+
+	if(len == 0)
+		return;
+
+	memmove(buf->bufstart,buf->start,len);
+
+	tmp = realloc(buf->bufstart,len);
+	if(tmp != NULL) 
+		buf->bufstart = tmp;
+
+	buf->start = buf->bufstart;
+	buf->bufend = buf->end = buf->bufstart + len;
+}
+
+int 
+uc_dbuf_take(DBuf *buf,size_t len)
+{
+	size_t buflen = uc_dbuf_len(buf);
+
+	if(len == buflen) {
+		buf->start = buf->end = buf->bufstart;
+	} else if (len < buflen) {
+		buf->start = buf->start + len;
+    } else {
+        //should maybe assert. This is a serious offence
+        return 1; 
+    }
+
+	return 0;
+}
+
+void
+uc_dbuf_added(DBuf *buf,size_t len)
+{
+    assert(len <= uc_dbuf_remaining(buf));
+	buf->end +=len;
+}