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assembler.js
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assembler.js
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const { sequenceOf, whitespace, endOfInput, anyOfString, str, choice, char, possibly, many, many1, everyCharUntil } = require('arcsecond')
let currentLabel = 'default'
let currentPad = 256 // By default, write in main memory
const labels = new Map()
const macros = new Map()
const nonResolvedLiteralAbsoluteAddreses = []
const nonResolvedRelativeAddresses = []
const toHex = (i) => {
i = i.toString(16)
const result = i.length < 2 ? '0' + i : i
return result
}
const opCodes = ['BRK', 'INC', 'POP', 'DUP', 'NIP', 'SWP', 'OVR', 'ROT', 'EQU',
'NEQ', 'GTH', 'LTH', 'JMP', 'JCN', 'JSR', 'STH', 'LDZ', 'STZ',
'LDR', 'STR', 'LDA', 'STA', 'DEI', 'DEO', 'ADD', 'SUB', 'MUL',
'DIV', 'AND', 'ORA', 'EOR', 'SFT', 'LIT', 'LIT2']
const hexOpCodes = new Map()
opCodes.forEach((op, i) => {
if (op === 'LIT') {
hexOpCodes.set('LIT', '80')
} else if (op === 'LIT2') {
hexOpCodes.set('LIT2', 'a0')
} else {
hexOpCodes.set(op, toHex(i))
}
})
const LIT = '80'
const LIT2 = 'a0'
const UNRESOLVED_ADDRESS = '____'
const UNRESOLVED_RELATIVE_ADDRESS = '===='
const PAD = '0'
const hexadecimal = anyOfString('0123456789abdcef')
const allowedChars = anyOfString('0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_/><+*?!=&,\\".')
const opModifier = choice([char('k'), char('r'), char('2')])
const word = many1(allowedChars)
const tokens = []
tokens.comment = sequenceOf([char('('), everyCharUntil(char(')')), char(')')])
tokens.macro = sequenceOf([char('%'), everyCharUntil(whitespace), whitespace, char('{'), everyCharUntil(char('}')), char('}')])
tokens.zeroPageAddress = sequenceOf([char('.'), word])
tokens.absoluteAddress = sequenceOf([char(';'), word])
tokens.relativeAddress = sequenceOf([char(','), word])
tokens.pad = sequenceOf([char('|'), many(hexadecimal)])
tokens.relativePad = sequenceOf([char('$'), many1(hexadecimal)])
tokens.label = sequenceOf([char('@'), word])
tokens.sublabel = sequenceOf([char('&'), word])
tokens.literalChar = sequenceOf([char('\''), allowedChars])
tokens.literalNumber = sequenceOf([hexadecimal, hexadecimal, whitespace])
tokens.literalShort = sequenceOf([hexadecimal, hexadecimal, hexadecimal, hexadecimal, whitespace])
tokens.pushShort = sequenceOf([char('#'), hexadecimal, hexadecimal, hexadecimal, hexadecimal])
tokens.push = sequenceOf([char('#'), hexadecimal, hexadecimal])
tokens.ops = sequenceOf([choice(opCodes.map(e => str(e))), possibly(opModifier), possibly(opModifier), possibly(opModifier), whitespace])
tokens.string = sequenceOf([char('"'), many1(allowedChars)])
tokens.word = word
tokens.whitespace = whitespace
Object.keys(tokens).forEach(token => {
tokens[token] = tokens[token].map(e => ({ type: token, value: e }))
})
const parser = sequenceOf([many(choice(Object.keys(tokens).map(e => tokens[e]))), endOfInput])
const f = []
f.comment = (e) => {
// comment :)
}
f.label = (e, i, acc) => {
currentLabel = e.value[1].join('')
if (currentPad < 256) {
labels.set(e.value[1].join(''), toHex(currentPad))
} else {
labels.set(e.value[1].join(''), toHex(acc.length / 2))
}
}
f.zeroPageAddress = (e) => {
const label = e.value[1].join('')
return LIT + labels.get(label)
}
f.macro = (e) => {
macros.set(e.value[1], assemble(e.value[4]))
}
f.literalChar = (e) => {
return e.value[1].charCodeAt(0).toString(16)
}
f.literalNumber = (e) => {
return e.value[0] + e.value[1]
}
f.literalShort = (e) => {
return e.value[0] + e.value[1] + e.value[2] + e.value[3]
}
f.push = (e) => {
return LIT + e.value[1] + e.value[2]
}
f.pushShort = (e) => {
return LIT2 + e.value[1] + e.value[2] + e.value[3] + e.value[4]
}
f.ops = (e) => {
const k = e.value.filter(e => e === 'k')[0] ? 0x80 : 0x00
const r = e.value.filter(e => e === 'r')[0] ? 0x40 : 0x00
const s = e.value.filter(e => e === '2')[0] ? 0x20 : 0x00
return toHex(parseInt(hexOpCodes.get(e.value[0]), 16) + k + r + s)
}
f.word = (e) => {
const value = macros.get(e.value.join(''))
if (value) {
return value
} else {
throw new Error('Macro not found: ' + e.value.join(''))
}
}
f.pad = (e, i, acc) => {
const pad = parseInt(e.value[1].join(''), 16)
currentPad = pad
if (pad >= 256) {
return PAD.repeat((pad - 256) * 2)
}
}
f.relativePad = (e, i, acc) => {
const pad = parseInt(e.value[1].join(''), 16)
if (currentPad >= 256) {
currentPad += pad
return PAD.repeat(pad * 2)
} else {
currentPad += pad
}
}
f.absoluteAddress = (e, i, acc) => {
const label = e.value[1].join('')
if (labels.get(label) !== undefined) {
const pad = labels.get(label)
const page = toHex((Math.floor(parseInt(pad, 16) / 256) + 1))
const offset = toHex(((parseInt(pad, 16) % 256)))
return LIT2 + page + offset
} else {
nonResolvedLiteralAbsoluteAddreses.push(label)
return LIT2 + UNRESOLVED_ADDRESS
}
}
f.relativeAddress = (e, i, acc) => {
const isRelative = e.value[1].indexOf('&') !== -1
const completeLabel = isRelative ? currentLabel + '/' + e.value[1].join('').substring(1) : e.value[1].join('')
const label = labels.get(completeLabel)
if (label) {
const distance = label - (acc.length / 2) - 3
if (distance > 126) labelTooFarError(label)
return LIT + toHex(256 + (distance))
} else {
nonResolvedRelativeAddresses.push({ label: completeLabel, pos: acc.length / 2 })
return UNRESOLVED_RELATIVE_ADDRESS
}
}
f.sublabel = (e, i, acc) => {
const label = e.value[1].join('')
if (currentPad < 256) {
labels.set(currentLabel + '/' + label, toHex(currentPad))
} else {
labels.set(currentLabel + '/' + label, acc.length / 2)
}
}
f.string = (e, i, acc) => {
return e.value[1].map(e => e.charCodeAt(0).toString(16)).join('')
}
const assemble = (code) => {
code = code.replace(/\[|\]/g, ' ')
const context = parser.run(code)
if (context.isError) throw Error(context.error)
let ast = context.result[0] // Since result[1] is endOfInput
ast = ast.filter(e => e.type !== undefined)
const firstPass = ast.reduce((acc, e, i) => {
const next = f[e.type] !== undefined ? f[e.type](e, i, acc) : undefined
if (next) {
return acc + next
} else {
return acc
}
}, '')
return resolveAddresses(firstPass)
}
const resolveAddresses = (s) => {
nonResolvedLiteralAbsoluteAddreses.reverse()
while (s.indexOf(UNRESOLVED_ADDRESS) !== -1) {
const label = nonResolvedLiteralAbsoluteAddreses.pop()
const pad = labels.get(label)
const i = typeof pad === 'string' ? parseInt(pad, 16) : pad
const page = toHex((Math.floor(i / 256) + 1))
const offset = toHex(((i % 256)))
s = s.replace(UNRESOLVED_ADDRESS, page + offset)
}
nonResolvedRelativeAddresses.reverse()
while (s.indexOf(UNRESOLVED_RELATIVE_ADDRESS) !== -1) {
const label = nonResolvedRelativeAddresses.pop()
const labelPos = typeof labels.get(label.label) === 'string' ? parseInt(labels.get(label.label), 16) : labels.get(label.label)
if (labelPos === undefined) labelDoesNotExistError(label)
const distance = toHex(labelPos - (label.pos + 3))
if (parseInt(distance, 16) > 126) labelTooFarError(label)
s = s.replace(UNRESOLVED_RELATIVE_ADDRESS, LIT + distance)
}
return s
}
const labelTooFarError = (label) => {
throw new Error('Label: ' + label + 'too far.')
}
const labelDoesNotExistError = (label) => {
throw new Error('Label: ' + label + 'does not exist.')
}
module.exports = assemble