lc3 LDR指令和存储的值 [英] lc3 LDR instruction and the value stored

问题描述

我不知道为什么After instruction LDR R3, R0, 2 is executed, the value stored in R3 is x370C.在此指令中2代表什么?它看起来不像是一个崇高的价值.我知道此时R0包含x370C.有人可以帮忙吗?非常感谢！

I can't figure out why After instruction "LDR R3, R0, 2" is executed, the value stored in R3 is x370C. what does 2 stands for in this instruction? It doesn't look like an immidiate value. I understand that R0 contains x370C at this point. Can someone please help? Many thanks!

.ORIG X3700
 LEA R0, A
 LDI R2, C 
 LDR R3, R0, 2 
 AND R1, R1, #0 
 IN
 ST R0, D 
 JSR  F 
 HALT
 F LD  R1, B
 ADD R1, R1, #1
 BRp F 
 RET

 A .FILL X1234
 B .FILL X370B
 C .FILL X370C
 D .BLKW 2
 E .STRINGZ "ABCD"
 G .FILL X1234
 .END

推荐答案

第二个参数是将要加载的基址的偏移量.

The second parameter is the offset of the base address that will be loaded.

我开始在这里拍一些照片并作了很好的解释，但是我发现了一个有趣的演讲视频，该视频比文字讲得更好，并且可以节省很多时间.

I started to take some pictures to post here and make a good explanation but I found an interesting lecture video that will explain much better than words and will save a lot of time.

LC3指令-LD，LDR，LDI，LEA

视频说明了LC3加载指令之间的差异，并着重说明了它们之间的差异.

The video is explaining the differences between the load instructions for the LC3, highlighting the differences between them.

在您的示例中:

您拥有自己的数据:

A .FILL X1234
B .FILL X370B
C .FILL X370C

运行代码:

LEA R0, A      -- R0 has the address of A
LDI R2, C      -- R2 has value of which address C has
LDR R3, R0, 2  -- R3 has the value of C 
               -- because R0 has the address of A + 2 positions = C

这篇关于lc3 LDR指令和存储的值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！