Convert to BN

.gitignore

@@ -2,3 +2,4 @@
 coverage
 .nyc_output
 node_modules
+.vscode/

accumulative.js

@@ -1,38 +1,48 @@
 var utils = require('./utils')
+var ext = require('./bn-extensions')
 
 // add inputs until we reach or surpass the target value (or deplete)
 // worst-case: O(n)
 module.exports = function accumulative (utxos, outputs, feeRate) {
-  if (!isFinite(utils.uintOrNaN(feeRate))) return {}
+  if (!isFinite(utils.bnOrNaN(feeRate))) return {}
   var bytesAccum = utils.transactionBytes([], outputs)
 
-  var inAccum = 0
+  var inAccum = ext.BN_ZERO
   var inputs = []
   var outAccum = utils.sumOrNaN(outputs)
 
   for (var i = 0; i < utxos.length; ++i) {
     var utxo = utxos[i]
     var utxoBytes = utils.inputBytes(utxo)
-    var utxoFee = feeRate * utxoBytes
-    var utxoValue = utils.uintOrNaN(utxo.value)
+    var utxoFee = ext.mul(feeRate, utxoBytes)
+    var utxoValue = utils.bnOrNaN(utxo.value)
 
     // skip detrimental input
-    if (utxoFee > utxo.value) {
-      if (i === utxos.length - 1) return { fee: feeRate * (bytesAccum + utxoBytes) }
+    var feeIsMoreThanValue = ext.gt(utxoFee, utxoValue)
+    // utxoFee > utxoValue
+    if (feeIsMoreThanValue) {
+      if (i === utxos.length - 1) {
+        var bytesSum = ext.add(bytesAccum, utxoBytes)
+        return {
+          fee: ext.mul(feeRate, bytesSum)
+        }
+      }
       continue
     }
 
-    bytesAccum += utxoBytes
-    inAccum += utxoValue
+    bytesAccum = ext.add(bytesAccum, utxoBytes)
+    inAccum = ext.add(inAccum, utxoValue)
     inputs.push(utxo)
 
-    var fee = feeRate * bytesAccum
+    var fee = ext.mul(feeRate, bytesAccum)
 
     // go again?
-    if (inAccum < outAccum + fee) continue
+    if (ext.lt(inAccum, ext.add(outAccum, fee))) continue
 
     return utils.finalize(inputs, outputs, feeRate)
   }
 
-  return { fee: feeRate * bytesAccum }
+  return {
+    fee: feeRate.mul(bytesAccum)
+  }
 }

blackjack.js

@@ -1,35 +1,42 @@
 var utils = require('./utils')
+var ext = require('./bn-extensions')
 
 // only add inputs if they don't bust the target value (aka, exact match)
 // worst-case: O(n)
 module.exports = function blackjack (utxos, outputs, feeRate) {
-  if (!isFinite(utils.uintOrNaN(feeRate))) return {}
+  if (!isFinite(utils.bnOrNaN(feeRate))) return {}
 
   var bytesAccum = utils.transactionBytes([], outputs)
 
-  var inAccum = 0
+  var inAccum = ext.BN_ZERO
   var inputs = []
   var outAccum = utils.sumOrNaN(outputs)
   var threshold = utils.dustThreshold({}, feeRate)
 
   for (var i = 0; i < utxos.length; ++i) {
     var input = utxos[i]
     var inputBytes = utils.inputBytes(input)
-    var fee = feeRate * (bytesAccum + inputBytes)
-    var inputValue = utils.uintOrNaN(input.value)
+    var fee = ext.mul(feeRate, ext.add(bytesAccum, inputBytes))
+    var inputValue = utils.bnOrNaN(input.value)
 
     // would it waste value?
-    if ((inAccum + inputValue) > (outAccum + fee + threshold)) continue
+    var totalInputs = ext.add(inAccum, inputValue)
+    var outputsAndFee = ext.add(outAccum, fee)
+    var totalOutputs = ext.add(outputsAndFee, threshold)
+    var inputsAreGreaterThanOutputs = ext.gt(totalInputs, totalOutputs)
 
-    bytesAccum += inputBytes
-    inAccum += inputValue
+    if (inputsAreGreaterThanOutputs) continue
+
+    bytesAccum = ext.add(bytesAccum, inputBytes)
+    inAccum = ext.add(inAccum, inputValue)
     inputs.push(input)
 
     // go again?
-    if (inAccum < outAccum + fee) continue
+    if (ext.lt(inAccum, outputsAndFee)) continue
 
     return utils.finalize(inputs, outputs, feeRate)
   }
-
-  return { fee: feeRate * bytesAccum }
+  return {
+    fee: feeRate.mul(bytesAccum)
+  }
 }

bn-extensions.js

@@ -0,0 +1,74 @@
+var BN = require('bn.js')
+
+var BN_ZERO = new BN(0)
+var BN_ONE = new BN(1)
+
+function mul (multiplicand, multiplier) {
+  if (!BN.isBN(multiplicand) || !BN.isBN(multiplier)) return NaN
+
+  return multiplicand.mul(multiplier)
+}
+
+function div (dividend, divisor) {
+  if (!BN.isBN(dividend) || !BN.isBN(divisor)) return NaN
+  if (divisor.cmp(BN_ZERO) === 0) return Infinity
+
+  return dividend.div(divisor)
+}
+
+function add (arg1, arg2, arg3) {
+  // Add two items
+  if (!BN.isBN(arg1) || !BN.isBN(arg2)) return NaN
+  if (typeof arg3 === 'undefined') return arg1.add(arg2)
+
+  // Add three items
+  if (!BN.isBN(arg3)) return NaN
+  return arg1.add(arg2).add(arg3)
+}
+
+function sub (arg1, arg2, arg3) {
+  // Subtract two items
+  if (!BN.isBN(arg1) || !BN.isBN(arg2)) return NaN
+  if (typeof arg3 === 'undefined') return arg1.sub(arg2)
+
+  // Subtract three items
+  if (!BN.isBN(arg3)) return NaN
+  return arg1.sub(arg2).sub(arg3)
+}
+
+function shrn (argument, shiftBy) {
+  if (!BN.isBN(argument)) return NaN
+  if (BN.isBN(shiftBy)) shiftBy = shiftBy.toNumber()
+  if (typeof shiftBy !== 'number') return NaN
+
+  return argument.shrn(shiftBy)
+}
+
+function isZero (argument) {
+  if (!BN.isBN(argument)) return false
+  if (argument.cmp(BN_ZERO) === 0) return true
+  return false
+}
+
+function lt (subject, argument) {
+  if (!BN.isBN(argument) || !BN.isBN(subject)) return false
+  return subject.lt(argument)
+}
+
+function gt (subject, argument) {
+  if (!BN.isBN(argument) || !BN.isBN(subject)) return false
+  return subject.gt(argument)
+}
+
+module.exports = {
+  mul: mul,
+  div: div,
+  add: add,
+  sub: sub,
+  shrn: shrn,
+  isZero: isZero,
+  lt: lt,
+  gt: gt,
+  BN_ZERO: BN_ZERO,
+  BN_ONE: BN_ONE
+}

break.js

@@ -1,32 +1,39 @@
 var utils = require('./utils')
+var ext = require('./bn-extensions')
 
 // break utxos into the maximum number of 'output' possible
 module.exports = function broken (utxos, output, feeRate) {
-  if (!isFinite(utils.uintOrNaN(feeRate))) return {}
+  if (!isFinite(utils.bnOrNaN(feeRate))) return {}
 
   var bytesAccum = utils.transactionBytes(utxos, [])
-  var value = utils.uintOrNaN(output.value)
+  var value = utils.bnOrNaN(output.value)
   var inAccum = utils.sumOrNaN(utxos)
+
   if (!isFinite(value) ||
-      !isFinite(inAccum)) return { fee: feeRate * bytesAccum }
+      !isFinite(inAccum)) return { fee: feeRate.mul(bytesAccum) }
 
   var outputBytes = utils.outputBytes(output)
-  var outAccum = 0
+  var outAccum = ext.BN_ZERO
   var outputs = []
 
   while (true) {
-    var fee = feeRate * (bytesAccum + outputBytes)
+    // feeRate * (bytesAccum + outputBytes)
+    var fee = ext.mul(feeRate, ext.add(bytesAccum, outputBytes))
 
     // did we bust?
-    if (inAccum < (outAccum + fee + value)) {
+    if (ext.lt(inAccum, ext.add(outAccum, fee, value))) {
+      var isZero = ext.isZero(outAccum)
       // premature?
-      if (outAccum === 0) return { fee: fee }
-
+      if (isZero) {
+        return {
+          fee: fee
+        }
+      }
       break
     }
 
-    bytesAccum += outputBytes
-    outAccum += value
+    bytesAccum = ext.add(bytesAccum, outputBytes)
+    outAccum = ext.add(outAccum, value)
     outputs.push(output)
   }
 

index.js

@@ -4,12 +4,12 @@ var utils = require('./utils')
 
 // order by descending value, minus the inputs approximate fee
 function utxoScore (x, feeRate) {
-  return x.value - (feeRate * utils.inputBytes(x))
+  return x.value.sub((feeRate.mul(utils.inputBytes(x))))
 }
 
 module.exports = function coinSelect (utxos, outputs, feeRate) {
   utxos = utxos.concat().sort(function (a, b) {
-    return utxoScore(b, feeRate) - utxoScore(a, feeRate)
+    return utxoScore(b, feeRate).sub(utxoScore(a, feeRate))
   })
 
   // attempt to use the blackjack strategy first (no change output)