library Buffer {
    struct buffer {
        bytes buf;
        uint capacity;
    }

    function init(buffer memory buf, uint capacity) internal constant {
        if(capacity % 32 != 0) capacity += 32 - (capacity % 32);
        // Allocate space for the buffer data
        buf.capacity = capacity;
        assembly {
            let ptr := mload(0x40)
            mstore(buf, ptr)
            mstore(0x40, add(ptr, capacity))
        }
    }

    function resize(buffer memory buf, uint capacity) private constant {
        bytes memory oldbuf = buf.buf;
        init(buf, capacity);
        append(buf, oldbuf);
    }

    function max(uint a, uint b) private constant returns(uint) {
        if(a > b) {
            return a;
        }
        return b;
    }

    /**
     * @dev Appends a byte array to the end of the buffer. Reverts if doing so
     *      would exceed the capacity of the buffer.
     * @param buf The buffer to append to.
     * @param data The data to append.
     * @return The original buffer.
     */
    function append(buffer memory buf, bytes data) internal constant returns(buffer memory) {
        if(data.length + buf.buf.length > buf.capacity) {
            resize(buf, max(buf.capacity, data.length) * 2);
        }

        uint dest;
        uint src;
        uint len = data.length;
        assembly {
            // Memory address of the buffer data
            let bufptr := mload(buf)
            // Length of existing buffer data
            let buflen := mload(bufptr)
            // Start address = buffer address + buffer length + sizeof(buffer length)
            dest := add(add(bufptr, buflen), 32)
            // Update buffer length
            mstore(bufptr, add(buflen, mload(data)))
            src := add(data, 32)
        }

        // Copy word-length chunks while possible
        for(; len >= 32; len -= 32) {
            assembly {
                mstore(dest, mload(src))
            }
            dest += 32;
            src += 32;
        }

        // Copy remaining bytes
        uint mask = 256 ** (32 - len) - 1;
        assembly {
            let srcpart := and(mload(src), not(mask))
            let destpart := and(mload(dest), mask)
            mstore(dest, or(destpart, srcpart))
        }

        return buf;
    }

    /**
     * @dev Appends a byte to the end of the buffer. Reverts if doing so would
     * exceed the capacity of the buffer.
     * @param buf The buffer to append to.
     * @param data The data to append.
     * @return The original buffer.
     */
    function append(buffer memory buf, uint8 data) internal constant {
        if(buf.buf.length + 1 > buf.capacity) {
            resize(buf, buf.capacity * 2);
        }

        assembly {
            // Memory address of the buffer data
            let bufptr := mload(buf)
            // Length of existing buffer data
            let buflen := mload(bufptr)
            // Address = buffer address + buffer length + sizeof(buffer length)
            let dest := add(add(bufptr, buflen), 32)
            mstore8(dest, data)
            // Update buffer length
            mstore(bufptr, add(buflen, 1))
        }
    }

    /**
     * @dev Appends a byte to the end of the buffer. Reverts if doing so would
     * exceed the capacity of the buffer.
     * @param buf The buffer to append to.
     * @param data The data to append.
     * @return The original buffer.
     */
    function appendInt(buffer memory buf, uint data, uint len) internal constant returns(buffer memory) {
        if(len + buf.buf.length > buf.capacity) {
            resize(buf, max(buf.capacity, len) * 2);
        }

        uint mask = 256 ** len - 1;
        assembly {
            // Memory address of the buffer data
            let bufptr := mload(buf)
            // Length of existing buffer data
            let buflen := mload(bufptr)
            // Address = buffer address + buffer length + sizeof(buffer length) + len
            let dest := add(add(bufptr, buflen), len)
            mstore(dest, or(and(mload(dest), not(mask)), data))
            // Update buffer length
            mstore(bufptr, add(buflen, len))
        }
        return buf;
    }
}
function append(buffer memory buf, bytes data) internal constant returns(buffer memory) {
    if(data.length + buf.buf.length > buf.capacity) {
        resize(buf, max(buf.capacity, data.length) * 2);
    }

    uint dest;
    uint src;
    uint len = data.length;
    assembly {
        // Memory address of the buffer data
        let bufptr := mload(buf)
        // Length of existing buffer data
        let buflen := mload(bufptr)
        // Start address = buffer address + buffer length + sizeof(buffer length)
        dest := add(add(bufptr, buflen), 32)
        // Update buffer length
        mstore(bufptr, add(buflen, mload(data)))
        src := add(data, 32)
    }

    // Copy word-length chunks while possible
    for(; len >= 32; len -= 32) {
        assembly {
            mstore(dest, mload(src))
        }
        dest += 32;
        src += 32;
    }

    // Copy remaining bytes
    uint mask = 256 ** (32 - len) - 1;
    assembly {
        let srcpart := and(mload(src), not(mask))
        let destpart := and(mload(dest), mask)
        mstore(dest, or(destpart, srcpart))
    }

    return buf;
}

/**
 * @dev Appends a byte array to the end of the buffer. Reverts if doing so
 *      would exceed the capacity of the buffer.
 * @param buf The buffer to append to.
 * @param data The data to append.
 * @return The original buffer.
 */