# ARM Disassembler

The unit asm/armd decodes byte streams containing ARMv4 code into listings
where each line contains an operation.

Not all instructions are decoded yet, but the most important ones are supported.

The disassembler is used mainly through "dis ( a -- )", which spits a list of
"listingsz" (default 20) lines. To continue listing, use "disn ( -- )", which
continues where the last "dis" left off.

## Listing format

Each line in the listing has this format:

  addr cond mnemonic arguments rawbytes

Columns have a fixed width and are thus aligned with each other. The format of
the decoded instructions broadly follow "official" ARM assembler dialect.

While register numbers are in decimal form, all immediates and offsets are in
hexadecimal format, in their "rotated" final form. That is, the number being
shown is the result of the 8-bit immediate with its "rotate" field applied to
it.

LDR and STR have "!" and "p" flags. "!" is the "write back" flag and "p" is the
"post-inc" flag.

"B" and "BL" targets are displayed in absolute target address.

The "rawbytes" column is a dump of the raw bytes that were decoded on that line.

## Word labels

When listing a "B" or "BL", we check wether the target address is a word, that
is, a payload to a dictionary entry. We do so with the help of "?w>e"
[mem/dict]. If it is, we replace the "raw bytes" printing with the name of the
associated word.