first pass at basic buffer functionality

Buffer.cc

@@ -6,6 +6,35 @@
 #include "Buffer.h"
 
 namespace kge {
+
+
+constexpr size_t	defaultCapacity = 32;
+constexpr size_t	maxReasonableLine = 8192;
+
+
+Buffer::Buffer()
+    : contents(nullptr), length(0), capacity(0)
+{
+	this->Resize(defaultCapacity);			
+}
+
+
+Buffer::Buffer(size_t initialCapacity)
+    : contents(nullptr), length(0), capacity(0)
+{
+	this->Resize(initialCapacity);			
+}
+
+
+Buffer::Buffer(const char *data)
+    : contents(nullptr), length(0), capacity(0)
+{
+	size_t	datalen = strnlen(data, maxReasonableLine);
+
+	this->Append(data, datalen);
+}
+
+
 uint8_t *
 Buffer::Contents()
 {
@@ -15,25 +44,43 @@ Buffer::Contents()
 bool
 Buffer::Append(uint8_t *data, size_t datalen)
 {
-	return false;
+	auto	resized = false;
+	auto	newCap = this->mustGrow(datalen);
+
+	if (newCap > 0) {
+		this->Resize(newCap);
+		resized = true;
+	}
+
+	memcpy(this->contents + this->length, data, datalen);
+	this->length += datalen;
+	return resized;
 }
 
 bool
 Buffer::Append(uint8_t c)
 {
-	return false;
+	return this->Append(&c, 1);
 }
 
 bool
 Buffer::Insert(size_t index, uint8_t *data, size_t datalen)
 {
-	return false;
+	auto	resized = this->shift(index, datalen);
+
+	if (newCap > 0) {
+		this->Resize(newCap);
+		resized = true;
+	}
+
+	memcpy(this->contents + index, data, datalen);
+	return resized;
 }
 
 bool
 Buffer::Insert(size_t index, uint8_t c)
 {
-	return false;
+	return this->Insert(index, &c, 1);
 }
 
 size_t
@@ -51,8 +98,14 @@ Buffer::Resize(size_t newCapacity)
 
 	uint8_t *newContents = new uint8_t[newCapacity];
 
-	memcpy(newContents, this->contents, this->length);
-	delete this->contents;
+	if (this->length > 0) {
+		memcpy(newContents, this->contents, this->length);
+	}
+
+	if (this->contents != nullptr) {
+		delete this->contents;
+	}
+
 	this->contents = newContents;
 	this->capacity = newCapacity;
 }
@@ -82,11 +135,44 @@ Buffer::Reclaim()
 	this->capacity = 0;
 }
 
-bool
-Buffer::mustGrow(size_t newLength)
+size_t
+Buffer::mustGrow(size_t delta)
 {
-	return (newLength + this->length) >= this->capacity;
+	if ((delta + this->length) < this->capacity) {
+		return 0;
+	}
+
+	auto newCapacity = delta + this->length;
+	newCapacity--;
+
+	newCapacity |= newCapacity >> 1;
+	newCapacity |= newCapacity >> 2;
+	newCapacity |= newCapacity >> 4;
+	newCapacity |= newCapacity >> 8;
+	newCapacity |= newCapacity >> 16;
+	newCapacity |= newCapacity >> 32;
+	return newCapacity;
 }
 
 
-} // kge
+bool
+Buffer:shift(size_t offset, size_t delta)
+{
+	auto	resized = false;
+	auto	newCap = this->mustGrow(delta);
+
+	if (newCap > 0) {
+		this->Resize(newCap);
+		resized = true;
+	}
+
+	
+	for (size_t i = this->length; i >= offset; i++) {
+		this->contents[i+delta] = this->contents[i];
+	}
+
+	return resized;
+}
+
+
+} // kge