
; Public Domain

; test install command: install; xs; x uninstall
; test run command: s; .; .

%include "lmacros3.mac"
%include "eld.mac"
%include "eldcall.mac"
%include "elddata.mac"
%include "isvariab.mac"

	cpu 8086

	addsection RELOCATEDDATA, nobits vstart=_ELD_RELOC_VSTART
%xdefine SECTION_OF_relocateddata _CURRENT_SECTION
relocateddata:
%xdefine _EXPR_SECTION _CURRENT_SECTION

	addsection HEADER, start=0

	istruc ELD_HEADERX
at eldhxHeader
		; ELD executable header
	istruc ELD_HEADER
at eldhSignature,	db "ELD1"
			db 0,0,0
			db 26
at eldhCodeOffset,	dd CODEOFFSET
at eldhCodeImageLength,	dw code_size
at eldhCodeAllocLength,	dw 0
at eldhDataOffset,	dd DATAOFFSET
at eldhDataImageLength,	dw transient_data_size
at eldhDataAllocLength,	dw total_data_size - transient_data_size
at eldhCodeEntrypoint,	dw linker - code
at eldhReserved
at eldhExtensionSize,	dw header_extension_end - $$
	iend
at eldhxDescriptionOffset,	dd description
at eldhxHelpOffset,		dd DATAOFFSET + msg.help - datastart
header_extension_end:
	iend

description:		asciz "X commands and XARESULT variable."


	align 16, db 0

CODEOFFSET equ $ - $$
	addsection CODE, follows=HEADER vstart=_ELD_CODE_VSTART
%define CODEFIXUP - code + 0
code:
		; ELD instance header
	istruc ELD_INSTANCE
at eldiStartCode
at eldiEndCode
at eldiStartData
at eldiEndData
at eldiIdentifier,	fill 8, 32, db "X cmds"
	iend


DATAOFFSET equ CODEOFFSET + code_size
	addsection DATA, follows=CODE vstart=_ELD_DATA_VSTART
%define DATAFIXUP - datastart + 0
datastart:


	usesection CODE

command:
	jmp strict short .entry
.chain:
	extcall cmd3_not_ext, required	; must NOT be extcallcall
	times 10 - ($ - command) nop
.entry:
	push si
	cmp al, '?'
	jne .nothelp
	extcallcall skipcomma
	extcallcall uppercase
	cmp al, 'X'
	jne .nothelp
	extcallcall skipwhite
	extcallcall iseol?
	jne .nothelp
	call xhelp.eol_checked
	extcallcall cmd3

.nothelp:
	pop si
	dec si
	lodsb
	push si
	cmp al, '-'
	jne @F
	extcallcall skipcomma
@@:
	dec si
	lodsb
	extcallcall uppercase
	cmp al, 'X'
	je .ours
@@:
	pop si
	dec si
	lodsb
	jmp .chain

.ours:
	extcallcall skipcomma
	dec si
	mov dx, relocateddata
linkdatarelocation msg.uninstall
	extcallcall isstring?
	je uninstall
	lodsb
	call xx
	extcallcall cmd3

uninstall:
	pop ax
	lodsb
	extcallcall chkeol

	mov es, word [relocateddata]
linkdatarelocation extdssel
	extcallcall ispm
	jz @F
	mov es, word [relocateddata]
linkdatarelocation extseg
@@:
	push es
	pop ds
	xor bx, bx		; = 0 (no prior, modify ext_command_handler)
	mov di, command		; di -> us
internalcoderelocation
	mov si, word [ss:relocateddata]
linkdatarelocation ext_command_handler
				; si -> first
	test si, si		; none installed ?
	jz .error		; error -->

.loop:
	cmp di, si		; found ?
	je .bx			; yes, use bx -->
	mov bx, si		; bx -> prior handler
	lodsw			; skip entrypoint jmp strict short
	lodsb			; get first byte of chainer
	cmp al, 0E9h		; expecting jmp near ?
	jne .error		; no, error -->
	lodsw			; get rel16 displacement
	add si, ax		; -> next handler
	jmp .loop

.bx:
	test bx, bx		; any prior ?
	jnz .bxnz		; yes -->
	scasw			; skip entrypoint jmp strict short
	cmp byte [di], 0E8h	; is it a call to cmd3_not_ext ?
	jne @F			; no -->
				; yes, reset ext_command_handler to zero
.setbx:
	mov word [ss:relocateddata], bx
linkdatarelocation ext_command_handler
	jmp .done

@@:
	cmp byte [di], 0E9h	; validate
	jne .error		; failure -->
	inc di			; -> rel16 displacement
	mov bx, word [di]	; get displacement
	scasw			; -> after jmp near
	add bx, di		; -> next handler
	jmp .setbx		; set ext_command_handler to next

.bxnz:
	mov si, bx		; -> prior handler with us as downlink
	xchg di, si		; si -> ours, di -> prior
	cmpsw			; skip entrypoint jmp strict short
	movsb			; copy 0E8h/0E9h
	lodsw			; ax = near rel16 displacement
	add ax, si		; add in our base (= absolute offset)
	sub ax, di
	dec ax
	dec ax			; subtract new base (= relative displacement)
	stosw			; store new rel16 displacement
	movsw			; jmp strict short
	movsw			; linkcall target
	movsb			; trailer
.done:
	clropt [code + eldiFlags], eldifResident
internalcoderelocation -3	; mark block as free
	mov dx, msg.uninstall_done
internaldatarelocation
	mov di, [ss:nameheader_offset]
internaldatarelocation
	push ss
	pop es
	xor ax, ax
	stosw			; name header
	mov di, word [ss:structure_offset]
internaldatarelocation
	stosw			; ivName
	stosw			; ivFlags
	stosw			; ivAddress
@@:
	push ss
	pop ds
	extcallcall putsz
	extcallcall cmd3	; return

.error:
	mov dx, msg.uninstall_error
internaldatarelocation
	jmp @B


		; INP:	ax = array index (0-based)
		;	cx = offset of this handler (ip)
		;	dil = default size of variable (1..4)
		;	dih = length of variable name
		; CHG:	si, ax
		; OUT:	NC if valid,
		;	 bx -> var, di = 0 or di -> mask
		;	 cl = size of variable (1..4)
		;	 ch = length of variable name
varsetup:
	mov bx, xaresult
internaldatarelocation
	xor cx, cx		; NC, cx = 0
	xchg cx, di
	extcall var_ext_setup_done, required	; must NOT be extcallcall


%define relocated(address) relocateddata
%assign ELD 1
%assign _PM 1
%define lDEBUG_CODE CODE
%define lDEBUG_DATA_ENTRY DATA
TOLOWER		equ 32

%include "xxshared.asm"

error:
	extcall error

prnquit:
	extcallcall putsz
	extcallcall cmd3


	usesection DATA

%imacro dw_emserr 1-*.nolist
 %rep %0
	dw %1
  %ifnidni %1, 0
internaldatarelocation
  %endif
  %rotate 1
 %endrep
%endmacro
%include "xxmsg.asm"

crlf:		asciz 13,10


	usesection CODE

	eldcall_dump_callcall ELDCALL_CALLCALL_LIST

endinstalled equ ($ + CODEFIXUP + 15) & ~15


start:
	mov bx, es
	 push ss
	 pop es
	call skipcomma
	dec si
	mov dx, relocateddata
linkdatarelocation msg.install
	call isstring?
	je install
	lodsb
	extcall iseol?
	je .help
	call xx
	jmp .ret

.help:
	mov dx, msg.help
internaldatarelocation
	call putsz
.ret:
	call uninstall_oneshot
	xor ax, ax
	retf


uninstall_oneshot:
	testopt [ss:relocateddata], 1
linkdatarelocation options7, -3
	jnz @F

	mov ax, word [cs:code + eldiEndCode]
internalcoderelocation
	sub ax, word [cs:code + eldiStartCode]
internalcoderelocation
	sub word [relocateddata], ax
linkdatarelocation extseg_used

	mov ax, word [cs:code + eldiEndData]
internalcoderelocation
	sub ax, word [cs:code + eldiStartData]
internalcoderelocation
	sub word [relocateddata], ax
linkdatarelocation extdata_used
@@:
	retn


install:
	lodsb
	extcall chkeol

	houdini

	mov ax, relocateddata
linkdatarelocation ext_var_format
	cmp ax, 1
	jne .unknown
	mov ax, relocateddata
linkdatarelocation ext_var_size
	cmp ax, ISVARIABLESTRUC_size
	jne .unknown
	mov cx, relocateddata
linkdatarelocation ext_var_amount
	jcxz .unknown
	jmp @F

.unknown:
	mov dx, msg.unknown
internaldatarelocation
	extcall putsz
	xor ax, ax
	retf

@@:

	mov di, relocateddata
linkdatarelocation ext_var
	mov si, relocateddata
linkdatarelocation isvariable_morebyte_nameheaders.ext
.loop:
	cmp word [di], 0
	je .found
	add di, ISVARIABLESTRUC_size
	lodsw
	loop .loop

.nofree:
	mov dx, msg.nofree
internaldatarelocation
	extcall putsz
	xor ax, ax
	retf

.found:
	mov word [nameheader_offset], si
internaldatarelocation
	mov ax, word [header]
internaldatarelocation
	mov word [si], ax
	mov word [structure_offset], di
internaldatarelocation
	mov si, structure
internaldatarelocation
	mov cx, words(ISVARIABLESTRUC_size)
	rep movsw

	mov es, bx		; => ext seg (writable)
	mov ax, endresident - endinstalled
	sub word [es:code + eldiEndCode], ax
internalcoderelocation		; adjust size
	sub word [relocateddata], ax
linkdatarelocation extseg_used	; adjust size
	mov bx, word [relocateddata]
linkdatarelocation ext_command_handler
				; -> prior
	mov di, command		; -> our handler
internalcoderelocation
	test bx, bx		; installing as first ?
	jz .only_first		; yes, simple --> (leave as extcall cmd3_not_ext)
	scasw			; skip entrypoint jmp strict short
	mov al, 0E9h		; = jmp near opcode
	stosb			; store
	xchg ax, bx		; ax -> next handler
	sub ax, di
	dec ax
	dec ax			; ax = ax - (di + 2)
	stosw			; store our downlink as rel16 displacement

.only_first:
	setopt [es:code + eldiFlags], eldifResident
internalcoderelocation -3	; mark block as resident
	mov word [relocateddata], command
linkdatarelocation ext_command_handler, -4
internalcoderelocation		; -> our entrypoint

	testopt [relocateddata], 4
linkdatarelocation options7, -3
	jnz @F
	mov dx, msg.installed
internaldatarelocation
	call putsz
@@:
	xor ax, ax
	retf


	usesection DATA

transientdata_displacement_equate equ transientdata_displacement
%assign transientdata_displacement_assign transientdata_displacement_equate
transientdata_vstart equ _ELD_DATA_VSTART + transientdata_displacement_equate
	addsection TRANSIENTDATA, align=1 valign=1 \
		 follows=DATA vstart=transientdata_vstart, DATA
%define TRANSIENTDATAFIXUP - transientdatastart + transientdata_displacement_assign
transientdatastart:

%define IV_NAME_RELOCATION internaldatarelocation
%define IV_ADDRESS_RELOCATION internalcoderelocation
%define IV_SETUP_RELOCATION linkdatarelocation var_ext_setup
%assign IVS_ONEBYTE 0

; align 1-2+.nolist nop
    times (((2) - (($-$$ + transientdata_displacement_assign) % (2))) % (2)) db 0
structure:
isvariablestruc "XARESULT", 2, 0, varsetup, 0, 0, relocateddata

; align 1-2+.nolist nop
    times (((16) - (($-$$ + transientdata_displacement_assign) % (16))) % (16)) db 0
transient_data_size equ $ - $$ + transientdata_displacement_assign


	usesection DATA

isvariablestrings ISVARIABLESTRINGS


msg:
.uninstall_done:	asciz "X commands uninstalled. (Don't forget to use reclaim.eld)",13,10
.uninstall_error:	asciz "X commands unable to uninstall!",13,10
.xhelp:
%define MESSAGE_INLINE
%include "help/ems.asm"
		asciz

uinit_data: equ $

.help:		db "Install this ELD using the INSTALL keyword parameter.",13,10
		db 13,10
		db "Use X commands to run installed ELD.",13,10
		db "Use X? command to display help.",13,10
		db "Run as X UNINSTALL to uninstall this ELD.",13,10
		asciz
.installed:		asciz "X commands installed.",13,10
.nofree:		asciz "X commands cannot install, no ext variable free!",13,10
.unknown:		asciz "X commands cannot install, unknown ext variable format!",13,10


	align 2, db 0
header:
	dw IVS_MOREBYTE_NAMEHEADERS

transientdata_displacement: equ $ - datastart


	absolute uinit_data

	alignb 2
structure_offset:	resw 1
nameheader_offset:	resw 1

%if $ > msg.installed
 %error Variables overlap message
%endif

	alignb 16
uinit_data_end:
resident_data_end:

uinit_data_size equ uinit_data_end - datastart


%if uinit_data_size >= transient_data_size
 total_data_size equ uinit_data_size
%else
 total_data_size equ transient_data_size
%endif
%assign _DATA_SIZE total_data_size

	usesection CODE

%include "eldlink.asm"

	align 16
code_size equ $ - code
