soft reboot

makefile 中加上-o2 ，程序居然重启！！！！
过度优化的副作用！
过度优化导致指令乱序！

// 这些和错误处理有关，不用管
struct my_error_mgr {
    struct jpeg_error_mgr pub;  /* "public" fields */
 
    jmp_buf setjmp_buffer;  /* for return to caller */
};
 
typedef struct my_error_mgr * my_error_ptr;
 
METHODDEF(void) my_error_exit(j_common_ptr cinfo)
{
    my_error_ptr myerr = (my_error_ptr)cinfo->err;
    (*cinfo->err->output_message) (cinfo);
    longjmp(myerr->setjmp_buffer, 1);
}
 
// 读取图像的函数
// 我添加了一个参数，是我库里的zMatrix类对象，用于保存读取的图片数据
GLOBAL(int) read_JPEG_file(char * filename, z::Matrix8u & img)
{
    struct jpeg_decompress_struct cinfo;
    struct my_error_mgr jerr;
    FILE * infile;      
    JSAMPARRAY buffer;      
    int row_stride; 
 
    if ((infile = fopen(filename, "rb")) == NULL) {
        fprintf(stderr, "can't open %s\n", filename);
        return 0;
    }
    cinfo.err = jpeg_std_error(&jerr.pub);
    jerr.pub.error_exit = my_error_exit;
    if (setjmp(jerr.setjmp_buffer)) {
        jpeg_destroy_decompress(&cinfo);
        fclose(infile);
        return 0;
    }
    jpeg_create_decompress(&cinfo);
 
    jpeg_stdio_src(&cinfo, infile);
 
    // 这个函数获取了读取图片的信息，包括图片的高和宽
    (void)jpeg_read_header(&cinfo, TRUE);
    // 在这里添加你自己的代码，获取或用户到图像信息
    img.create(cinfo.image_height, cinfo.image_width, 3);
 
    (void)jpeg_start_decompress(&cinfo);
 
    row_stride = cinfo.output_width * cinfo.output_components;
    buffer = (*cinfo.mem->alloc_sarray)((j_common_ptr)&cinfo, JPOOL_IMAGE, row_stride, 1);
 
    while (cinfo.output_scanline < cinfo.output_height) {
        // 一行一行的读取
        (void)jpeg_read_scanlines(&cinfo, buffer, 1);
 
        // 在这里添加代码获取到图片的像素数据
        // buffer保存了读取的当前行的数据，保存顺序是RGB
        // output_scanline是已经读取过的行数
        for (int i = 0; i < img.cols; ++i) {
            img[cinfo.output_scanline - 1][i * 3 + 2] = buffer[0][i * 3 + 0];
            img[cinfo.output_scanline - 1][i * 3 + 1] = buffer[0][i * 3 + 1];
            img[cinfo.output_scanline - 1][i * 3 + 0] = buffer[0][i * 3 + 2];
        }
    }
 
    (void)jpeg_finish_decompress(&cinfo);
    jpeg_destroy_decompress(&cinfo);
    fclose(infile);
    return 1;
}
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