View source for Embedded C++

'''Embedded C++''' ('''EC++''') is a [[programming language dialect|dialect]] of the [[C++]] programming language for [[embedded system]]s. It was defined by an industry group led by major Japanese [[central processing unit]] (CPU) manufacturers, including [[NEC Corporation|NEC]], [[Hitachi, Ltd.|Hitachi]], [[Fujitsu]], and [[Toshiba]], to address the shortcomings of C++ for embedded applications. The goal of the effort<ref>{{cite web|title=EC++ Rationale|url=http://www.caravan.net/ec2plus/rationale.html}}</ref> is to preserve the most useful [[object-oriented programming|object-oriented]] features of the C++ language yet minimize code size while maximizing execution efficiency and making [[compiler]] construction simpler. The official website states the goal as "to  provide embedded systems programmers with a subset of C++ that is easy for the average C programmer to understand and use".<ref name=qa>[http://www.caravan.net/ec2plus/question.html EC++ Questions and Answers]</ref>

== Differences from C++ ==
Embedded C++ excludes some features of C++.

{| class="wikitable"
! scope="col" | Feature !! scope="col" | ISO/ANSI C C++ !! scope="col" | Embedded C++
|-
! {{rh2|align=right}} scope="row" | <span style="font-weight:normal">[[Exception handling]]</span>
| {{ya}} || {{na}}
|-
! {{rh2|align=right}} scope="row" | <span style="font-weight:normal">[[Multiple inheritance]]</span>
| {{ya}} || {{na}}
|-
! {{rh2|align=right}} scope="row" | <span style="font-weight:normal"><code>mutable</code>, a [[storage class specifier]]</span>
| {{ya}} || {{na}}
|-
! {{rh2|align=right}} scope="row" | <span style="font-weight:normal">[[Namespaces]]</span>
| {{ya}} || {{na}}
|-
! {{rh2|align=right}} scope="row" | <span style="font-weight:normal">[[Generic programming#Templates in C++|Templates]]</span>
| {{ya}} || {{na}}
|-
! {{rh2|align=right}} scope="row" | <span style="font-weight:normal">[[Run-time type information]] (<code>typeid</code>)</span>
| {{ya}} || {{na}}
|-
! {{rh2|align=right}} scope="row" | <span style="font-weight:normal">Style casts<br>(<code>static_cast</code>, <code>dynamic_cast</code>, <code>reinterpret_cast</code>, and <code>const_cast</code>)</span>
| {{ya}} || {{na}}
|-
! {{rh2|align=right}} scope="row" | <span style="font-weight:normal">[[Virtual base class]]es</span>
| {{ya}} || {{na}}
|}

Some compilers, such as those from Green Hills and IAR Systems, allow certain features of ISO/ANSI C++ to be enabled in Embedded C++. [[IAR Systems]] calls this "Extended Embedded C++".<ref>{{cite web|title=Embedded and Extended Embedded C++ |url=http://www.testech-elect.com/iar/extended_embedded_c++.htm |access-date=9 December 2012 |url-status=dead |archive-url=https://web.archive.org/web/20130521152331/http://www.testech-elect.com/iar/extended_embedded_c++.htm |archive-date=21 May 2013 }}</ref>

=== Compilation ===
An EC++ program can be compiled with any C++ compiler. But, a compiler specific to EC++ may have an easier time doing optimization.

Compilers specific to EC++ are provided by companies such as:
*[[IAR Systems]]<ref>{{cite web
 |     url = http://www.iar.com/ew
 |   title = IAR Systems - Compilers and debuggers
 |    work = IAR Systems website
 }}</ref>
*[[Freescale Semiconductor]], (spin-off from [[Motorola]] in 2004 who had acquired [[Metrowerks]] in 1999)
*Tasking Software,<ref>{{cite web
 |url         = http://www.tasking.com/resources/technologies/compilers/ecpp
 |title       = Embedded C++ compiler technology
 |work        = Tasking website
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20090101140055/http://www.tasking.com/resources/technologies/compilers/ecpp/
 |archive-date = 2009-01-01
}}</ref> part of [[Altium Limited]]
*[[Green Hills Software]]<ref>{{cite web
 |url         = http://www.ghs.com/products/optimizingC++EC++Compilers.html
 |title       = Green Hills Optimizing C/C++/EC++ Compilers
 |work        = Green Hills Software website
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20081025094812/http://www.ghs.com/products/optimizingC++EC++Compilers.html
 |archive-date = 2008-10-25
}}</ref>

== Criticism ==
{{criticism section|date=May 2018}}
The language has had a poor reception with many expert C++ programmers. In particular, [[Bjarne Stroustrup]] says, "To the best of my knowledge EC++ is dead (2004), and if it isn't it ought to be."<ref>{{cite web
 |     url =http://www.stroustrup.com/bs_faq.html#EC++
 |   title = What do you think of EC++?
 |    work = [[Bjarne Stroustrup]]'s FAQ
 }}</ref> In fact, the official English EC++ website has not been updated since 2002. Nevertheless, a restricted subset of C++ (based on Embedded C++) has been adopted by [[Apple Inc.]] as the exclusive programming language to create all [[XNU#I/O Kit|I/O Kit]] device drivers for Apple's macOS, iPadOS and iOS operating systems of the popular Macintosh, iPhone, and iPad products.<ref>{{cite web
 |     url =http://osxbook.com/book/bonus/ancient/whatismacosx/arch_xnu.html
 |     title =What is Mac OS X?
 |     work =Amit Singh
 |     access-date =2015-03-04
 |     archive-date =2019-04-19
 |     archive-url =https://web.archive.org/web/20190419152142/http://osxbook.com/book/bonus/ancient/whatismacosx/arch_xnu.html
 |     url-status =dead
 }}</ref> Apple engineers felt the exceptions, multiple inheritance, templates, and runtime type information features of standard C++ were either insufficient or not efficient enough for use in a high-performance, multithreaded kernel.<ref>{{cite web
 |     url =https://developer.apple.com/library/mac/documentation/DeviceDrivers/Conceptual/WritingDeviceDriver/CPluPlusRuntime/CPlusPlusRuntime.html#//apple_ref/doc/uid/TP30000695-BAJIBFDE
 |   title = The libkern C++ Runtime
 |    work = IOKit Device Driver Design Guidelines
 }}</ref>

== References==
{{reflist}}

== External links ==
* {{official website|www.caravan.net/ec2plus}}
* [http://www.caravan.net/ec2plus/objectives/object.html Background and Objectives of the Embedded C++ Specification Development]
* [http://www.embedded.com/design/prototyping-and-development/4017902/Embedded-C--Yields-Faster-Smaller-Code Embedded C++ Yields Faster Smaller Code], John Carbone (Embedded.com), June 19, 1998
* [http://www.embedded.com/design/embedded/4007119/Building-Bare-Metal-ARM-Systems-with-GNU-Part-1--Getting-Started Building Bare-Metal ARM Systems with GNU: Part 1 - Getting Started], Miro Samek, Quantum Leaps, June 26, 2007
* [http://www.open-std.org/jtc1/sc22/wg21/docs/TR18015.pdf Technical Report on C++ Performance], by WG 21 of ISO Subcommittee SC 22

[[Category:C++ programming language family]]
[[Category:Class-based programming languages|C++]]
[[Category:Hardware description languages]]
[[Category:Embedded systems]]

{{C++ programming language}}
{{Embedded systems}}