;NXOS shell
;----------
;Written by: Alberto Venturini (Alb‚) - 2001
;Email address: -albe-@libero.it

	org 0h

	cld
Main1:
;	mov si,offset Prompt	;shows the prompt
;	mov ah,01h
;	mov bl,07h
;	int 24h

	call ShowPrompt

	mov di,offset Command
	xor cx,cx

GetCommand:		;Get a string from the keyboard
	mov si,offset Command
	mov ah,07h
	int 25h
	dec si

ToUpCase:		;Turns everything upcase
	inc si
	mov al,ds:[si]
	cmp al,13
	je EndCommand
	cmp al,90
	jbe ToUpCase
	sub al,32
	mov ds:[si],al
	jmp ToUpCase

EndCommand:
	test cx,cx	;If only CR was pressed, just re-write the prompt
	jz Main1

	push cx
	mov di,offset Command

Test4Extension:			;tests if file extension is available
	mov al,es:[di]
	cmp al,'.'
	je ExtensionOk2
	inc di
	dec cx
	jnz Test4Extension

NoExtension:			;there's no extension...assume it's an internal
				;shell command

	pop cx

	mov di,offset Command

	mov cx,3
	mov si,offset ClsCmd
	push di
	rep cmpsb
	pop di
	je ShellCommand_Cls

	mov cx,4
	mov si,offset HelpCmd
	push di
	rep cmpsb
	pop di
	je ShellCommand_Help

	mov cx,8
	mov si,offset ShutdownCmd
	push di
	rep cmpsb
	pop di
	je ShellCommand_Shutdown

	mov cx,2
	mov si,offset CdCmd
	push di
	rep cmpsb
	pop di
	je ShellCommand_Cd

	mov ah,01h
	mov si,offset Error3
	mov bl,7
	int 24h

	jmp ClearCommandBuffer

ExtensionOk2:
	jmp ExtensionOk

ShellCommand_Cls:		;executes the "CLS" command
	mov ah,04h
	int 24h
	jmp ClearCommandBuffer

ShellCommand_Cd:
	mov si,offset CiaoDir
	mov ah,02h
	int 22h
	jmp ClearCommandBuffer

CiaoDir db 'CIAO    ',0

ShellCommand_Help:
	mov si,offset HelpTxt
	mov ah,01h
	mov bl,7
	int 24h
	jmp ClearCommandBuffer

ShellCommand_ShutDown:
	mov al,13
	mov ah,00h
	int 24h
	mov al,10
	int 24h
	xor ax,ax
	int 21h


ExtensionOk:	;there's the extension
	pop cx

StoreExtension:	;store the extension in a buffer ("Extension")
	push di
	inc di
	mov si,di
	mov di,offset Extension

	movsb
	movsb
	movsb

	mov di,offset Parameters	;store the parameters in a buffer
	mov cx,90
	inc si
	rep movsb

	pop di

	jmp ExecuteProgram

	push di
	sub di,offset Command

	cmp di,8
	jb StoreExtension2

	pop di		;file name must be <= 8
	mov di,offset Command
	add di,8
	jmp StoreExtension3

StoreExtension2:
	mov cx,8
	sub cx,di
	mov al,' '

	pop di

	rep stosb

StoreExtension3:
	mov si,offset Extension
	movsb
	movsb
	movsb

ExecuteProgram:
	mov di,offset Extension
	mov si,offset BinExtension

	mov cx,3

	push di
	rep cmpsb	;tests if the extension is "BIN"
	pop di
	je ExecuteBinProgram

	mov si,offset ComExtension
	mov cx,3

	push di
	rep cmpsb
	pop di
	je ExecuteComProgram

	mov si,offset ExeExtension
	mov cx,3
	push di
	rep cmpsb
	pop di
	je ExecuteExeProgram

	mov ah,01h
	mov si,offset Error2
	mov bl,7
	int 24h

	jmp Main1

ExecuteBinProgram:
	push es

	mov si,offset Command
	mov ah,00h
	int 20h
	test dx,dx
	jz FileNotFound
	mov bl,0
	mov ah,01h
	int 20h

	pop es

	jmp ClearCommandBuffer

ExecuteComProgram:
	push es

	mov si,offset Command
	mov bx,offset Parameters
	mov ah,07h
	int 20h
	test dx,dx
	jz FileNotFound
	mov bl,0
	mov ah,01h
	int 20h

	pop es

	jmp ClearCommandBuffer
ExecuteExeProgram:
	mov si,offset Command
	mov ah,08h
	int 20h
	jmp ClearCommandBuffer

FileNotFound:
	pop es
	mov si,offset Error1
	mov ah,01h
	mov bl,7
	int 24h

ClearCommandBuffer:
	mov di,offset Command
	mov al,' '
	mov cx,95

ClearCommandBuffer2:
	mov byte ptr cs:[di],al
	inc di
	loop ClearCommandBuffer2

	jmp Main1


;------------------------------------------------------------------------------

ShowPrompt:
	mov si,offset Prompt
	mov ah,01h
	mov bl,7
	int 24h

	mov al,'\'
	mov ah,00h
	int 24h

;	push ds
;	push es
;	push di

;	mov ah,05h	;get current dir name in ES:[DI]
;	int 22h
;
;	push es
;	pop ds
;	mov si,di
;	mov ah,01h
;	int 24h
;
;	pop di
;	pop es
;	pop ds

	ret


;------------------------------------------------------------------------------

Command db 100 dup (32)
Prompt	db 13,10,'Ready:',0
Error1	db 13,10,'File not found',13,10,0
Error2	db 13,10,'Invalid file name',13,10,0
Error3	db 13,10,'Invalid command',13,10,0
NextLine db 13,10,0
Extension db 3 dup (?)
BinExtension db 'BIN',0
ComExtension db 'COM',0
ExeExtension db 'EXE',0

ClsCmd	db 'CLS'
CdCmd	db 'CD'
HelpCmd	db 'HELP'
ShutdownCmd db 'SHUTDOWN'

;Help text

HelpTxt db 13,10,'NXOS shell',13,10
	db '-------------',13,10
	db 13,10
	db 'How to use this shell:',13,10
	db 'if you want to execute an external program, just type the',13,10
	db 'file name, with his extension.',13,10
	db 13,10
	db 'Available shell commands:',13,10
	db '  CLS: clears the screen',13,10
	db '  HELP: shows this screen',13,10
	db '  SHUTDOWN: reboots or shutdowns the system',13,10,0

Parameters:	;where to store the parameters