scriptnum: improve encoding.

lib/script/scriptnum.js

@@ -43,14 +43,14 @@ Object.setPrototypeOf(ScriptNum.prototype, I64.prototype);
  * @returns {Number}
  */
 
-ScriptNum.prototype.toInt = function toInt() {
-  if (this.lt(I64.UINT32_MIN))
+ScriptNum.prototype.getInt = function getInt() {
+  if (this.lt(I64.INT32_MIN))
     return I64.LONG_MIN;
 
-  if (this.gt(I64.UINT32_MAX))
+  if (this.gt(I64.INT32_MAX))
     return I64.LONG_MAX;
 
-  return this.lo;
+  return this.toInt();
 };
 
 /**
@@ -128,6 +128,7 @@ ScriptNum.prototype.toRaw = function toRaw() {
 
 ScriptNum.prototype.fromRaw = function fromRaw(data) {
   assert(Buffer.isBuffer(data));
+  assert(data.length <= 9);
 
   // Empty arrays are always zero.
   if (data.length === 0)
@@ -240,6 +241,30 @@ ScriptNum.isMinimal = function isMinimal(data) {
   return true;
 };
 
+/**
+ * Encode a script number.
+ * @param {Number|ScriptNum|BN} num
+ * @returns {Buffer}
+ */
+
+ScriptNum.encode = function encode(num) {
+  assert(num != null);
+
+  if (ScriptNum.isScriptNum(num))
+    return num.encode();
+
+  if (typeof num === 'number')
+    num = ScriptNum.fromNumber(num);
+  else if (I64.isN64(num))
+    num = ScriptNum.fromObject(num);
+  else if (Array.isArray(num.words))
+    num = ScriptNum.fromBN(num);
+  else
+    throw new Error('Object must be encodable.');
+
+  return num.encode();
+};
+
 /**
  * Decode and verify script number.
  * @param {Buffer} data
@@ -252,6 +277,31 @@ ScriptNum.decode = function decode(data, minimal, limit) {
   return new ScriptNum().decode(data, minimal, limit);
 };
 
+/**
+ * Test whether object is encodable.
+ * @param {Object} obj
+ * @returns {Boolean}
+ */
+
+ScriptNum.isEncodable = function isEncodable(obj) {
+  if (obj == null)
+    return false;
+
+  if (ScriptNum.isScriptNum(obj))
+    return true;
+
+  if (typeof obj === 'number')
+    return true;
+
+  if (I64.isN64(obj))
+    return true;
+
+  if (Array.isArray(obj.words))
+    return true;
+
+  return false;
+};
+
 /**
  * Test whether object is a script number.
  * @param {Object} obj