Microchip Technology XC8 Standard Compiler (Workstation) SW006021-1 SW006021-1 ユーザーズマニュアル
製品コード
SW006021-1
Common C Interface
2012 Microchip Technology Inc.
DS52053A-page 15
For freestanding implementations – or for what we typically call embedded applications
– the standard allows non-standard extensions to the language, but obviously does not
enforce how they are specified or how they work. When working so closely to the
device hardware, a programmer needs a means of specifying device setup and inter-
rupts, as well as utilizing the often complex world of small-device memory
architectures. This cannot be offered by the standard in a consistent way.
– the standard allows non-standard extensions to the language, but obviously does not
enforce how they are specified or how they work. When working so closely to the
device hardware, a programmer needs a means of specifying device setup and inter-
rupts, as well as utilizing the often complex world of small-device memory
architectures. This cannot be offered by the standard in a consistent way.
While the ANSI C Standard provides a mutual understanding for programmers and
compiler vendors, programmers need to consider the implementation-defined behavior
of their tools and the probability that they may need to use extensions to the C language
that are non-standard. Both of these circumstances can have an impact on code por-
tability.
compiler vendors, programmers need to consider the implementation-defined behavior
of their tools and the probability that they may need to use extensions to the C language
that are non-standard. Both of these circumstances can have an impact on code por-
tability.
2.2.2
The Common C Interface
The Common C Interface (CCI) supplements the ANSI C Standard and makes it easier
for programmers to achieve consistent outcomes on all Microchip devices when using
any of the MPLAB XC C compilers.
for programmers to achieve consistent outcomes on all Microchip devices when using
any of the MPLAB XC C compilers.
It delivers the following improvements, all designed with portability in mind.
Refinement of the ANSI C Standard
The CCI documents specific behavior for some code in which actions are implemen-
tation-defined behavior under the ANSI C Standard. For example, the result of
right-shifting a signed integer is fully defined by the CCI. Note that many
implementation-defined items that closely couple with device characteristics, such as
the size of an int, are not defined by the CCI.
right-shifting a signed integer is fully defined by the CCI. Note that many
implementation-defined items that closely couple with device characteristics, such as
the size of an int, are not defined by the CCI.
Consistent syntax for non-standard extensions
The CCI non-standard extensions are mostly implemented using keywords with a uni-
form syntax. They replace keywords, macros and attributes that are the native com-
piler implementation. The interpretation of the keyword may differ across each com-
piler, and any arguments to the keywords may be device specific.
piler implementation. The interpretation of the keyword may differ across each com-
piler, and any arguments to the keywords may be device specific.
Coding guidelines
The CCI may indicate advice on how code should be written so that it can be ported
to other devices or compilers. While you may choose not to follow the advice, it will
not conform to the CCI.
not conform to the CCI.