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collapseos/apps/shell/pgm.asm
Virgil Dupras 019d05f64c Make the shell a userspace app
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.
2019-11-15 15:37:49 -05:00

52 lines
1.4 KiB
NASM

; pgm - execute programs loaded from filesystem
;
; Implements a shell hook that searches the filesystem for a file with the same
; name as the cmd, loads that file in memory and executes it, sending the
; program a pointer to *unparsed* arguments in HL.
;
; We expect the loaded program to return a status code in A. 0 means success,
; non-zero means error. Programs should avoid having error code overlaps with
; the shell so that we know where the error comes from.
;
; *** Requirements ***
; fs
;
; *** Defines ***
; PGM_CODEADDR: Memory address where to place the code we load.
;
; *** Variables ***
.equ PGM_HANDLE PGM_RAMSTART
.equ PGM_RAMEND @+FS_HANDLE_SIZE
; Routine suitable to plug into SHELL_CMDHOOK. HL points to the full cmdline.
; which has been processed to replace the first ' ' with a null char.
pgmShellHook:
; (HL) is suitable for a direct fsFindFN call
call fsFindFN
jr nz, .noFile
; We have a file! Advance HL to args
xor a
call findchar
inc hl ; beginning of args
; Alright, ready to run!
jp .run
.noFile:
ld a, SHELL_ERR_IO_ERROR
ret
.run:
push hl ; unparsed args
ld ix, PGM_HANDLE
call fsOpen
ld hl, 0 ; addr that we read in file handle
ld de, PGM_CODEADDR ; addr in mem we write to
.loop:
call fsGetB ; we use Z at end of loop
ld (de), a ; Z preserved
inc hl ; Z preserved in 16-bit
inc de ; Z preserved in 16-bit
jr z, .loop
pop hl ; recall args
; ready to jump!
jp PGM_CODEADDR