; jewelforth

;; MACROS {{{
%macro pspush 1
	lea r14, [r14-8]
	mov qword [r14], %1
%endmacro

%macro pspop 1
	mov %1, qword [r14]
	lea r14, [r14+8]
%endmacro

;;; dictionary macros {{{
%define mac_latest	0	; updated through defdict

%macro defdict 3 ; name asm-label flags
	%strlen slen %1
	global lfa_%2
	lfa_%2: dq mac_latest
		%define mac_latest lfa_%2
	ffa_%2:	db %3 ; FFA
	nfa_%2:	dw slen ; NFA
		db 0
		db %1
%endmacro

%macro defword 3
	defdict %1, %2, %3
	%2:
%endmacro

%macro defconst 4 ; ... value
	defdict %1, %2, %3
	%define %2 %4
	pspush qword %4
	ret
%endmacro

%macro defvar 4 ; ... default-value
	%2: dq %4
	defdict %1, %2, %3
	pspush qword %2
	ret
%endmacro

%assign smudge_mask	0x1
%assign immemdiate_mask	0x2

%assign false 0x0
%assign true 0xffffffffffffffff
;;; }}}

;; syscall
%assign	__NR_read	0
%assign	__NR_write	1
%assign	__NR_brk	12
%assign	__NR_exit	60
;; }}}

section .bss
wstack_b:	resq 2047
wstack:		resq 1

section .text
global _start
_start:
	; init
	mov r14, wstack ; point SP to top

	mov rdi, 0
	mov rax, __NR_exit
	syscall

defword "bye", bye, 0
	mov rdi, 0
	mov rax, __NR_exit
	syscall
	ret ; will not be reached

defword "@", fetch, 0
	pspop r11
	mov r12, qword [r11]
	pspush r12
	ret

defword "c@", cfetch, 0
	pspop r11
	xor r12, r12
	mov r12b, [r11]
	pspush r12
	ret

defword "!", store, 0
	pspop r11
	pspop r12
	mov qword [r11], r12
	ret

defword "c!", cstore, 0
	pspop r11
	pspop r12
	mov [r11], r12b
	ret

; stage 1 parser. very rudimentary, does not recognise numbers,
; only recognises newlines and spaces as whitespace.
; since it will only parse a little bit of the init file
; there won't be any error checking either.
defword "parse", parse, 0
	mov r13, qword [to_in]
	add r13, initfile
	mov r12b, byte [r13]

.wsloop: ; skip initial ws
	cmp r12b, 0x20
	je .wsloop_cont
	cmp r12b, 0x0a
	jne .wordloop_start
.wsloop_cont:
	inc r13
	mov r12b, byte [r13]
	jmp .wsloop

.wordloop_start:
	push r13 ; keep start address of this word for later
	mov r11, 1 ; W: word length count
.wordloop:
	cmp r12b, 0x20
	je .wordloop_end
	cmp r12b, 0x0a
	je .wordloop_end

	inc r11
	inc r13
	mov r12b, byte [r13]
	jmp .wordloop

.wordloop_end:
	sub r13, initfile
	mov qword [to_in], r13
	pop r13
	pspush r13 ; c-addr
	pspush r11 ; u
	ret

; probably fucked up and broken. have not tested any of this yet
defword "find", find, 0
	pspop r10 ; u
	pspop r11 ; c-addr
	mov r12, latest
	mov r13, qword [r12]
	mov r12, r13

.check_smudge:
	add r13, 8
	mov r9b, byte [r13]
	test r9b, smudge_mask
	jnz .no

.no_smudge:
	inc r13
	mov r9w, word [r13]
	cmp r9w, r10w
	jne .no
	mov rsi, r13
	add rsi, 2
	mov rdi, r11
	repz cmpsb
	jnz .no
	sub r13, 9
	pspush r13
	mov r13, true
	pspush r13
	ret

.no:
	mov r13, qword [r12]
	mov r12, r13
	cmp r13, 0 ; end of dictionary? fallthrough to notfound if so
	jne .check_smudge

	mov r13, false
	pspush r13
	ret

; stage 1 interpreter, just reads from initfile
defword "interpret", interpret, 0
	ret

defvar ">in", to_in, 0, initfile
defvar "latest", latest, 0, lfa_latest

initfile:
incbin "jefs.fs"
initlen equ $ - initfile
initfile_end: