C/C++编程-工程实践-MDK工具学习

工程配置

从 mdk6 开始，采用CLANG 编译器 和 LLVM 编译架构。

C语言的标准库

标准库的分类，及简介

分为

• C 和C++ 动态运行库 （C and C++ runtime libraries）
  • Standard C library
  • C micro-library
  • C++
• 独立的C库 （standalone C library function）

Arm C 和 C++ 库的目录结构

库安装在<install_directory>/lib 路径下 armlib 和 libcxx 文件夹内

armlib

包含Arm C 库的变体（Arm C Library）、浮点计算库（floating-point arithmetic library 【fplib】）、 数学库（math library【mathlib】）

libcxx

包含 所有的 libc++ 和 libc++abi 库

库的头文件安装在<install_directory>/include路径下。

兼容ARM架构的二进制应用接口（Compliance with the Application Binary Interface (ABI) for the Arm architecture）

此组规范规定了一些特定兼容性规范。

1. the C Library ABI for the Arm Architecture（CLIBABI）
2. the Base Standard ABI for the Arm Architecture（BSABI）
3. the libc++ library conforms to the C++ ABI for the Arm Architecture(CPPABI)

【解读】：MDK中对标准库的支持是采用静态二进制的加载方式，如果对其api跳转的话，只能跳到***.h文件。 并且以extern _ARMABI 方式进行声明。举例如下：

extern _ARMABI void *memcpy(void * __restrict /*s1*/,
                   const void * __restrict /*s2*/, size_t /*n*/) __attribute__((__nonnull__(1,2)));
  /*
   * copies n characters from the object pointed to by s2 into the object
   * pointed to by s1. If copying takes place between objects that overlap,
   * the behaviour is undefined.
   * Returns: the value of s1.
   */
extern _ARMABI void *memmove(void * /*s1*/,
                   const void * /*s2*/, size_t /*n*/) __attribute__((__nonnull__(1,2)));
  /*
   * copies n characters from the object pointed to by s2 into the object
   * pointed to by s1. Copying takes place as if the n characters from the
   * object pointed to by s2 are first copied into a temporary array of n
   * characters that does not overlap the objects pointed to by s1 and s2,
   * and then the n characters from the temporary array are copied into the
   * object pointed to by s1.
   * Returns: the value of s1.
   */
extern _ARMABI char *strcpy(char * __restrict /*s1*/, const char * __restrict /*s2*/) __attribute__((__nonnull__(1,2)));
  /*
   * copies the string pointed to by s2 (including the terminating nul
   * character) into the array pointed to by s1. If copying takes place
   * between objects that overlap, the behaviour is undefined.
   * Returns: the value of s1.
   */
extern _ARMABI char *strncpy(char * __restrict /*s1*/, const char * __restrict /*s2*/, size_t /*n*/) __attribute__((__nonnull__(1,2)));
  /*
   * copies not more than n characters (characters that follow a null
   * character are not copied) from the array pointed to by s2 into the array
   * pointed to by s1. If copying takes place between objects that overlap,
   * the behaviour is undefined.
   * Returns: the value of s1.
   */

包涵string.h、

1. string.h

#ifndef __string_h			/* 1. 预防重复加载 */
#define __string_h
#define __ARMCLIB_VERSION 6180002	/* 2. 版本控制 */

/* _ARMABI 译为Application Binary Interface for the ARM Architecture */
#define _ARMABI __attribute__((__nothrow__))

  #ifndef __STRING_DECLS
  #define __STRING_DECLS