builtins/bigint: rewrite fromString

much better for large numbers

test262: 56.49% | 🧪 50259 | 🤠 28390 | ❌ 7231 (-1) | 💀 13701 (+1) | 🏗️ 32 | 💥 177 | ⏰ 11 | 📝 717

Author: CanadaHonk

compiler/builtins/bigint.ts

@@ -76,57 +76,59 @@ export const __Porffor_bigint_fromString = (n: string|bytestring): bigint => {
   const len: i32 = n.length;
 
   let negative: boolean = false;
-  let end: i32 = 0;
+  let offset: i32 = 0;
   if (n[0] === '-') {
     negative = true;
-    end = 1;
+    offset = 1;
   } else if (n[0] === '+') {
-    end = 1;
+    offset = 1;
   }
 
   // n -> digits (base 2^32) (most to least significant)
   // 4294967294 -> [ 4294967294 ]
   // 4294967295 -> [ 4294967295 ]
   // 4294967296 -> [ 1, 0 ]
   // 4294967297 -> [ 1, 1 ]
-  // 4294967298 -> [ 1, 2 ]
-  // 9007199254740992 -> [ 2097152 ]
+  // 9007199254740992 -> [ 2097152, 0 ]
   // 9007199254740993 -> [ 2097152, 1 ]
   // 9007199254740994 -> [ 2097152, 2 ]
-  // 9007199254740995 -> [ 2097152, 3 ]
 
-  let acc: number = 0;
-  let digits: i32[];
   const BASE: i32 = 0x100000000; // 2^32
+  const digits: i32[] = Porffor.allocate(); // todo: free later
+  digits.length = len - offset;
 
-  for (let i: i32 = end; i < len; i++) {
-    const char: i32 = n.charCodeAt(i);
+  let i: i32 = 0;
+  let acc: number = 0;
+  while (i < len) {
+    const char: i32 = n.charCodeAt(offset + i);
     const digit: i32 = char - 48;
-    if (digit < 0 || digit > 9) throw new SyntaxError('Invalid character in BigInt string');
-
-    if (acc == -1) {
-      let carry: i32 = digit;
-      for (let j: i32 = 0; j < digits.length; j++) {
-        const value: i32 = digits[j] * BASE + carry;
-        digits[j] = value % BASE;
-        carry = Math.trunc(value / BASE);
-      }
+    if (Porffor.fastOr(digit < 0, digit > 9)) throw new SyntaxError('Invalid character in BigInt string');
 
-      if (carry > 0) digits.push(carry);
-    } else {
-      acc = acc * 10 + digit;
-      if (acc >= BASE) {
-        digits = Porffor.allocate();
-        digits.length = 2;
-        digits[0] = Math.floor(acc / BASE);
-        digits[1] = acc % BASE;
-        acc = -1;
-      }
+    digits[i++] = digit;
+    acc = acc * 10 + digit;
+  }
+
+  if (acc < 0x8000000000000) {
+    // inline if small enough
+    return acc as bigint;
+  }
+
+  const result: i32[] = Porffor.allocate();
+  while (digits.length > 0) {
+    let carry: i32 = 0;
+    for (let j: i32 = 0; j < digits.length; j++) {
+      let value: i32 = carry * 10 + digits[j];
+      let quotient: i32 = Math.floor(value / BASE);
+      carry = value % BASE;
+
+      digits[j] = quotient;
     }
+
+    while (digits.length > 0 && digits[0] === 0) digits.shift();
+    if (carry !== 0 || digits.length > 0) result.unshift(carry);
   }
 
-  if (acc == -1) return __Porffor_bigint_fromDigits(negative, digits);
-  return (negative ? -acc : acc) as bigint;
+  return __Porffor_bigint_fromDigits(negative, result);
 };
 
 export const __Porffor_bigint_toString = (x: number, radix: any): string => {

compiler/builtins_precompiled.js

@@ -1,7 +1,7 @@
 {
   "name": "porffor",
   "description": "An ahead-of-time JavaScript compiler",
-  "version": "0.55.19",
+  "version": "0.55.20",
   "author": "Oliver Medhurst <[email protected]>",
   "license": "MIT",
   "scripts": {},

package.json

@@ -1,6 +1,6 @@
 #!/usr/bin/env node
 import fs from 'node:fs';
-globalThis.version = '0.55.19';
+globalThis.version = '0.55.20';
 
 // deno compat
 if (typeof process === 'undefined' && typeof Deno !== 'undefined') {