mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-06-28 03:29:35 +00:00
334 lines
9.0 KiB
JavaScript
334 lines
9.0 KiB
JavaScript
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var Assembler = function(spec) {
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var self = this;
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var ip = 0;
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var origin = 0;
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var linenum = 0;
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var symbols = {};
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var errors = [];
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var outwords = [];
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var asmlines = [];
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var fixups = [];
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var width = 8;
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var codelen = 0;
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var aborted = false;
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function rule2regex(rule, vars) {
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var s = rule.fmt;
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var varlist = [];
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rule.prefix = s.split(/\s+/)[0];
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s = s.replace(/\+/g, '\\+');
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s = s.replace(/\*/g, '\\*');
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s = s.replace(/\s+/g, '\\s+');
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s = s.replace(/\[/g, '\\[');
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s = s.replace(/\]/g, '\\]');
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s = s.replace(/\./g, '\\.');
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// TODO: more escapes?
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s = s.replace(/~\w+/g, function(varname) {
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varname = varname.substr(1);
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var v = vars[varname];
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varlist.push(varname);
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if (!v)
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throw Error("Could not find rule for ~" + varname);
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else if (v.toks)
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return '(\\w+)';
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else
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return '([0-9]+|[$][0-9a-f]+|\\w+)';
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});
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rule.re = new RegExp('^'+s+'$', 'i');
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rule.varlist = varlist;
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// TODO: check rule constraints
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return rule;
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}
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function preprocessRules() {
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if (spec.width)
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width = spec.width|0;
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for (var i=0; i<spec.rules.length; i++)
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rule2regex(spec.rules[i], spec.vars);
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}
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if (spec) preprocessRules();
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function warning(msg, line) {
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errors.push({msg:msg, line:line?line:linenum});
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}
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function fatal(msg, line) {
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warning(msg, line);
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aborted = true;
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}
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function fatalIf(msg, line) {
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if (msg) fatal(msg, line);
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}
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function hex(v, nd) {
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try {
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if (!nd) nd = 2;
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var s = v.toString(16).toUpperCase();
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while (s.length < nd)
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s = "0" + s;
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return s;
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} catch (e) {
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return v+"";
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}
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}
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function addBytes(result) {
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asmlines.push({
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line:linenum,
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offset:ip,
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nbits:result.nbits
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});
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var op = result.opcode;
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var nb = result.nbits/width;
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for (var i=0; i<nb; i++) {
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outwords[ip++ - origin] = (op >> (nb-1-i)*width) & ((1<<width)-1);
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}
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}
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function addWords(data) {
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asmlines.push({
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line:linenum,
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offset:ip,
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nbits:width*data.length
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});
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for (var i=0; i<data.length; i++) {
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outwords[ip++ - origin] = data[i] & ((1<<width)-1);
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}
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}
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function parseData(toks) {
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var data = [];
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for (var i=0; i<toks.length; i++) {
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data[i] = parseConst(toks[i]);
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}
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return data;
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}
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function stringToData(s) {
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var data = [];
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for (var i=0; i<s.length; i++) {
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data[i] = s.charCodeAt(i);
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}
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return data;
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}
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function alignIP(align) {
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if (align < 1 || align > codelen)
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fatal("Invalid alignment value");
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else
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ip = Math.floor((ip+align-1)/align)*align;
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}
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function parseConst(s, nbits) {
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// TODO: check bit length
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if (!s.length)
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return s;
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else if (s.startsWith("$"))
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return parseInt(s.substr(1), 16);
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else
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return parseInt(s);
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}
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self.buildInstruction = function(rule, m) {
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var opcode = 0;
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var oplen = 0;
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// iterate over each component of the rule output ("bits")
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for (var i=0; i<rule.bits.length; i++) {
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var b = rule.bits[i];
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var n,x;
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// is a string? then it's a bit constant
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// TODO
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if (b.length) {
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n = b.length;
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x = parseInt(b,2);
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} else {
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// it's an indexed variable, look up its variable
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var id = m[b+1];
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var v = spec.vars[rule.varlist[b]];
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if (!v) {
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return {error:"Could not find matching identifier for '" + m[0] + "'"};
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}
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n = v.bits;
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// is it an enumerated type? look up the index of its keyword
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if (v.toks) {
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x = v.toks.indexOf(id);
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if (x < 0)
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return null;
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} else {
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// otherwise, parse it as a constant
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x = parseConst(id, n);
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// is it a label? add fixup
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if (isNaN(x)) {
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fixups.push({sym:id, ofs:ip, bitlen:n, bitofs:oplen, line:linenum, iprel:!!v.iprel, ipofs:(v.ipofs+0)});
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x = 0;
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}
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}
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}
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var mask = (1<<n)-1;
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if ((x&mask) != x)
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return {error:"Value " + x + " does not fit in " + n + " bits"};
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opcode = (opcode << n) | x;
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oplen += n;
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}
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if (oplen == 0)
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warning("Opcode had zero length");
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else if (oplen > 32)
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warning("Opcodes > 32 bits not supported");
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else if ((oplen % width) != 0)
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warning("Opcode was not word-aligned (" + oplen + " bits)");
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return {opcode:opcode, nbits:oplen};
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}
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self.loadArch = function(arch) {
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if (self.loadJSON) {
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var json = self.loadJSON(arch + ".json");
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if (json && json.vars && json.rules) {
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spec = json;
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preprocessRules();
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} else {
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fatal("Could not load arch file '" + arch + ".json'");
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}
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}
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}
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function parseDirective(tokens) {
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var cmd = tokens[0].toLowerCase();
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if (cmd == '.define')
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symbols[tokens[1].toLowerCase()] = {value:tokens[2]};
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else if (cmd == '.org')
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ip = origin = parseInt(tokens[1]);
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else if (cmd == '.len')
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codelen = parseInt(tokens[1]);
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else if (cmd == '.width')
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width = parseInt(tokens[1]);
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else if (cmd == '.arch')
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fatalIf(self.loadArch(tokens[1]));
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else if (cmd == '.include')
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fatalIf(self.loadInclude(tokens[1]));
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else if (cmd == '.module')
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fatalIf(self.loadModule(tokens[1]));
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else if (cmd == '.data')
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addWords(parseData(tokens.slice(1)));
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else if (cmd == '.string')
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addWords(stringToData(tokens.slice(1).join(' ')));
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else if (cmd == '.align')
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alignIP(parseConst(tokens[1]));
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else
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warning("Unrecognized directive: " + tokens);
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}
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self.assemble = function(line) {
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linenum++;
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// remove comments
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line = line.replace(/[;].*/g, '').trim();
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// is it a directive?
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if (line[0] == '.') {
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var tokens = line.split(/\s+/);
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parseDirective(tokens);
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return;
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}
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// make it lowercase
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line = line.toLowerCase();
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// find labels
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line = line.replace(/(\w+):/, function(_label, label) {
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symbols[label] = {value:ip};
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return ''; // replace label with blank
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});
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line = line.trim();
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if (line == '')
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return; // empty line
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// look at each rule in order
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if (!spec) { fatal("Need to load .arch first"); return; }
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var lastError;
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for (var i=0; i<spec.rules.length; i++) {
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var rule = spec.rules[i];
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var m = rule.re.exec(line);
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if (m) {
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var result = self.buildInstruction(rule, m);
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if (result && result.nbits) {
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addBytes(result);
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return result;
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} else if (result && result.error) {
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lastError = result.error;
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}
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}
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}
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warning(lastError ? lastError : ("Could not decode instruction: " + line));
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}
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self.finish = function() {
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// apply fixups
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for (var i=0; i<fixups.length; i++) {
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var fix = fixups[i];
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var sym = symbols[fix.sym];
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if (sym) {
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var ofs = fix.ofs + Math.floor(fix.bitofs/width);
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var shift = fix.bitofs & (width-1);
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var mask = ((1<<fix.bitlen)-1);
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var value = parseConst(sym.value, fix.bitlen);
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if (fix.iprel)
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value -= fix.ofs + fix.ipofs;
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if (value > mask || value < -mask)
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warning("Symbol " + fix.sym + " (" + value + ") does not fit in " + fix.bitlen + " bits", fix.line);
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value &= mask;
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// TODO: check range
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// TODO: span multiple words?
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outwords[ofs - origin] ^= value; // TODO: << shift?
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} else {
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warning("Symbol '" + fix.sym + "' not found");
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}
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}
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// update asmlines
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for (var i=0; i<asmlines.length; i++) {
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var al = asmlines[i];
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al.insns = '';
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for (var j=0; j<al.nbits/width; j++) {
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var word = outwords[al.offset + j - origin];
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if (j>0) al.insns += ' ';
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al.insns += hex(word,width/4);
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}
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}
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while (outwords.length < codelen) {
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outwords.push(0);
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}
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fixups = [];
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return self.state();
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}
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self.assembleFile = function(text) {
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var lines = text.split(/\n/g);
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for (var i=0; i<lines.length && !aborted; i++) {
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try {
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self.assemble(lines[i]);
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} catch (e) {
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console.log(e);
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fatal("Exception during assembly: " + e);
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}
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}
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return self.finish();
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}
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self.state = function() {
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return {ip:ip, line:linenum, origin:origin, codelen:codelen,
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intermediate:{}, // TODO: listing, symbols?
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output:outwords, lines:asmlines, errors:errors, fixups:fixups};
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}
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}
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// Main
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if (typeof module !== 'undefined' && require.main === module) {
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var fs = require('fs');
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var stdinBuffer = fs.readFileSync(0);
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var code = stdinBuffer.toString();
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var asm = new Assembler();
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asm.loadJSON = function(filename) {
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return JSON.parse(fs.readFileSync(filename, 'utf8'));
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};
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asm.loadInclude = function(filename) {
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filename = filename.substr(1, filename.length-2); // remove quotes
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//return fs.readFileSync(filename, 'utf8');
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};
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asm.loadModule = function(top_module) {
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//TODO
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};
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var out = asm.assembleFile(code);
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console.log(out);
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}
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