019d05f64c
That's my mega-commit you've all been waiting for. The code for the shell share more routines with userspace apps than with kernel units, because, well, its behavior is that of a userspace app, not a device driver. This created a weird situation with libraries and jump tables. Some routine belonging to the `kernel/` directory felt weird there. And then comes `apps/basic`, which will likely share even more code with the shell. I was seeing myself creating huge jump tables to reuse code from the shell. It didn't feel right. Moreover, we'll probably want basic-like apps to optionnally replace the shell. So here I am with this huge change in the project structure. I didn't test all recipes on hardware yet, I will do later. I might have broken some... But now, the structure feels better and the line between what belongs to `kernel` and what belongs to `apps` feels clearer. |
||
|---|---|---|
| .. | ||
| buf.asm | ||
| cmd.asm | ||
| glue.asm | ||
| io.asm | ||
| main.asm | ||
| README.md | ||
ed - line editor
Collapse OS's ed is modeled after UNIX's ed (let's call it Ued). The goal
is to have an editor that is tight on resources and that doesn't require
ncurses-like screen management.
In general, we try to follow Ued's conventions and the "Usage" section is
mostly a repeat of Ued's man page.
Differences
There are a couple of differences with Ued that are intentional. Differences
not listed here are either bugs or simply aren't implemented yet.
- Always has a prompt,
:. - No size printing on load
- Initial line is the first one
- Line input is for one line at once. Less scriptable for
Ued, but we can't scriptedin Collapse OS anyway... - For the sake of code simplicity, some commands that make no sense are
accepted. For example,
1,2ais the same as2a.
Usage
ed is invoked from the shell with a single argument: the name of the file to
edit. If the file doesn't exist, ed errors out. If it exists, a prompt is
shown.
In normal mode, ed waits for a command and executes it. If the command is
invalid, a line with ? is printed and ed goes back to waiting for a command.
A command can be invalid because it is unknown, malformed or if its address range is out of bounds.
Commands
(addrs)p: Print lines specified inaddrsrange. This is the default command. If only(addrs)is specified, it has the same effect.(addrs)d: Delete lines specified inaddrsrange.(addr)a: Appends a line afteraddr.(addr)i: Insert a line beforeaddr.w: write to file. For now,qis implied inw.q: quitedwithout writing to file.
Current line
The current line is central to ed. Address ranges can be expressed relatively
to it and makes the app much more usable. The current line starts at 1 and
every command changes the current line to the last line that the command
affects. For example, 42p changes the current line to 42, 3,7d, to 7.
Addresses
An "address" is a line number. The first line is 1. An address range is a
start line and a stop line, expressed as start,stop. For example, 2,4 refer
to lines 2, 3 and 4.
When expressing ranges, stop can be omitted. It will then have the same value
as start. 42 is equivalent to 42,42.
Addresses can be expressed relatively to the current line with + and -.
+3 means "current line + 3", -5, +2 means "address range starting at 5
lines before current line and ending 2 lines after it`.
+ alone means +1, - means -1.
. means current line. It can usually be omitted. p is the same as .p.
$ means the last line of the buffer.