如何在MSB处插入新位并忽略所有其他位

我发现了这个: add a new bit to the left of byte and discard right bit of byte 但是:

x = 0x80000000 | (x >> 1);

不会缝合我要找的东西。

union {
  unsigned char byte_variable;
  // a structure with 8 single bit bit-field objects, overlapping the union member "byte"
  struct {
                unsigned b0: 1;
                unsigned b1: 1;
                unsigned b2: 1;
                unsigned b3: 1;
                unsigned b4: 1;
                unsigned b5: 1;
                unsigned b6: 1;
                unsigned b7: 1;
  };
} byte_8;

显然设置有点像这样:

byte_8.b7 = 1;

如果你使用工会就不起作用。

如何在MSB处添加新位,并忽略或不更改变量中的所有其他位。

byte_8.byte_variable;