C++内存布局相关问题 （android framework层 ）

Question

源码地址：http://androidxref.com/5.1.0_r1/xref/art/runtime/runtime.h#555

通过手段拿到Runtime指针runtime*后，想通过偏移量去拿heap_的指针，看网上有类似代码，heap的偏移量为188，求大神解答为何是188。

相关代码：

    JavaVMExt *vmExt = (JavaVMExt *) mirror_vm;
    char *runtime_ptr = (char *) vmExt->runtime;
    void **heap_pp = (void **) (runtime_ptr + 188);
    char *c_heap = (char *) (*heap_pp);

    char *min_free_offset = c_heap + 532;
    char *max_free_offset = min_free_offset + 4;

    size_t *min_free_ = (size_t *) min_free_offset;
    size_t *max_free_ = (size_t *) max_free_offset;
    *min_free_ = 1024 * 1024 * min;
    *max_free_ = 1024 * 1024 * max;