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-[The Readme](Readme.md) describes SubX notation with some details hidden
-behind _syntax sugar_ -- local rewrite rules that make programming in SubX
-less error-prone. However, much low-level SubX (before the syntax sugar is
-implemented) is written without syntax sugar. This document describes some
-details of the syntax sugar: how the reg/mem operand is translated into
-arguments.
-
-## How x86 instructions compute operands
-
-The [Intel processor manual](http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf)
-is the final source of truth on the x86 instruction set, but it can be
-forbidding to make sense of, so here's a quick orientation. You will need
-familiarity with binary numbers, and maybe a few other things. Email [me](mailto:mu@akkartik.com)
-any time if something isn't clear. I love explaining this stuff for as long as
-it takes. The bad news is that it takes some getting used to. The good news is
-that internalizing the next 500 words will give you a significantly deeper
-understanding of your computer.
-
-The reg/mem operand can be specified by 1-7 arguments, each ranging in size
-from 2 bits to 4 bytes. The key argument that's always present for reg/mem
-operands is `/mod`, the _addressing mode_. This is a 2-bit argument that can
-take 4 possible values, and it determines what other arguments are required,
-and how to interpret them.
-
-* If `/mod` is `3`: the operand is in the register described by the 3-bit
-  `/rm32` argument.
-
-* If `/mod` is `0`: the operand is in the address provided in the register
-  described by `/rm32`. That's `*rm32` in C syntax.
-
-* If `/mod` is `1`: the operand is in the address provided by adding the
-  register in `/rm32` with the (1-byte) displacement. That's `*(rm32 + /disp8)`
-  in C syntax.
-
-* If `/mod` is `2`: the operand is in the address provided by adding the
-  register in `/rm32` with the (4-byte) displacement. That's `*(/rm32 +
-  /disp32)` in C syntax.
-
-In the last three cases, one exception occurs when the `/rm32` argument
-contains `4`. Rather than encoding register `esp`, it means the address is
-provided by three _whole new_ arguments (`/base`, `/index` and `/scale`) in a
-_totally_ different way (where `<<` is the left-shift operator):
-
-  ```
-  reg/mem = *(base + (index << scale))
-  ```
-
-(There are a couple more exceptions ☹; see [Table 2-2](modrm.pdf) and [Table 2-3](sib.pdf)
-of the Intel manual for the complete story.)
-
-Phew, that was a lot to take in. Some examples to work through as you reread
-and digest it:
-
-1. To read directly from the `eax` register, `/mod` must be `3` (direct mode),
-   and `/rm32` must be `0`. There must be no `/base`, `/index` or `/scale`
-   arguments.
-
-1. To read from `*eax` (in C syntax), `/mod` must be `0` (indirect mode), and
-   the `/rm32` argument must be `0`. There must be no `/base`, `/index` or
-   `/scale` arguments (Intel calls the trio the 'SIB byte'.).
-
-1. To read from `*(eax+4)`, `/mod` must be `1` (indirect + disp8 mode),
-   `/rm32` must be `0`, there must be no SIB byte, and there must be a single
-   displacement byte containing `4`.
-
-1. To read from `*(eax+ecx+4)`, one approach would be to set `/mod` to `1` as
-   above, `/rm32` to `4` (SIB byte next), `/base` to `0`, `/index` to `1`
-   (`ecx`) and a single displacement byte to `4`. (What should the `scale` bits
-   be? Can you think of another approach?)
-
-1. To read from `*(eax+ecx+1000)`, one approach would be:
-   - `/mod`: `2` (indirect + disp32)
-   - `/rm32`: `4` (`/base`, `/index` and `/scale` arguments required)
-   - `/base`: `0` (eax)
-   - `/index`: `1` (ecx)
-   - `/disp32`: 4 bytes containing `1000`
-
-## Putting it all together
-
-Here's an example showing these arguments at work:
-
-<img alt='apps/ex3.subx' src='html/ex3.png'>
-
-This program sums the first 10 natural numbers. By convention I use horizontal
-tabstops to help read instructions, dots to help follow the long lines,
-comments before groups of instructions to describe their high-level purpose,
-and comments at the end of complex instructions to state the low-level
-operation they perform. Numbers are always in hexadecimal (base 16) and must
-start with a digit ('0'..'9'); use the '0x' prefix when a number starts with a
-letter ('a'..'f'). I tend to also include it as a reminder when numbers look
-like decimal numbers.
-
----
-
-I recommend you order arguments consistently in your programs. SubX allows
-arguments in any order, but only because that's simplest to explain/implement.
-Switching order from instruction to instruction is likely to add to the
-reader's burden. Here's the order I've been using after opcodes:
-
-```
-        |<--------- reg/mem --------->|        |<- reg/mem? ->|
-/subop  /mod /rm32  /base /index /scale  /r32   /displacement   /immediate
-```
-
----
-
-Try running this example now:
-
-```sh
-$ ./bootstrap translate init.linux apps/ex3.subx -o apps/ex3
-$ ./bootstrap run apps/ex3
-$ echo $?
-55
-```
-
-If you're on Linux you can also run it natively:
-
-```sh
-$ ./apps/ex3
-$ echo $?
-55
-```
-
-These details should now be enough information for reading and modifying
-low-level SubX programs.