From 059f48b0c426f9a0c901bc0b9c1fef09b29c2632 Mon Sep 17 00:00:00 2001
From: Daniel Cousens <github@dcousens.com>
Date: Tue, 5 Jan 2016 01:59:14 +1100
Subject: [PATCH] script_number: add impl/tests
---
src/script_number.js | 78 +++++++++++
test/fixtures/script_number.json | 225 +++++++++++++++++++++++++++++++
test/script_number.js | 27 ++++
3 files changed, 330 insertions(+)
create mode 100644 src/script_number.js
create mode 100644 test/fixtures/script_number.json
create mode 100644 test/script_number.js
diff --git a/src/script_number.js b/src/script_number.js
new file mode 100644
index 0000000..857e44b
--- /dev/null
+++ b/src/script_number.js
@@ -0,0 +1,78 @@
+function decode (buffer, maxLength, minimal) {
+ maxLength = maxLength || 4
+ minimal = minimal === undefined ? true : minimal
+
+ var length = buffer.length
+ if (length === 0) return 0
+ if (length > maxLength) throw new TypeError('Script number overflow')
+ if (minimal) {
+ if ((buffer[length - 1] & 0x7f) === 0) {
+ if (length <= 1 || (buffer[length - 2] & 0x80) === 0) throw new Error('Non-minimally encoded script number')
+ }
+ }
+
+ // 32-bit?
+ if (length < 5) {
+ var result = 0
+
+ for (var i = 0; i < length; ++i) {
+ result += buffer[i] << (8 * i)
+ }
+
+ if (buffer[length - 1] & 0x80) return -(result & ~(0x80 << (8 * (length - 1))))
+ return result
+ }
+
+ // 40-bit
+ var a = buffer.readUInt32LE(0)
+ var b = buffer.readUInt8(4)
+
+ // TODO: refactor
+ var neg = false
+ if (b & 0x80) {
+ b &= ~0x80
+ neg = true
+ }
+
+ var r = b * 0x100000000 + a
+
+ if (neg) {
+ r = -r
+ }
+
+ return r
+}
+
+function scriptNumSize (i) {
+ return i > 0x7fffffff ? 5
+ : i > 0x7fffff ? 4
+ : i > 0x7fff ? 3
+ : i > 0x7f ? 2
+ : i > 0x00 ? 1
+ : 0
+}
+
+function encode (number) {
+ var value = Math.abs(number)
+ var size = scriptNumSize(value)
+ var buffer = new Buffer(size)
+ var negative = number < 0
+
+ for (var i = 0; i < size; ++i) {
+ buffer.writeUInt8(value & 0xff, i)
+ value >>= 8
+ }
+
+ if (buffer[size - 1] & 0x80) {
+ buffer.writeUInt8(negative ? 0x80 : 0x00, size - 1)
+ } else if (negative) {
+ buffer[size - 1] |= 0x80
+ }
+
+ return buffer
+}
+
+module.exports = {
+ decode: decode,
+ encode: encode
+}
diff --git a/test/fixtures/script_number.json b/test/fixtures/script_number.json
new file mode 100644
index 0000000..f934740
--- /dev/null
+++ b/test/fixtures/script_number.json
@@ -0,0 +1,225 @@
+[
+ {
+ "hex": "",
+ "number": 0
+ },
+ {
+ "hex": "01",
+ "number": 1
+ },
+ {
+ "hex": "02",
+ "number": 2
+ },
+ {
+ "hex": "03",
+ "number": 3
+ },
+ {
+ "hex": "7e",
+ "number": 126
+ },
+ {
+ "hex": "7f",
+ "number": 127
+ },
+ {
+ "hex": "8000",
+ "number": 128
+ },
+ {
+ "hex": "8100",
+ "number": 129
+ },
+ {
+ "hex": "8200",
+ "number": 130
+ },
+ {
+ "hex": "ff00",
+ "number": 255
+ },
+ {
+ "hex": "fe7f",
+ "number": 32766
+ },
+ {
+ "hex": "ff7f",
+ "number": 32767
+ },
+ {
+ "hex": "008000",
+ "number": 32768
+ },
+ {
+ "hex": "ffff00",
+ "number": 65535
+ },
+ {
+ "hex": "018000",
+ "number": 32769
+ },
+ {
+ "hex": "028000",
+ "number": 32770
+ },
+ {
+ "hex": "ffffff00",
+ "number": 16777215
+ },
+ {
+ "hex": "feff7f",
+ "number": 8388606
+ },
+ {
+ "hex": "ffff7f",
+ "number": 8388607
+ },
+ {
+ "hex": "00008000",
+ "number": 8388608
+ },
+ {
+ "hex": "01008000",
+ "number": 8388609
+ },
+ {
+ "hex": "02008000",
+ "number": 8388610
+ },
+ {
+ "hex": "feffff7f",
+ "number": 2147483646
+ },
+ {
+ "hex": "ffffff7f",
+ "number": 2147483647
+ },
+ {
+ "bytes": 5,
+ "hex": "0000008000",
+ "number": 2147483648
+ },
+ {
+ "bytes": 5,
+ "hex": "0100008000",
+ "number": 2147483649
+ },
+ {
+ "bytes": 5,
+ "hex": "0200008000",
+ "number": 2147483650
+ },
+ {
+ "bytes": 5,
+ "hex": "ffffffff00",
+ "number": 4294967295
+ },
+ {
+ "bytes": 5,
+ "hex": "0200008080",
+ "number": -2147483650
+ },
+ {
+ "bytes": 5,
+ "hex": "0100008080",
+ "number": -2147483649
+ },
+ {
+ "bytes": 5,
+ "hex": "0000008080",
+ "number": -2147483648
+ },
+ {
+ "hex": "ffffffff",
+ "number": -2147483647
+ },
+ {
+ "hex": "feffffff",
+ "number": -2147483646
+ },
+ {
+ "hex": "fdffffff",
+ "number": -2147483645
+ },
+ {
+ "hex": "ffffff80",
+ "number": -16777215
+ },
+ {
+ "hex": "01008080",
+ "number": -8388609
+ },
+ {
+ "hex": "00008080",
+ "number": -8388608
+ },
+ {
+ "hex": "ffffff",
+ "number": -8388607
+ },
+ {
+ "hex": "feffff",
+ "number": -8388606
+ },
+ {
+ "hex": "fdffff",
+ "number": -8388605
+ },
+ {
+ "hex": "ffff80",
+ "number": -65535
+ },
+ {
+ "hex": "018080",
+ "number": -32769
+ },
+ {
+ "hex": "008080",
+ "number": -32768
+ },
+ {
+ "hex": "ffff",
+ "number": -32767
+ },
+ {
+ "hex": "feff",
+ "number": -32766
+ },
+ {
+ "hex": "fdff",
+ "number": -32765
+ },
+ {
+ "hex": "ff80",
+ "number": -255
+ },
+ {
+ "hex": "8180",
+ "number": -129
+ },
+ {
+ "hex": "8080",
+ "number": -128
+ },
+ {
+ "hex": "ff",
+ "number": -127
+ },
+ {
+ "hex": "fe",
+ "number": -126
+ },
+ {
+ "hex": "fd",
+ "number": -125
+ },
+ {
+ "hex": "82",
+ "number": -2
+ },
+ {
+ "hex": "81",
+ "number": -1
+ }
+]
diff --git a/test/script_number.js b/test/script_number.js
new file mode 100644
index 0000000..8200df3
--- /dev/null
+++ b/test/script_number.js
@@ -0,0 +1,27 @@
+/* global describe, it */
+
+var assert = require('assert')
+var scriptNumber = require('../src/script_number')
+var fixtures = require('./fixtures/script_number.json')
+
+describe('script', function () {
+ describe('decode', function () {
+ fixtures.forEach(function (f) {
+ it(f.hex + ' returns ' + f.number, function () {
+ var actual = scriptNumber.decode(new Buffer(f.hex, 'hex'), f.bytes)
+
+ assert.strictEqual(actual, f.number)
+ })
+ })
+ })
+
+ describe('encode', function () {
+ fixtures.forEach(function (f) {
+ it(f.number + ' returns ' + f.hex, function () {
+ var actual = scriptNumber.encode(f.number)
+
+ assert.strictEqual(actual.toString('hex'), f.hex)
+ })
+ })
+ })
+})