指针和索引在英特尔8086大会 [英] Pointers and Indexes in Intel 8086 Assembly

问题描述

我有一个指向数组的指针，DI

I have a pointer to an array, DI.

是否有可能去的价值指向两个DI和另一个指针？

Is it possible to go to the value pointed to by both DI and another pointer?

例如：

mov bl,1           
mov bh,10
inc [di+bl]
inc [di+bh]

和，与此相关的，是有一条线运code交换两个寄存器的值？ （在我而言，BX和BP？）

And, on a related note, is there a single line opcode to swap the values of two registers? (In my case, BX and BP?)

推荐答案

有关16位程序，唯一支持的寻址方式是：

For 16-bit programs, the only supported addressing forms are:

[BX+SI]
[BX+DI]
[BP+SI]
[BP+DI]
[SI]
[DI]
[BP]
[BX]

每个这些可能包括8位或16位的等速位移。

Each of these may include either an 8- or 16-bit constant displacement.

（来源：英特尔开发人员手册卷2A ，第38页）。

(Source: Intel Developer's Manual volume 2A, page 38)

与所提供的例子的问题是， BL 和 BH 八个位寄存器，不能用作基指针。但是，如果您设置 BX 来那么所需的值 INC [二+ BX] （用合适的尺寸说明符指针）是有效的。

The problem with the example provided is that bl and bh are eight-bit registers and cannot be used as the base pointer. However, if you set bx to the desired value then inc [di+bx] (with a suitable size specifier for the pointer) is valid.

至于交换寄存器的高低位，<一个href=\"http://stackoverflow.com/questions/3384346/pointers-and-indexes-in-intel-8086-assembly/3384358#3384358\">J-16 SDiZ年代建议 ROR BX，8 是罚款交换 BL 和 BH （IIRC和，它是这样做的最佳方式）。不过，如果你想交换的第0位（说） BL 与 BL 的第7位，则需要比这更逻辑。

As for swapping "the high and low bits of a register," J-16 SDiZ's suggestion of ror bx, 8 is fine for exchanging bl and bh (and IIRC, it is the optimal way to do so). However, if you want to exchange bit 0 of (say) bl with bit 7 of bl, you'll need more logic than that.

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