project_files/frontlib/buffer.c
changeset 7162 fe76d24a25d7
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/project_files/frontlib/buffer.c	Sat Jun 02 14:26:52 2012 +0200
@@ -0,0 +1,90 @@
+#include "buffer.h"
+#include "logging.h"
+
+#include <stdlib.h>
+#include <limits.h>
+#include <string.h>
+
+typedef struct _flib_vector {
+	void *data;
+	size_t size;
+	size_t capacity;
+} _flib_vector;
+
+flib_vector flib_vector_create() {
+	flib_vector result = malloc(sizeof(_flib_vector));
+	if(result == NULL) {
+		return NULL;
+	}
+	result->data = malloc(16);
+	if(result->data == NULL) {
+		free(result);
+		return NULL;
+	}
+	result->size = 0;
+	result->capacity = 16;
+	return result;
+}
+
+void flib_vector_destroy(flib_vector *vec) {
+	if(vec && *vec) {
+		free((*vec)->data);
+		free(*vec);
+		*vec = NULL;
+	}
+}
+
+static void try_realloc(flib_vector vec, size_t newCapacity) {
+	void *newData = realloc(vec->data, newCapacity);
+	if(newData) {
+		vec->data = newData;
+		vec->capacity = newCapacity;
+	}
+}
+
+static size_t getFreeCapacity(flib_vector vec) {
+	return vec->capacity - vec->size;
+}
+
+int flib_vector_append(flib_vector vec, const void *data, size_t len) {
+	if(getFreeCapacity(vec) < len) {
+		// Resize exponentially for constant amortized time,
+		// But at least by as much as we need of course,
+		// and be extra careful with integer overflows...
+		size_t extraCapacity = (vec->capacity)/2;
+
+		size_t minExtraCapacity = len - getFreeCapacity(vec);
+		if(extraCapacity < minExtraCapacity) {
+			extraCapacity = minExtraCapacity;
+		}
+
+		if(extraCapacity <= SIZE_MAX - vec->capacity) {
+			try_realloc(vec, vec->capacity+extraCapacity);
+		}
+
+		// Check if we were able to resize.
+		// If not, try to allocate at least what we need...
+		if(getFreeCapacity(vec) < len) {
+			try_realloc(vec, vec->capacity+minExtraCapacity);
+
+			// Still not working? Then we fail.
+			if(getFreeCapacity(vec) < len) {
+				return 0;
+			}
+		}
+	}
+
+	memmove(vec->data + vec->size, data, len);
+	vec->size += len;
+	return len;
+}
+
+flib_buffer flib_vector_as_buffer(flib_vector vec) {
+	flib_buffer result = {vec->data, vec->size};
+	return result;
+}
+
+flib_constbuffer flib_vector_as_constbuffer(flib_vector vec) {
+	flib_constbuffer result = {vec->data, vec->size};
+	return result;
+}