rebol[Title: "Tiny Asm 2" Date: 27-April-2007 File: %tiny_asm.r
    	Author: "Tim Wylie"	Purpose: "Assemble tiny code."]

tiny-asm: make object![
	make-row: func[rn[integer!] /opcode opc[string!] /asm-opcode aopc /operand oper /asm-operand aoper /byte b][
		make object![rownum: rn opcode: opc opcode-asm: aopc operand: oper operand-asm: aoper memory: b]]
	pad: func [value [string! number!] length [integer!] /fill char [char!] /locals field][
	    if not string? value [value: form value]
	    if none? char [char: #"0"]
	    insert/dup field: copy "" char length
	    change/part field head reverse value length? value
	    head reverse field
	]
	tiny-assembler: func[][
		if error? err: try[
			foreach line program-lines[
				if all[line/opcode (none? line/opcode-asm)][line/opcode-asm: (select opcode-table line/opcode)]
				if all[line/opcode-asm (none? line/opcode)][line/opcode: first back (find opcode-table line/opcode-asm)]
				if line/operand[
					line/operand-asm: (pad (select symbol-table line/operand) 3)
					if none? line/operand-asm[ numbers: charset[#"0" - #"9"]
						either (parse/all line/operand [some numbers])[
							line/operand-asm: (pad line/operand 3)][throw rejoin["Illegal operand line" line/rownum]]
				]
				either line/memory[line/memory: (pad to-string line/memory 5)
				][line/memory: rejoin[(pad line/opcode-asm 2) (pad to-integer line/operand-asm 3)]]
			]
		][print rejoin["Error assembling: " err/type err/code]]
	]
	tiny-parser: func[data [string!]][
		validchars: charset [#"0" - #"9" #"A" - #"Z" #"a" - #"z" #"_" #"#"]
		numbers: charset[#"0" - #"9"]	stringchars: complement charset[#"'"]
		whitespace: charset [#"^-" #"^/" " "]
		program-lines: copy [] line-counter: 0
		;verify syntax/build symbol table
		if error? try[
			foreach str parse/all data "^/"[
				opcode: none operand: none
				parse/all str [
					any[
						[copy opcode ["lda"|"ldi"|"ld"|"sti"|"st"|"add"|"sub"|"mul"|"div"|"bz"|"bp"|"bn"|"b"|"jsb"] some whitespace
							copy operand some validchars (append program-lines (make-row/opcode/operand/asm-opcode line-counter opcode operand (select opcode-table opcode)) line-counter: line-counter + 1)]
						|[["db"] some whitespace copy operand some numbers (append program-lines (make-row/byte line-counter operand) line-counter: line-counter + 1)]
						|[["ds"] some whitespace copy operand some numbers (loop to-integer operand [append program-lines (make-row line-counter) line-counter: line-counter + 1])]
						|[["dc"] any whitespace "'" copy operand some stringchars "'"(foreach let operand [append program-lines (make-row/byte line-counter to-integer let) line-counter: line-counter + 1])]
						|[copy opcode ["stop"|"in"|"out"|"push"|"pop"|"rsb"](append program-lines (make-row/opcode/asm-opcode line-counter opcode (select opcode-table opcode)) line-counter: line-counter + 1)]
						|[copy symbol some validchars ":"(repend symbol-table [symbol line-counter])]
						|[any whitespace ";" to end]
						|[some whitespace]
					]
				]
			]
		][print rejoin["Error parsing tiny code line: " line-counter] return false]
		return true
	]
	set 'assemble-tiny func[file [file!]][
		either[tiny-parser read file
			tiny-assembler
			write-asm file][print rejoin["Error reading file: " file]]
	]
	write-asm: func[file [file!]][
		if error? try[
			new-file: second split-path file
			new-file: join (copy/part new-file find new-file ".tny") ".tnc"
			if exists? new-file[delete new-file]
			foreach x program-lines[
				write/append new-file rejoin[(pad x/rownum 3) ", " (pad x/memory 5)newline]
			]
		][print rejoin["Error writing file: " new-file]
	]
	opcode-table: ["stop" 00 "ld" 01 "ldi" 02 "lda" 03 "st" 04 "sti" 05 "add" 06 "sub" 07 "mul" 08 "div" 09
		    "in" 10 "out" 11 "b" 12 "bp" 13 "bn" 14 "bz" 15 "jsb" 16 "rsb" 17 "push" 18 "pop" 19]
	symbol-table: ["printn" 900 "printc" 925 "inputn" 950 "inputc" 975]
	program-lines: none
]
either[system/script/args = none][print "FileName: " while[not exists? to-file filename: input]]
	[filename: system/scripts/args]
assemble-tiny to-file filename