ARM 指令集中的缩写(Rn, Rd, ...)是什么意思? [英] What do the abbriviations (Rn, Rd, ...) in the instruction set of ARM mean?

问题描述

最近我检查了 ARM Cortex-M3 处理器的指令集.例如:

ADD 、、

这些缩写到底是什么意思?我猜他们的意思是不同类型的地址，比如直接寻址、相对寻址等等.但究竟是什么?

谢谢！

解决方案

基础:

• Rd 是目的地，Rn 和 Rm 是来源.它们都是通用的整数寄存器；FP 将使用 Sd/Sn/Sm 或 Dd/Dn/Dm 单人或双人.
  ARM 语法将目标放在左侧，在只读源操作数之前.

有关更多信息，请参阅 Notlikethat 的答案.一些小的补充:

• t:在 这篇文章，一位 ARM 员工评论说t"可能意味着转移"而不是目标".

  由于 t 通常出现在 LDR 和 STR 等内存指令中，我理解这意味着转移到/从内存"，例如在 ARMARMv8-fa 上:

  LDR , [, (|){, {<金额>}}]STR <Xt>, [<Xn|SP>, (<Wm>|<Xm>){, <extend>{<金额>}}]

  其中 t 是内存读取和写入的源/目标.

  这在 STR 和 LDXR 指令寄存器的描述中也有进一步的建议:

  <块引用>

  是要传输的通用寄存器的 64 位名称，编码在Rt"中领域.

  但是 LDR 指令显示已加载":

  <块引用>

  是要加载的通用寄存器的 64 位名称，编码在Rt"中领域.

  这个术语特别有意义，因为 ARM 是 RISC-y，所以执行内存 IO 的指令相对较少，而且他们倾向于这样做(不像 x86 中常见的添加和存储到内存).

• t1 和 t2:它们用于一次加载/存储两个值的内存指令，例如ARMv8 LDP/STP:

  LDP 、、[]、#STP<Xt1>、<Xt2>、[<Xn|SP>、#<imm>]！

• n 和 m 只是数学中常用的整数变量/索引名称

• s:

  • STXR 指令将 Xt(如 STR)存储到内存中，但它还会获得第二个返回值(写入成功)到 Ws:

    STXR , , [{,#0}]

    所以大概选择 s 是因为它在 t 之前，就像 m 在 n 之前一样.

  • 某些 ARMv7/aarch32 指令可以在寄存器中进行移位，Rs 是该寄存器的名称，例如:

    ORR{}{} {,} , , <Rs>

    我无法轻松找到 aarch64.

• 如果有记录，C2 章关于 A64 指令描述"可能是提供信息的好位置，但它不在那里

recently i checked the Instruction Set for an ARM Cortex-M3 processor. For example:

ADD <Rd>, <Rn>, <Rm>

What do those abbriviations mean exactly? I guess they mean different kinds of addresses, like directely addressed, relatively addressed or so. But what exactly?

Thanks!

解决方案

Basics:

• Rd is the destination, Rn and Rm are sources. They're all general-purpose integer registers; FP would use Sd / Sn / Sm or Dd / Dn / Dm for single or double.
  ARM syntax puts the destination(s) on the left, before read-only source operands.

See Notlikethat's answer for more. Some small additions to that:

• t: in this post, an ARM employee comments that "t" might mean "transfer" instead of "target".

  Since t generally appears in memory instructions like LDR and STR, I understand that that means "transfer to/from memory", e.g. on ARMARMv8-fa:

  LDR <Xt>, [<Xn|SP>, (<Wm>|<Xm>){, <extend> {<amount>}}]
  STR <Xt>, [<Xn|SP>, (<Wm>|<Xm>){, <extend> {<amount>}}]
  

  where the t is the source/destination of memory reads and writes.

  This is also further suggested in the description of the STR and LDXR instruction registers:

  <Xt> Is the 64-bit name of the general-purpose register to be transferred, encoded in the "Rt" field.

  The LDR instruction however says "loaded":

  <Xt> Is the 64-bit name of the general-purpose register to be loaded, encoded in the "Rt" field.

  This terminology is especially meaningful because ARM is RISC-y and so there are relatively few instructions that do memory IO, and they tend to do just that (unlike say add and store to memory as is common in x86).

• t1 and t2: these are used for memory instructions that load/store two values at once, e.g. the ARMv8 LDP/STP:

  LDP <Xt1>, <Xt2>, [<Xn|SP>], #<imm>
  STP <Xt1>, <Xt2>, [<Xn|SP>, #<imm>]!
  

• n and m are just commonly used integer variable/index names in mathematics

• s:

  • the STXR instruction stores to memory fom Xt (like STR), but it also gets a second return value (did the write succeed) to Ws:

    STXR <Ws>, <Xt>, [<Xn|SP>{,#0}]
    

    so presumably s was chosen because it comes before t like m comes before n.

  • Some ARMv7/aarch32 instructions could take a shift in a register, and Rs is the name given to that register, e.g.:

    ORR{<c>}{<q>} {<Rd>,} <Rn>, <Rm>, <shift> <Rs> 
    

    I couldn't easily find aarch64 ones.

• if it were documented, "Chapter C2 About the A64 Instruction Descriptions" might have been a good location for the information, but it's not there

这篇关于ARM 指令集中的缩写(Rn, Rd, ...)是什么意思?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！