urbit-ob

commit df40a774b8aafcd94d3705f0fb627cee9d92f38c
parent 2d1518224fcbdd6180c2ae23fcaf65ae13cfde63
Author: Jared Tobin <jared@jtobin.io>
Date:   Thu, 27 Sep 2018 19:48:48 +1200

Add arbitrary-sized integer @p support.

Diffstat:
M
src/index.js
 | 
75
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------
M
test/core.test.js
 | 
22
++++++++++++++++++++++

2 files changed, 91 insertions(+), 6 deletions(-)
diff --git a/src/index.js b/src/index.js
@@ -2,7 +2,6 @@
  * Utility methods
  */
 
-// var bn = require('bignum')
 const bnjs = require('bn.js')
 const { reduce, isUndefined, isString, every, map } = require('lodash')
 
@@ -123,16 +122,17 @@ const arr2patp = a => reduce(a, (acc, syl, i) => isEven(i)
 
 
 const feen = pyn => {
-  const f = 4294967295
   if (pyn >= 0x10000 && pyn <= 0xFFFFFFFF) {
     const tmp = fice(pyn - 0x10000) + 0x10000
     return tmp
   }
   if (pyn >= 0x100000000 && pyn <= 0xffffffffffffffff) {
-    const pynBn = new bnjs(pyn)
-    const lo = pynBn.and(f)
-    const hi = pynBn.and('18446744069414584000')
-    return hi.or(feen(lo)).toNumber()
+    const f = new bnjs('4294967295')
+    const g = new bnjs('18446744069414584000')
+    const lo = pyn.and(f)
+    const hi = pyn.and(g)
+    let next = new bnjs(feen(lo))
+    return hi.or(next)
   }
   return pyn
 }
@@ -293,6 +293,67 @@ const murmur3 = (data, seed) => {
  *
  */
 
+const bex = (n) => {
+  const two = new bnjs(2)
+  return two.pow(n)
+}
+
+const rsh = (a, b, c) => {
+  const sub = bex(a).mul(b)
+  return c.div(bex(sub))
+}
+
+const met = (a, b, c = new bnjs(0)) => {
+  const zero = new bnjs(0)
+  const one = new bnjs(1)
+  return b.eq(zero)
+    ? c
+    : met(a, rsh(a, one, b), c.add(one))
+}
+
+const end = (a, b, c) => {
+  return c.mod(bex(bex(a).mul(b)))
+}
+
+const lsh = (a, b, c) => {
+  const sub = bex(a).mul(b)
+  return bex(sub).mul(c)
+}
+
+const patp = (n) => {
+  const zero = new bnjs(0)
+  const one = new bnjs(1)
+  const three = new bnjs(3)
+  const four = new bnjs(4)
+
+  let sxz = new bnjs(feen(n))
+  let dyy = met(four, sxz)
+
+  let loop = (tsxz, timp, trep) => {
+    let log = end(four, one, tsxz)
+    let pre = getPrefix(rsh(three, one, log))
+    let suf = getSuffix(end(three, one, log))
+    let etc =
+      (timp.mod(four)).eq(zero)
+        ? timp.eq(zero)
+          ? ''
+          : '--'
+        : '-'
+
+    let res = pre + suf + etc + trep
+
+    return timp.eq(dyy)
+      ? trep
+      : loop(rsh(four, one, tsxz), timp.add(one), res)
+  }
+
+  let dyx = met(three, sxz)
+
+  return '~' +
+    (dyx.lte(one)
+    ? getSuffix(sxz)
+    : loop(sxz, zero, ''))
+}
 
 
 // returns the class of a ship from it's name
@@ -438,6 +499,8 @@ module.exports = {
   toPlanetName: toPlanetName,
   isValidName: isValidName,
 
+  patp: patp,
+
   _add2patp: _add2patp,
   _getsuffix: getSuffix,
   _muk: muk,
diff --git a/test/core.test.js b/test/core.test.js
@@ -1,3 +1,4 @@
+const bnjs = require('bn.js');
 const ob = require('../src/index.js');
 
 
@@ -108,3 +109,24 @@ test('identifies binzod as a star from address', () => {
 test('identifies poldec-tonteg as a planet from address', () => {
   expect(ob.tierOfadd(9896704)).toBe('planet');
 });
+
+test('correctly encodes 0 as @p', () => {
+  let expected = '~zod';
+  expect(ob.patp('0')).toBe(expected);
+});
+
+test('correctly encodes 4294967295 as @p', () => {
+  let expected = '~dostec-risfen';
+  expect(ob.patp('4294967295')).toBe(expected);
+});
+
+test('correctly encodes 328256967394537077627 as @p', () => {
+  let expected = '~dozsyx--halrux-samlep-posmus-ranrux';
+  expect(ob.patp('328256967394537077627')).toBe(expected);
+});
+
+test('correctly encodes a big hex string as @p', () => {
+  let input = new bnjs('7468697320697320736f6d6520766572792068696768207175616c69747920656e74726f7079', 16);
+  let expected = '~divmes-davset-holdet--sallun-salpel-taswet-holtex--watmeb-tarlun-picdet-magmes--holter-dacruc-timdet-divtud--holwet-maldut-padpel-sivtud';
+  expect(ob.patp(input)).toBe(expected);
+});