libjpeg移植

最近毕设需要用到libjpeg库，安装过程遇到不少问题，因此记录下来，以备将来用。

在下载的是最新的v8版本，费了一番周折没安装成功，故下载了老版本的6b。

step1:下载并解压jpeg源代码包

step2:
 #cd ./jpeg-6b
 #./configure --prefix=/home/jpeg_arm --exec-prefix=/home/jpeg_arm --enable-shared --enable-static
 下面分别介绍这几个参数的作用:
 
 --prefix=/home/jpeg_arm/include : 执行make install 后,会将与体系无关的文件拷贝到此目录下,具体如下:
 /home/jpeg_arm_include.....................................
        |
       +---include........................................
             |
             ---jconfig.h
             |
             ---jerror.h
             |
             ---jmorecfg.h
             |
             ---jpeglib.h
       +---man............................................
             |
            +---man1.......................................
                  |
                  ---cjeg.1
                  |
                  ---djpeg.1
                  |
                  ---jpegtran.1
                  |
                  ---rdjpgcom.1
                  |
                  ---wrjpgcom.1
               
 --exec-prefix=/home/jpeg_arm/lib : 执行make install 后,会将与体系无关的文件拷贝到此目录下,即将一些可执行程序、动态链接库和静态链接库拷贝到此目录的相应目录下，具体如下：
 /home/jpeg_arm_lib........................................
        |
       +---bin............................................
             |
             ---cjeg
             |
             ---djpeg
             |
             ---jpegtran
             |
             ---rdjpgcom
             |
             ---wrjpgcom
       +---lib...........................................
             |
             ---libjpeg.la
             |
             ---libjpeg.so 
             |
             ---libjpeg.so.62
             |
             ---libjpeg.so.62.0.0 
           
 --enable-shared : 用GNU libtool编译成动态链接库 。下面分别对应有无此参数所生成的Makefile的比较:
       ------------------------------------------------------------------------------------------- 
              无--enable-shared参数             |               有--enable-shared参数
       ------------------------------------------------------------------------------------------- 
                          LIBTOOL =                   |            LIBTOOL = ./libtool
       -------------------------------------------------------------------------------------------
                           O = o  A = a                 |            O = lo    A = la
       -------------------------------------------------------------------------------------------
                          LN= $(CC)                    |      LN= $(LIBTOOL) --mode=link $(CC)
       -------------------------------------------------------------------------------------------
    INSTALL_PROGRAM= ${INSTALL}     |  INSTALL_PROGRAM= $(LIBTOOL) --mode=install ${INSTALL}
        INSTALL_LIB= ${INSTALL} -m 644  |  INSTALL_LIB= $(LIBTOOL) --mode=install ${INSTALL}
      -------------------------------------------------------------------------------------------------------
           无参数:

  #  $(LIBTOOL) --mode=compile $(CC) $(CFLAGS) -c $(srcdir)/$*.c
           有参数:
              .c.lo:
              $(LIBTOOL) --mode=compile $(CC) $(CFLAGS) -c $(srcdir)/$*.c
   ----------------------------------------------------------------------------------------------------------
          无参数:
             install: cjpeg djpeg jpegtran rdjpgcom wrjpgcom
          有参数: 
             install: cjpeg djpeg jpegtran rdjpgcom wrjpgcom install-lib
    -----------------------------------------------------------------------------------------------------------

step3:修改生成的Makefile文件:
       # The name of your C compiler:
       CC= gcc  该成  CC=arm-linux-gcc (根据你自己交叉编译器的位置修改)
       # library (.a) file creation command
       AR= ar rc 该成  AR=arm-linux-ar rc  (同上)
       # second step in .a creation (use "touch" if not needed)
       AR2= ranlib 该成  AR2=arm-linux-/ranlib (同上)

step4:sudo mkdir /home/jpeg_arm

           sudo mkdir /home/jpeg_arm/lib

          sudo mkdir /home/jpeg_arm/include

          sudo mkdir /home/jpeg_arm/man

          sudo mkdir /home/jpeg_arm/lib/man/man1

step5:#make
      #sudo make install
      这样JPEG库就交叉编译成功了,相应的库和头文件都在/home/jpeg_arm/lib和/home/jpeg_arm/include下了!

在编写应用程序在编译时记得加上 -ljpeg