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Allow for blank lines and comment-only lines in assembly code

This commit is contained in:
n loewen 2023-07-31 15:21:01 +01:00
parent b90300a257
commit afecab8ce3
1 changed files with 20 additions and 8 deletions
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28
sketches/assembler.js
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@ -22,27 +22,39 @@ function decodeMultipleInstructions(str) {
let lines = str.split(/\n/); // returns an array of lines let lines = str.split(/\n/); // returns an array of lines
let output = []; let output = [];
lines.forEach( (l) => { lines.forEach( (l) => {
let stripped = stripWhitespaceFromEnds(stripComments(l)); let decoded = decodeInstruction(l);
let decoded = decodeInstruction(stripped); if (decoded) {
output.push(decoded.op); output.push(decoded.op);
output.push(decoded.arg); output.push(decoded.arg);
}
}); });
return new Uint8Array(output); return new Uint8Array(output);
} }
/**
* @param {string} line - A line of assembly code
* @returns {(object|false)} Either {op: machineOp, arg: 0}, or false if the line was blank
*/
function decodeInstruction(line) { function decodeInstruction(line) {
let addressingMode = "direct"; // Must be "direct" or "indirect" line = stripWhitespaceFromEnds(stripComments(line));
op_arg_array = line.split(" "); let op_arg_array = line.split(" "); // split line into an array of [op, arg]
let opName = op_arg_array[0].toLowerCase(); let opName = op_arg_array[0].toLowerCase();
let addressingMode = 'direct'; // Must be "direct" or "indirect"
// Handle mnemonics without arguments (eg END) // Handle blank lines and mnemonics without arguments (eg END)
if (op_arg_array.length < 2) { // No argument if (op_arg_array.length < 2) { // No argument
// handle blank lines, or lines that just contain a comment:
if (line.length === 0) { return false; }
// handle mnemonics that aren't paired with an argument:
if (mnemonicsWithOptionalArgs.indexOf(opName) < 0) { if (mnemonicsWithOptionalArgs.indexOf(opName) < 0) {
throw error("Missing opcode"); console.error(`Missing opcode: ${line}`);
throw new Error("Missing opcode");
} }
let machineOp = mnemonics2opcodes[opName][addressingMode]; let machineOp = mnemonics2opcodes[opName][addressingMode];
return { op: machineOp, arg: 0 }; return { op: machineOp, arg: 0 };
} }
// Handle mnemonics with arguments (eg ADD $FF) // Handle mnemonics with arguments (eg ADD $FF)
let arg_str = op_arg_array[1]; let arg_str = op_arg_array[1];
if (arg_str.startsWith("(")) { if (arg_str.startsWith("(")) {