Int decoder

aeternity · Mar 13, 2020 · 2be1005 · 2be1005
1 parent 8a4ffd8
commit 2be1005
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Showing 7 changed files with 93 additions and 6 deletions.
diff --git a/src/Serializers/IntSerializer.js b/src/Serializers/IntSerializer.js
@@ -1,9 +1,13 @@
+const RLP = require('rlp')
 const FateTag = require('../FateTag.js')
 const RLPInt = require('../utils/RLPInt.js')
 const FateInt = require('../types/FateInt.js')
+const {ByteArray2Int} = require('../utils/Int2ByteArray.js')
 
 const abs = (val) => val > 0 ? val : val * -1n
 
+const SMALL_INT_MASK = 0b00000001
+
 IntSerializer = function () {}
 
 IntSerializer.prototype = {
@@ -35,6 +39,32 @@ IntSerializer.prototype = {
             FateTag.POS_BIG_INT,
             ...RLPInt(absVal - 64n)
         ]
+    },
+    deserialize: function (data) {
+        data = new Uint8Array(data)
+        const prefix = data[0]
+
+        //small int
+        if ((prefix & SMALL_INT_MASK) === 0) {
+            // positive
+            if ((prefix & 0b10000000) === 0) {
+                return new FateInt(prefix >> 1)
+            }
+
+            // negative
+            const i = (prefix & 0b01111110) >> 1
+            return new FateInt(-i)
+        }
+
+        if (prefix === FateTag.POS_BIG_INT || prefix === FateTag.NEG_BIG_INT) {
+            const sign = prefix === FateTag.POS_BIG_INT ? 1n : -1n
+            const i = ByteArray2Int(RLP.decode(data.slice(1)))
+
+            return new FateInt((i + 64n) * sign)
+
+        }
+
+        throw new Error('Unsupported byte sequence for ' + prefix.toString(2))
     }
 }
 

diff --git a/src/types/FateBytes.js b/src/types/FateBytes.js
@@ -1,5 +1,5 @@
 const FateData = require('./FateData.js')
-const Int2ByteArray = require('../utils/Int2ByteArray.js')
+const {Int2ByteArray} = require('../utils/Int2ByteArray.js')
 const HexStringToByteArray = require('../utils/HexStringToByteArray.js')
 
 const toByteArray = (value) => {

diff --git a/src/utils/Int2ByteArray.js b/src/utils/Int2ByteArray.js
@@ -1,4 +1,4 @@
-const Int2ByteArray = function (value) {
+const Int2ByteArray =  (value) => {
     if (value < 256) {
         return new Uint8Array([Number(value)])
     }
@@ -16,4 +16,23 @@ const Int2ByteArray = function (value) {
     ])
 }
 
-module.exports = Int2ByteArray
+const ByteArray2Int = (data) => {
+    var hex = [];
+
+    data.forEach(i => {
+        var h = i.toString(16)
+
+        if (h.length % 2) {
+            h = '0' + h;
+        }
+
+        hex.push(h)
+    })
+
+    return BigInt('0x' + hex.join(''))
+}
+
+module.exports = {
+    Int2ByteArray,
+    ByteArray2Int
+}
diff --git a/src/utils/RLPInt.js b/src/utils/RLPInt.js
@@ -1,5 +1,5 @@
 const RLP = require('rlp')
-const Int2ByteArray = require('./Int2ByteArray.js')
+const {Int2ByteArray} = require('./Int2ByteArray.js')
 
 module.exports = function RLPInt(value) {
     return new Uint8Array(RLP.encode(Int2ByteArray(value)))

diff --git a/tests/Decoder.js b/tests/Decoder.js
@@ -11,9 +11,17 @@ test.before(async t => {
     t.context.encoder = encoder
 });
 
-test('Encode boolean return', t => {
+test('Decode boolean return', t => {
     t.is(
         t.context.encoder.decode(CONTRACT, 'test_bool', 'cb_/8CwV/U='),
         true
     )
 });
+
+test('Decode int return', t => {
+    t.is(
+        t.context.encoder.decode(CONTRACT, 'test_single_int', 'cb_b4MC7W/bKkpn'),
+        191919n,
+        'test_single_int(191919)'
+    )
+});
diff --git a/tests/Serializers/IntSerializer.js b/tests/Serializers/IntSerializer.js
@@ -20,3 +20,17 @@ test('Serialize', t => {
         [111,136,254,220,186,152,118,84,49,208]
     )
 });
+
+test('Deserialize', t => {
+    t.deepEqual(s.deserialize([0]), new FateInt(0))
+    t.deepEqual(s.deserialize([126]), new FateInt(63))
+    t.deepEqual(s.deserialize([254]), new FateInt(-63))
+    t.deepEqual(s.deserialize([111, 0]), new FateInt(64))
+    t.deepEqual(s.deserialize([239, 0]), new FateInt(-64))
+    t.deepEqual(s.deserialize([111, 131, 1, 134, 96]), new FateInt(100000))
+    t.deepEqual(s.deserialize([239, 131, 1, 134, 96]), new FateInt(-100000))
+    t.deepEqual(
+        s.deserialize([111,136,254,220,186,152,118,84,49,208]),
+        new FateInt("0xfedcba9876543210")
+    )
+});
diff --git a/tests/utils/Int2ByteArray.js b/tests/utils/Int2ByteArray.js
@@ -1,5 +1,5 @@
 const test = require('ava')
-const Int2ByteArray = require('../../src/utils/Int2ByteArray.js')
+const {Int2ByteArray, ByteArray2Int} = require('../../src/utils/Int2ByteArray.js')
 
 const b = (value) => new Uint8Array(value)
 
@@ -18,3 +18,19 @@ test('Int2ByteArray', t => {
         b([2,30,25,224,201,186,178,216,150,127])
     )
 });
+
+test('ByteArray2Int', t => {
+    t.deepEqual(ByteArray2Int([0]), 0n)
+    t.deepEqual(ByteArray2Int([1]), 1n)
+    t.deepEqual(ByteArray2Int([255]), 255n)
+    t.deepEqual(ByteArray2Int([1, 0]), 256n)
+    t.deepEqual(ByteArray2Int([1, 44]), 300n)
+    t.deepEqual(ByteArray2Int([1, 255]), 511n)
+    t.deepEqual(ByteArray2Int([2, 0]), 512n)
+    t.deepEqual(ByteArray2Int([2, 40]), 552n)
+    t.deepEqual(ByteArray2Int([1, 134, 160]), 100000n)
+    t.deepEqual(
+        ByteArray2Int([2,30,25,224,201,186,178,216,150,127]),
+        10000000000000009999999n
+    )
+});