The effective address is, under the hood, always split into a pair of 32-bit registers; the high-order register is optional and if it's not specified, it is treated as zero.
在这种情况下，有效地址总是分为两个32位的寄存器；高位寄存器是可选的，如果没有指定，就会被当作零进行处理。
Because channels are written using a register's preferred word-sized slot, the 64-bit address already has the high-order bits in the preferred slot.
由于信道是通过寄存器单字大小的首选槽写入的，所以64位地址在首选槽内已经有了高阶位。
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