bdlb_bigendian

Functions
	bdlb::BigEndianInt16::operator short () const
	bdlb::BigEndianUint16::operator unsigned short () const
	bdlb::BigEndianInt32::operator int () const
	bdlb::BigEndianUint32::operator unsigned int () const
	bdlb::BigEndianInt64::operator bsls::Types::Int64 () const
	bdlb::BigEndianUint64::operator bsls::Types::Uint64 () const

Detailed Description

Outline

• Purpose
• Classes
• Description
  • Usage
    • Example 1: Basic Use of bdlb::BigEndian

Purpose

Provide big-endian integer types.

Classes

• bdlb::BigEndianInt16: signed 16-bit in-core big-endian integer
• bdlb::BigEndianUint16: unsigned 16-bit in-core big-endian integer
• bdlb::BigEndianInt32: signed 32-bit in-core big-endian integer
• bdlb::BigEndianUint32: unsigned 32-bit in-core big-endian integer
• bdlb::BigEndianInt64: signed 64-bit in-core big-endian integer
• bdlb::BigEndianUint64: unsigned 64-bit in-core big-endian integer

See also

bsls_types

Description

This component provides generic in-core big-endian integer types bdlb::BigEndianInt16, bdlb::BigEndianUint16, bdlb::BigEndianInt32, bdlb::BigEndianUint32, bdlb::BigEndianInt64 and bdlb::BigEndianUint64 that store integral values that they represent in a big-endian byte order. For example, an integer value 0x01020304 will be internally stored by the bdlb::BigEndianInt32 object as 0x04030201 on little-endian platforms.

Usage

This section illustrates intended use of this component.

Example 1: Basic Use of bdlb::BigEndian

This example demonstrates using bdlb::BigEndian types to represent a structure meant to be exchanged over the network ( which historically uses big-endian byte order ) or stored in-core as big-endian integers. First, we define the structure:

/// This structure represents the header of the protocol.  All integer
/// values are stored in the network byte-order (i.e., big-endian).
struct ProtocolHeader {
 
    bdlb::BigEndianUint16 d_protocolVersion;
    bdlb::BigEndianUint16 d_messageType;
    bdlb::BigEndianUint32 d_messageLength;
};

Next, we prepare in-memory representation of the protocol header with protocol version set to 0x1, message type set to 0x02 and message length set to 0x1234 in the big-endian byte order (most significant bytes first):

const char buffer[8] = { 0x00, 0x01, 0x00, 0x02, 0x00, 0x00, 0x12, 0x34 };

Now, we create an instance of the ProtocolHeader structure and emulate packet reception over the network:

struct ProtocolHeader header;
assert(8 == sizeof(header));
memcpy(static_cast<void*>(&header), buffer, 8);

Next, we verify that actual in-core values depend on the endianess of the underlying platform:

#ifdef BSLS_PLATFORM_IS_LITTLE_ENDIAN
assert(0x0100 ==
       static_cast<short>(*(reinterpret_cast<unsigned short*>(
                                             &header.d_protocolVersion))));
 
assert(0x0200 ==
       static_cast<short>(*(reinterpret_cast<unsigned short*>(
                                             &header.d_messageType))));
 
assert(0x34120000 == *(reinterpret_cast<unsigned int*>(
                                             &header.d_messageLength)));
#endif // BSLS_PLATFORM_IS_LITTLE_ENDIAN
 
#ifdef BSLS_PLATFORM_IS_BIG_ENDIAN
assert(0x01 ==
       static_cast<short>(*(reinterpret_cast<unsigned short*>(
                                             &header.d_protocolVersion))));
 
assert(0x02 ==
       static_cast<short>(*(reinterpret_cast<unsigned short*>(
                                             &header.d_messageType))));
 
assert(0x1234 == *(reinterpret_cast<unsigned int*>(
                                             &header.d_messageLength)));
#endif // BSLS_PLATFORM_IS_BIG_ENDIAN

Finally, we verify that the received protocol header can be validated on platforms of any endianess:

assert(0x01   == header.d_protocolVersion);
assert(0x02   == header.d_messageType);
assert(0x1234 == header.d_messageLength);

Function Documentation

operator bsls::Types::Int64()

bdlb::BigEndianInt64::operator bsls::Types::Int64 ( ) const

inline

Return the value stored in this object as a bsls::Types::Int64 in the native byte-order.

operator bsls::Types::Uint64()

bdlb::BigEndianUint64::operator bsls::Types::Uint64 ( ) const

inline

Return the value stored in this object as a bsls::Types::Uint64 in the native byte-order.

operator int()

bdlb::BigEndianInt32::operator int ( ) const

inline

Return the value stored in this object as a int in the native byte-order.

operator short()

bdlb::BigEndianInt16::operator short ( ) const

inline

Return the value stored in this object as a short in the native byte-order.

operator unsigned int()

bdlb::BigEndianUint32::operator unsigned int ( ) const

inline

Return the value stored in this object as a unsigned int in the native byte-order.

operator unsigned short()

bdlb::BigEndianUint16::operator unsigned short ( ) const

inline

Return the value stored in this object as a unsigned short in the native byte-order.