From e3fc396bec308867b5078f6794f8b04e30c571c9 Mon Sep 17 00:00:00 2001
From: Nalin Bhardwaj <nalinbhardwaj@nibnalin.me>
Date: Thu, 13 Jan 2022 16:14:49 -0800
Subject: [PATCH] Drop fnv-plus, handwrite fnv-hash

Closes https://github.com/iden3/circom_runtime/issues/9
---
 build/main.cjs    | 17 +++++++++++------
 js/utils.js       | 14 +++++++++++---
 package-lock.json | 13 +------------
 package.json      |  3 +--
 4 files changed, 24 insertions(+), 23 deletions(-)

diff --git a/build/main.cjs b/build/main.cjs
index d492201..6602499 100644
--- a/build/main.cjs
+++ b/build/main.cjs
@@ -2,13 +2,8 @@
 
 Object.defineProperty(exports, '__esModule', { value: true });
 
-var fnv = require('fnv-plus');
 var ffjavascript = require('ffjavascript');
 
-function _interopDefaultLegacy (e) { return e && typeof e === 'object' && 'default' in e ? e : { 'default': e }; }
-
-var fnv__default = /*#__PURE__*/_interopDefaultLegacy(fnv);
-
 /*
 
 Copyright 2020 0KIMS association.
@@ -44,7 +39,17 @@ function flatArray(a) {
 }
 
 function fnvHash(str) {
-    return fnv__default['default'].hash(str, 64).hex();
+    const uint64_max = BigInt(2) ** BigInt(64);
+    let hash = BigInt("0xCBF29CE484222325");
+    for (var i = 0; i < str.length; i++) {
+    hash ^= BigInt(str[i].charCodeAt());
+    hash *= BigInt(0x100000001B3);
+    hash %= uint64_max;
+    }
+    let shash = hash.toString(16);
+    let n = 16 - shash.length;
+    shash = '0'.repeat(n).concat(shash);
+    return shash;
 }
 
 /* globals WebAssembly */
diff --git a/js/utils.js b/js/utils.js
index 103ac2d..3e69d07 100644
--- a/js/utils.js
+++ b/js/utils.js
@@ -16,8 +16,6 @@ limitations under the License.
 
 */
 
-import fnv from "fnv-plus";
-
 export function flatArray(a) {
     var res = [];
     fillArray(res, a);
@@ -35,5 +33,15 @@ export function flatArray(a) {
 }
 
 export function fnvHash(str) {
-    return fnv.hash(str, 64).hex();
+    const uint64_max = BigInt(2) ** BigInt(64);
+    let hash = BigInt("0xCBF29CE484222325");
+    for (var i = 0; i < str.length; i++) {
+    hash ^= BigInt(str[i].charCodeAt());
+    hash *= BigInt(0x100000001B3);
+    hash %= uint64_max;
+    }
+    let shash = hash.toString(16);
+    let n = 16 - shash.length;
+    shash = '0'.repeat(n).concat(shash);
+    return shash;
 }
diff --git a/package-lock.json b/package-lock.json
index 9922026..9855f50 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,8 +9,7 @@
       "version": "0.1.14",
       "license": "Apache-2.0",
       "dependencies": {
-        "ffjavascript": "0.2.39",
-        "fnv-plus": "^1.3.1"
+        "ffjavascript": "0.2.39"
       },
       "bin": {
         "calcwit": "calcwit.js"
@@ -720,11 +719,6 @@
       "integrity": "sha512-r5wGx7YeOwNWNlCA0wQ86zKyDLMQr+/RB8xy74M4hTphfmjlijTSSXGuH8rnvKZnfT9i+75zmd8jcKdMR4O6jA==",
       "dev": true
     },
-    "node_modules/fnv-plus": {
-      "version": "1.3.1",
-      "resolved": "https://registry.npmjs.org/fnv-plus/-/fnv-plus-1.3.1.tgz",
-      "integrity": "sha512-Gz1EvfOneuFfk4yG458dJ3TLJ7gV19q3OM/vVvvHf7eT02Hm1DleB4edsia6ahbKgAYxO9gvyQ1ioWZR+a00Yw=="
-    },
     "node_modules/fs.realpath": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/fs.realpath/-/fs.realpath-1.0.0.tgz",
@@ -2097,11 +2091,6 @@
       "integrity": "sha512-r5wGx7YeOwNWNlCA0wQ86zKyDLMQr+/RB8xy74M4hTphfmjlijTSSXGuH8rnvKZnfT9i+75zmd8jcKdMR4O6jA==",
       "dev": true
     },
-    "fnv-plus": {
-      "version": "1.3.1",
-      "resolved": "https://registry.npmjs.org/fnv-plus/-/fnv-plus-1.3.1.tgz",
-      "integrity": "sha512-Gz1EvfOneuFfk4yG458dJ3TLJ7gV19q3OM/vVvvHf7eT02Hm1DleB4edsia6ahbKgAYxO9gvyQ1ioWZR+a00Yw=="
-    },
     "fs.realpath": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/fs.realpath/-/fs.realpath-1.0.0.tgz",
diff --git a/package.json b/package.json
index 2b6d4d4..876a62b 100644
--- a/package.json
+++ b/package.json
@@ -34,8 +34,7 @@
   },
   "homepage": "https://github.com/iden3/circom_runtime#readme",
   "dependencies": {
-    "ffjavascript": "0.2.39",
-    "fnv-plus": "^1.3.1"
+    "ffjavascript": "0.2.39"
   },
   "devDependencies": {
     "eslint": "^6.8.0",