; yaglitch : Yet Another Glitch
; Copyright (C) 2018 Weber Yann
; 
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 3 of the License, or
; any later version.
; 
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.
; 
; You should have received a copy of the GNU General Public License
; along with this program.  If not, see <http://www.gnu.org/licenses/>.
;

[bits 64]

%include "sdl.asm"
%include "utils.asm"

%define STACK_SZ 256
%define MAX_FILE_SZ (16 * 17) ; 16 lines of 16 chars + newline chr
%define NL "!"

section .data

	op_ptrs:
		dq OP.t
		dq OP.put
		dq OP.drop
		dq OP.mul
		dq OP.div
		dq OP.add
		dq OP.sub
		dq OP.mod
		dq 0 ; syntax error
		dq OP.lshift
		dq OP.rshift
		dq OP.and
		dq OP.or
		dq OP.xor
		dq OP.not
		dq OP.dup
		dq OP.pick
		dq OP.swap
		dq OP.lt
		dq OP.gt
		dq OP.eq


	audiospec_wanted:
		dd 8000 ; freq
		dw AUDIO_U8 ; format
		db 1 ; channels
		db 0 ; silence
		dw 4096 ; samples
		dd 0 ; size
	dw 0 ; allign
		dq audio_cllbck
		dq 0 ; userdata
	

	def_str usage, "Usage : "
	def_str opts, {" FILE.glitch",0xA}
	def_str openerr, {'Error opening file : "', 0xA}
	def_str syntax_error, {"Syntax error", 0xA}
	def_str bigline_error, {"Line with more than 16 tokens !", 0xA}
	def_str nl_error, {"Character \n is not the last one", 0xA}
	def_str badop_error, {"Bad OP", 0xA}

	;
	; Old stuff for first oscillator
	;
	val: db 0
	dir: db 0

	dot: db "."
	nl: db 0xA


section .bss

	; glitch name (1st line) : len 16 + \0
	glitch_name: resb 17
	; program internal repr for stack machine
	; each token uses 2 words : 1st for the callback address 2nd for
	; optional value
	glitch_pgm: resq 16 * 16 * 2
	; stack machine ring buffer
	stack_buff: resd STACK_SZ
	; top of stack pointer
	tosp: resq 1
	; stack machine rgister
	t: resd 1
	; audiospec returned from SDL
	audiospec_recv: resb 32

section .text
global _start
_start:

	; checking args
	mov rcx, [rsp]
	cmp rcx, 2
	jne exit.badarg

	mov rax, 0x2 ; sys_open
	mov rdi, [rsp+16] ; argv[1]
	xor rsi, rsi ; no flags
	xor rdx, rdx ; O_RDONLY
	syscall
	cmp rax, 0
	jl exit.err_open
	push rax  ; source fd

	mov rax, 0xc ; brk
	xor rdi, rdi
	syscall
	push rax ; heap start

	mov rdi, rax
	add rdi, MAX_FILE_SZ ; new heap end
	mov rax, 0xc ; brk
	syscall

	pop rsi ; heap start
	mov r14, rsi
	xor rax, rax ; sys_read
	mov rdi, [rsp] ; source_fd
	mov rdx, MAX_FILE_SZ
	syscall
	cmp rax, 0
	jl exit.err_open
	mov r15, rax

	mov rax, 0x3 ; sys_close
	pop rdi ; source_fd
	syscall

	mov rbx, r15 ;read size
	mov rdi, r14 ; heap start
	add rdi, rbx ; heap end
	mov r15, rdi
	mov rax, 0xc ; brk
	syscall ; shrink heap to read size

	; init program space
	mov rdi, glitch_pgm
	xor rax, rax
	stosq
	stosq

	mov rsi, r14
	push rsi
	xor r13, r13
	xor rbx, rbx
parse:
	; go trhough file , with rsi current ptr, r15 file stop
	; r13 will contain updated lineno and rbx chr in current line
	; rdi store the destination pointer
	; parse glitch name
	mov rcx, 16
	mov rdi, glitch_name
	.name_loop:
		inc rbx
		lodsb
		test al, al ; EOF
		jz .no_nl
		cmp al, 0xA
		je .trailing_nl
		cmp al, "!" ; EOL
		je .name_end
		cmp al, "_"
		je .chrname
		cmp al, "0"
		jl exit.syntax_error
		cmp al, "9"
		jle .chrname
		cmp al, "a"
		jl exit.syntax_error
		cmp al, "z"
		jg exit.syntax_error
		.chrname:
			stosb
			loop .name_loop
	jmp exit.bigline
	.name_end:
		inc r13 ; lineno
		xor rbx, rbx
		xor al, al
		stosb

	; parsing tokens
	xor edx, edx ; 32bits numeric token value
	xor eax, eax
	xor r10, r10 ; numeric token flag (1 mean in numeric token)
	xor r11, r11 ; numeric token len
	mov rcx, r15
	sub rcx, r14
	mov rdi, glitch_pgm
	.parse_loop:
		inc rbx
		lodsb
		test al, al
		jz .no_nl
		cmp al, 0xA
		je .trailing_nl
		cmp al, "!" ; EOL
		je .next_line
		cmp al, "." ; token separator
		je .next_token
		cmp al, "0"
		jl exit.syntax_error
		cmp al, "9"
		jle .dec_token
		cmp al, "A"
		jl exit.syntax_error
		cmp al, "F"
		jle .hex_token
		jmp .op_match ; allowing loop near jump
		.end_op:
			stosq
			xor rax, rax
			stosq
			jmp .next_token

		.hex_token:
			sub al, "F"
			jmp .numeric_token
		.dec_token:
			sub al, "0"
		.numeric_token:
			cmp r11, 8
			je exit.syntax_error ; Numeric constant OF
			inc r11
			mov r10, 1
			shl edx, 8
			add edx, eax
		.next_token:
			;inc rbx ; chrno
		loop .parse_loop

		.next_line:
			inc r13
			xor rbx, rbx
		loop .parse_loop
	.trailing_nl:
		; check that NL is the last chr, else syntax error
		cmp rsi, r15
		jne exit.nl_not_last
		jmp .parse_end
	.op_match:
		; allow loop .parse_loop near jump
		cmp al, "a"
		jl exit.syntax_error
		cmp al, "u"
		jg exit.syntax_error
		; OP shortand matching
		; checking for previous numeric token to write
		test r10, r10
		jz .match_op
		push rax
		; add previous numeric token
		mov rax, OP.numeric
		stosq
		xor rax, rax
		xor r11, r11 ; numeric token length raz
		xchg rax, rdx
		shl rax, 32 ; shl to allow reading as dword ?
		stosq
		pop rax
		.match_op:
			sub al, "a"
			shl rax, 3 ; mul by 8 (size of ptr)
			add rax, op_ptrs
			mov rax, [rax]
			test rax, rax
			jz exit.bad_op
			jmp .end_op
	
	.no_nl: ; TODO : print warning
	; no NL at EOF

	.parse_end:
	
	; clean heap
	mov rax, 0xc
	pop rdi
	syscall
	
	; print glitch name
	mov rax, "Playing "
	push rax
	mov rax, 1
	mov rdi, 1
	mov rsi, rsp
	mov rdx, 8
	syscall
	pop rax

	mov rdi, glitch_name
	call strlen
	mov rdx, rax
	mov rax, 1
	mov rdi, 1
	mov rsi, glitch_name
	syscall

	mov rax, `\n`
	push rax
	mov rax, 1
	mov rdi, 1
	mov rsi, rsp
	mov rdx, 1
	syscall
	pop rax

	; init stack machine runtime
stack_init:
	
	mov rcx, STACK_SZ
	mov rdi, stack_buff
	xor rax, rax
	mov [t], eax
	.loop_buff_init:
		stosd
		loop .loop_buff_init
	mov al, 7 * 4
	mov [tosp], al

sdl_init:
	mov rdi, 0x0000FFFF
	call SDL_Init

	mov rdi, audiospec_wanted
	mov rsi, audiospec_recv
	call SDL_OpenAudio

	;mov rdi, 256
	;mov rsi, 255
	;mov rdx, 32
	;;mov rcx, SDL_SWSURFACE
	;xor rcx, rcx
	;call SDL_SetVideoMode

audio_start:
	;start audio
	xor rdi, rdi
	call SDL_PauseAudio

	mov rdi, 2000
	call SDL_Delay


exit:
	call SDL_Quit

	xor rdi, rdi
	mov rax, 0x3c
	syscall


	.err_open:
		mov rax, 1
		mov rdi, 2
		mov rsi, openerr
		mov rdx, openerr_len - 1
		syscall

		mov rdi, [rsp+16]
		push rdi
		call strlen

		mov rdx, rax
		mov rax, 1
		mov rdi, 2
		pop rsi
		syscall

		mov rax, 1
		mov rdi, 2
		mov rsi, openerr + openerr_len - 2
		mov rdx, 2
		syscall
	.badarg:
		mov rax, 1
		mov rdi, 2
		mov rsi, usage
		mov rdx, usage_len
		syscall

		mov rdi, [rsp+8]
		call strlen
		mov rdx, rax

		mov rax, 1
		mov rdi, 2
		mov rsi, [rsp+8]
		syscall

		mov rax, 1
		mov rdi, 2
		mov rsi, opts
		mov rdx, opts_len
		syscall
		mov rdi, 1
	.exit_err: ; with rdi error code
		mov rax, 0x3c ; exit
		syscall

	; expect : r13 lineno, rbx chr num in line
	; TODO: real error message
	.nl_not_last:
		mov rsi, nl_error
		mov rsi, nl_error_len
		push qword 3
		jmp exit.parse_error
	.syntax_error:
		mov rsi, syntax_error
		mov rdx, syntax_error_len
		push qword 2
		jmp exit.parse_error
	.bigline:
		mov rsi, bigline_error
		mov rdx, bigline_error_len
		push qword 2
		jmp exit.parse_error
	.bad_op:
		mov rsi, badop_error
		mov rdx, badop_error_len
		push qword 2
		jmp exit.parse_error
	.parse_error:
		; print error lineno & chrno
		push rsi ; source ptr
		push rdx
		push rbx ; chrno in line
		sub r14, rsi ; chr count
		push 14
		mov rdi, "chr:0x"
		mov rsi, 6
		call short_err
		pop rdi ; chr count
		mov rsi, 2
		call print_hnum
		mov rdi, ",line:0x"
		mov rsi, 8
		call short_err
		mov rdi, r13
		mov rsi, 2
		call print_hnum
		mov rdi, ",col:0x"
		mov rsi, 7
		call short_err
		pop rdi
		mov rsi, 2
		call print_hnum
		mov rdi, ` :\t`
		mov rsi, 3
		call short_err
		pop rdx
		pop rsi
		mov rax, 1
		mov rdi, 2
		syscall
		pop rdi
		jmp exit.exit_err

short_err:
	; rdi is the message (less than 8 chr)
	; rsi is message len
	push rdi
	mov rdx, rsi
	mov rsi, rsp
	mov rax, 1
	mov rdi, 1
	syscall
	pop rdi
	ret

strlen:
	; rdi containing str pointer
	; rax will contain strlen and rdi is unchanged
	mov rsi, rdi
	xor rdx, rdx
	pushf
	cld
	.loop:
		inc rdx
		lodsb
		mov cl, al
		test al, al
		jnz .loop
	dec rdx
	mov rax, rdx
	popf
	ret

print_hnum:
	; rdi : number to print
	; rsi : output fd
	pushf
	mov rax, rdi
	xor rcx, rcx
	push rcx ; using stack as buffer
	std
	lea rdi, [rsp + 8]
	.loop:
		test rax, rax
		jz .endloop
		inc rcx
		inc rcx
		push rax
		and al, 0x0F
		call .al2digit
		stosb
		mov rax, [rsp]
		shr al, 4
		call .al2digit
		stosb
		pop rax
		shr rax, 8
		jmp .loop
	.endloop:
	mov rax, 1
	xchg rdi, rsi
	inc rsi
	;mov rdi, rsi
	;mov rsi, rsp
	mov rdx, rcx
	syscall
	pop rax
	popf
	ret
	.al2digit:
		cmp al, 9
		jg .hex
		add al, "0"
		ret
		.hex:
		add al, "A" - 10
		ret

audio_cllbck:
	; rdi -> *userdata
	; rsi -> *stream
	; rdx -> stream_len
	mov rcx, rdx
	mov rdi, rsi
	.loop:
		push rcx
		push rdi
		call run_glitch
		pop rdi
		stosb
		pop rcx
		inc dword [t]
		loop .loop
	ret

run_glitch:
	; Run the glitch_pgm
	; return TOSP value in eax
	
	mov rsi, glitch_pgm
	.loop:
		lodsq
		test rax, rax
		jz .end_glitch
		push rax
		lodsq
		mov rdi, rax
		pop rax
		push rsi
		call rax
		pop rsi
		jmp .loop
	.end_glitch:
	xor rbx, rbx
	mov bl, [tosp]
	lea rdi, [stack_buff + rbx]
	mov eax, [rdi]
; DEBUG
	;push rax
	;xor rdi, rdi
	;mov rdi, rax
	;mov rsi, 1
	;call print_hnum
	;mov rax, " "
	;push rax
	;mov rax, 1
	;mov rdi, 1
	;mov rsi, rsp
	;mov rdx, 1
	;syscall
	;pop rax
	;pop rax
; /DEBUG
	ret

OP:
	.numeric:
		; rdi contain the number
		shr rdi, 32
	._push:
		; push rdi (edi) on stack_buff
		mov eax, edi
		xor rbx, rbx
		mov bl, [tosp]
		add bl, 4
		cmp bl, 8 * 4
		jl .go_push
		mov bl, 0
		.go_push:
			mov [tosp], bl
			lea rdi, [stack_buff+rbx]
			stosd
		ret

	.drop: ; drop just calls pop
	._pop:
		; pop eax from stack_buff
		xor rbx, rbx
		mov bl, [tosp]
		lea rsi, [stack_buff+rbx]
		xor rax, rax
		lodsd
		test bl, bl
		jz .pop_no_dec
		sub bl, 4
		jmp .pop_end
		.pop_no_dec:
			mov bl, 7 * 4
		.pop_end:
			mov [tosp], bl
		ret


	.t: ; push t on the stack
		mov edi, [t]
		call ._push
		ret

	.put:
		pushf
		cld
		xor rbx, rbx
		xor rax, rax
		mov bl, [tosp]
		lea rsi, [stack_buff+rbx]
		lodsd
		and eax, 0xFF
		inc eax
		mov edx, eax
		lodsd
		neg rdx
		lea rdi, [stack_buff + rdx]
		stosq
		call OP._pop
		popf
		ret
	.mul:
		call .prep_2arg
		mul ebx
		mov edi, eax
		call OP._push
		ret
	.div:
		call .prep_2arg
		test ebx, ebx
		jz .nodiv
		xor edx, edx
		div ebx
		jmp .divend
		.nodiv:
		xor eax, eax
		.divend:
		mov edi, eax
		call OP._push
		ret
	.add:
		call .prep_2arg
		add eax, ebx
		mov edi, eax
		call OP._push
		ret
	.sub:
		call .prep_2arg
		sub eax, ebx
		mov edi, eax
		call OP._push
		ret
	.mod:
		call .prep_2arg
		test ebx, ebx
		jz .nomod
		xor edx, edx
		div ebx
		jmp .endmod
		.nomod:
		xor edx, edx
		.endmod:
		mov edi, edx
		call OP._push
		ret
	.lshift:
		call OP._pop
		push rax
		call OP._pop
		pop rcx
		.lshift_loop:
			shl eax, 1
			loop .lshift_loop
		mov edi, eax
		call OP._push
		ret
	.rshift:
		call OP._pop
		push rax
		call OP._pop
		pop rcx
		.rshift_loop:
			shr eax, 1
			loop .rshift_loop
		mov edi, eax
		call OP._push
		ret
	.and:
		call .prep_2arg
		and eax, ebx
		mov edi, eax
		call OP._push
		ret
	.or:
		call .prep_2arg
		or eax, ebx
		mov edi, eax
		call OP._push
		ret
	.xor:
		call .prep_2arg
		xor eax, ebx
		mov edi, eax
		call OP._push
		ret
	.not:
		call OP._pop
		neg eax
		mov edi, eax
		call OP._push
		ret
	.dup:
		call OP._pop
		push rax
		mov edi, eax
		call OP._push
		pop rdi
		call OP._push
		ret
	.pick:
		call OP._pop
		inc eax
		and eax, 0xFF
		neg eax
		lea rsi, [stack_buff+eax]
		lodsd
		push rax
		call OP._pop
		pop rdi
		call OP._push
		ret


	.swap:
		call OP._pop
		push rax
		call OP._pop
		xchg rax, [rsp]
		mov edi, eax
		call OP._push
		pop rdi
		call OP._push
		ret
	.lt:
		call .prep_2arg
		xor rdi, rdi
		cmp eax, ebx
		jge .lt_false
		not rdi
		.lt_false:
		call OP._push
		ret
	.gt:
		call .prep_2arg
		xor rdi, rdi
		cmp eax, ebx
		jle .gt_false
		not rdi
		.gt_false:
		call OP._push
		ret
	.eq:
		call .prep_2arg
		xor rdi, rdi
		cmp eax, ebx
		jne .eq_false
		not rdi
		.eq_false:
		call OP._push
		ret

	.prep_2arg:
		; utils that pop both arguments V1 in eax, V2 in ebx
		call OP._pop
		push rax
		call OP._pop
		pop rbx
		ret