From 67d1405c157236aafab5f6f15a9be6481f4868c9 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Tue, 29 Dec 2015 13:13:51 -0800
Subject: [PATCH] handle compact mantissa numbers.

---
 lib/bcoin/output.js |   2 +-
 lib/bcoin/script.js |   2 +-
 lib/bcoin/utils.js  | 111 ++++++++++++++++++++++++--------------------
 3 files changed, 62 insertions(+), 53 deletions(-)

diff --git a/lib/bcoin/output.js b/lib/bcoin/output.js
index ad2ee879..5c415a81 100644
--- a/lib/bcoin/output.js
+++ b/lib/bcoin/output.js
@@ -200,7 +200,7 @@ Output.getData = function getData(output) {
   }
 
   if (bcoin.script.isScripthash(s)) {
-    hash = utils.toHex(sub[1]);
+    hash = sub[1];
     addr = bcoin.wallet.hash2addr(hash, 'scripthash');
     return utils.merge(def, {
       type: 'scripthash',
diff --git a/lib/bcoin/script.js b/lib/bcoin/script.js
index 181561f7..ffb0ddc0 100644
--- a/lib/bcoin/script.js
+++ b/lib/bcoin/script.js
@@ -1187,7 +1187,7 @@ script.coinbaseBits = function coinbaseBits(s, block) {
   if (s[0].length > 6)
     return { type: 'value', value: s[0] };
 
-  value = new bn(s[0].reverse()).toNumber();
+  value = new bn(s[0].slice().reverse()).toNumber();
 
   // Test for bits and ts
   if (block) {
diff --git a/lib/bcoin/utils.js b/lib/bcoin/utils.js
index d94010a0..ed40319d 100644
--- a/lib/bcoin/utils.js
+++ b/lib/bcoin/utils.js
@@ -420,57 +420,6 @@ function binaryInsert(list, item, compare, search) {
 
 utils.binaryInsert = binaryInsert;
 
-function bitsToTarget(bits) {
-  var len = (bits >>> 24) & 0xff;
-  var hi = (bits >>> 16) & 0xff;
-  var mid = (bits >>> 8) & 0xff;
-  var lo = bits & 0xff;
-  var res = new Array(len);
-  var i = 0;
-
-  for (; i < len - 3; i++)
-    res[i] = 0;
-
-  res[i++] = lo;
-  res[i++] = mid;
-  res[i++] = hi;
-
-  if (hi === 0)
-    res.pop();
-
-  if (hi === 0 && mid === 0)
-    res.pop();
-
-  return res;
-}
-
-utils.bitsToTarget = bitsToTarget;
-
-function testTarget(target, hash) {
-  var i;
-
-  if (typeof target === 'number')
-    target = bitsToTarget(target);
-
-  hash = utils.toArray(hash, 'hex');
-
-  for (i = hash.length - 1; i >= target.length; i--)
-    if (hash[i] !== 0)
-      return false;
-
-  for (; i >= 0; i--) {
-    if (hash[i] === target[i])
-      continue;
-    if (hash[i] > target[i])
-      return false;
-    break;
-  }
-
-  return true;
-}
-
-utils.testTarget = testTarget;
-
 utils.isEqual = function isEqual(a, b) {
   var i = 0;
 
@@ -811,3 +760,63 @@ utils.uniq = function(obj) {
 
   return out;
 };
+
+utils.fromCompact = function fromCompact(compact) {
+  var exponent = compact >> 24;
+  var negative = (compact >> 23) & 0x01;
+  var mantissa = compact & 0x007fffff;
+  var num;
+
+  if (compact === 0)
+    return new bn(0);
+
+  if (exponent <= 3) {
+    mantissa >>= 8 * (3 - exponent);
+    num = new bn(mantissa);
+  } else {
+    num = new bn(mantissa);
+    num.iushln(8 * (exponent - 3));
+  }
+
+  if (negative)
+    num.ineg();
+
+  return num;
+};
+
+utils.toCompact = function toCompact(num) {
+  var mantissa, exponent, compact;
+
+  if (num.cmpn(0) === 0)
+    return 0;
+
+  exponent = num.byteLength();
+  if (exponent <= 3) {
+    mantissa = num.toNumber();
+    mantissa <<= 8 * (3 - exponent);
+  } else {
+    mantissa = num.ushrn(8 * (exponent - 3)).toNumber();
+  }
+
+  if (mantissa & 0x00800000) {
+    mantissa >>= 8;
+    exponent++;
+  }
+
+  compact = (exponent << 24) | mantissa;
+
+  if (num.isNeg())
+    compact |= 0x00800000;
+
+  return compact;
+};
+
+utils.testTarget = function testTarget(target, hash) {
+  if (typeof target === 'number')
+    target = utils.fromCompact(target);
+
+  if (typeof hash === 'string')
+    hash = utils.toArray(hash, 'hex');
+
+  return new bn(hash.slice().reverse()).cmp(target) < 0;
+};