diff --git a/asd.js b/asd.js
index 585b837..cde1bac 100644
--- a/asd.js
+++ b/asd.js
@@ -1,4 +1,5 @@
 import { replaceFunctions, Commands, CommandsByValue, u16_swap } from "./func_replacements.js";
+import { placeholderTypes, sprintf } from "./utils.js";
 
 const hook_fn = (name_in_elf, enter, leave) => {
   var symbol_addr = DebugSymbol.fromName(name_in_elf).address;
@@ -47,8 +48,8 @@ const hook___android_log_print = () => {
       // let _prio = args[0].toInt32();
       let _tag = args[1].readCString();
       let fmt = args[2].readCString();
-      // console.log(fmt); // debug if crashes due to missing placeholder
       const types = placeholderTypes(fmt); // ['s', 'd', ..]`
+      // console.log(fmt, types); // debug if crashes due to missing placeholder
 
       let o = {
         s: (x) => x.readCString(),
@@ -98,6 +99,7 @@ const hook_udpsend = () => {
       }
     },
   );
+
   let s = {};
   hook_fn(
     "PktSeq_seqGet",
@@ -110,6 +112,42 @@ const hook_udpsend = () => {
       console.log(data);
     },
   );
+
+  let e = {};
+  hook_fn(
+    "XqBytesEnc",
+    (args) => {
+      s.buf_ptr = args[0];
+      s.m_buflen = args[1].toInt32();
+      s.param3 = args[2].toInt32();
+      s.buf_in = s.buf_ptr.readByteArray(s.m_buflen);
+    },
+    (retval) => {
+      const bufout = s.buf_ptr.readByteArray(s.m_buflen);
+      console.log(`XqBytesEnc buflen: ${s.m_buflen}, param3: ${s.param3}, buf_in:`);
+      console.log(s.buf_in);
+      console.log(`bufout`);
+      console.log(bufout);
+    },
+  );
+
+  let d = {};
+  hook_fn(
+    "XqBytesDec",
+    (args) => {
+      s.buf_ptr = args[0];
+      s.m_buflen = args[1].toInt32();
+      s.param3 = args[2].toInt32();
+      s.buf_in = s.buf_ptr.readByteArray(s.m_buflen);
+    },
+    (retval) => {
+      const bufout = s.buf_ptr.readByteArray(s.m_buflen);
+      console.log(`XqBytesDec buflen: ${s.m_buflen}, param3: ${s.param3}, buf_in:`);
+      console.log(s.buf_in);
+      console.log(`bufout`);
+      console.log(bufout);
+    },
+  );
 };
 
 const hook_in_out_buf = (sym, insize, outsize) => {
@@ -190,22 +228,4 @@ function doHooks() {
     console.log("NO WORKING");
   }
 }
-
-const matchy = /%[0-9.-]*([a-z])/g;
-const replacy = /(.*?)%[0-9.-]*([a-z])/g;
-
-const placeholderTypes = (str) => {
-  // '%-16s, line %4d, %-16s:ret=%d,broadcast lan_seach to %s:%.3f!!!!'
-  // =>
-  // [ 's', 'd', 's', 'd', 's', 'f' ]
-  return [...str.matchAll(matchy)].map((m) => m[1]);
-};
-const sprintf = (str, values) => {
-  // '%-16s, line %4d, %-16s:ret=%d,broadcast lan_seach to %s:%.3f!!!!' +
-  // ["asd", 20, ...]
-  // =>
-  // asd, line 20, ...
-  const matches = str.matchAll(replacy);
-  return [...matches].map((m, idx) => m[1] + values[idx].toString()).join("");
-};
 setImmediate(doHooks);
diff --git a/func_replacements.js b/func_replacements.js
index a796be0..fb0dc0c 100644
--- a/func_replacements.js
+++ b/func_replacements.js
@@ -1,8 +1,45 @@
 export const u16_swap = (x) => ((x & 0xff00) >> 8) | ((x & 0x00ff) << 8);
 
+export const XqBytesDec = (inoutbuf, buflen, rotate) => {
+  let new_buf = new Uint8Array(buflen);
+  new_buf.fill(0x1);
+  for (let i = 0; i < buflen; i++) {
+    let b = inoutbuf.add(i).readU8();
+    if ((b & 1) != 0) {
+      new_buf[i] = b - 1;
+    } else {
+      new_buf[i] = b + 1;
+    }
+  }
+  for (let i = rotate; i < buflen; i++) {
+    inoutbuf.add(i).writeU8(new_buf[i - rotate]);
+  }
+  for (let i = 0; i < rotate; i++) {
+    inoutbuf.add(i).writeU8(new_buf[buflen - rotate + i]);
+  }
+};
+export const XqBytesEnc = (inoutbuf, buflen, rotate) => {
+  let new_buf = new Uint8Array(buflen);
+  new_buf.fill(0x1);
+  for (let i = 0; i < buflen; i++) {
+    let b = inoutbuf.add(i).readU8();
+    if ((b & 1) != 0) {
+      new_buf[i] = b - 1;
+    } else {
+      new_buf[i] = b + 1;
+    }
+  }
+  for (let i = 0; i < buflen - rotate; i++) {
+    inoutbuf.add(i).writeU8(new_buf[i + rotate]);
+  }
+  for (let i = 0; i < rotate; i++) {
+    inoutbuf.add(buflen - rotate + i).writeU8(new_buf[i]);
+  }
+};
+
 const swap_endianness_u16 = (ptr) => {
   const bytes = ptr.readU16();
-  const swapped = [ (bytes & 0xff00) >> 8, bytes & 0x00ff ];
+  const swapped = [(bytes & 0xff00) >> 8, bytes & 0x00ff];
   return swapped;
 };
 const swap_endianness_u32 = (ptr) => {
@@ -43,28 +80,28 @@ const compare_buf = (a, b, len) => {
 };
 
 export const Commands = {
-  Close : 0xf1f0,
-  LanSearchExt : 0xf132,
-  LanSearch : 0xf130,
-  P2PAlive : 0xf1e0,
-  P2PAliveAck : 0xf1e1,
-  Hello : 0xf100,
-  P2pRdy : 0xf142,
-  P2pReq : 0xf120,
-  LstReq : 0xf167,
-  DrwAck : 0xf1d1,
-  Drw : 0xf1d0,
+  Close: 0xf1f0,
+  LanSearchExt: 0xf132,
+  LanSearch: 0xf130,
+  P2PAlive: 0xf1e0,
+  P2PAliveAck: 0xf1e1,
+  Hello: 0xf100,
+  P2pRdy: 0xf142,
+  P2pReq: 0xf120,
+  LstReq: 0xf167,
+  DrwAck: 0xf1d1,
+  Drw: 0xf1d0,
 
   // From CSession_CtrlPkt_Proc, incomplete
-  PunchTo : 0xf140,
-  PunchPkt : 0xf141,
-  HelloAck : 0xf101,
-  RlyTo : 0xf102,
-  DevLgnAck : 0xf111,
-  P2PReqAck : 0xf121,
-  ListenReqAck : 0xf169,
-  RlyHelloAck : 0xf170,  // always
-  RlyHelloAck2 : 0xf171, // if len >1??
+  PunchTo: 0xf140,
+  PunchPkt: 0xf141,
+  HelloAck: 0xf101,
+  RlyTo: 0xf102,
+  DevLgnAck: 0xf111,
+  P2PReqAck: 0xf121,
+  ListenReqAck: 0xf169,
+  RlyHelloAck: 0xf170, // always
+  RlyHelloAck2: 0xf171, // if len >1??
 };
 
 export const CommandsByValue = Object.keys(Commands).reduce((acc, cur) => {
@@ -72,7 +109,7 @@ export const CommandsByValue = Object.keys(Commands).reduce((acc, cur) => {
   return acc;
 }, {});
 
-export const reply_Drw = (inbuf, outbuf) => {
+const reply_Drw = (inbuf, outbuf) => {
   /*
   -> cmd = inbuf+10
   -> chan = inbuf+9
@@ -87,11 +124,11 @@ export const reply_Drw = (inbuf, outbuf) => {
   const chan = inbuf.add(9).readU16();
   const cmd = inbuf.add(10).readU16();
   const param2 = 0xd2; // ?
-  const half_len = 1;  // FIXME
-  const bare_ack = Memory.alloc(half_len * 2 + 8);
+  const half_len = 1; // FIXME u16_swap(inbuf.add(0xc).readU16());
+  const bare_ack = Memory.alloc(half_len * 2 + 8 + 4); // fixme +4
   create_DrwAck(bare_ack, param2, chan, half_len, inbuf);
   const hdr_len = pack_P2pHdr(bare_ack, outbuf);
-  pack_DrwAck(bare_ack + 4, half_len * 2 + 4, outbuf.add(hdr_len));
+  pack_DrwAck(bare_ack.add(4), half_len * 2 + 4, outbuf.add(hdr_len));
 };
 const pack_P2pHdr = (inbuf, out_buf) => {
   // shitty memcpy
@@ -100,10 +137,10 @@ const pack_P2pHdr = (inbuf, out_buf) => {
 };
 
 const writeCommand2 = (command, buf) => {
-  buf.writeByteArray([ (command & 0xff00) >> 8, command & 0xff ]);
+  buf.writeByteArray([(command & 0xff00) >> 8, command & 0xff]);
 };
 const writeCommand4 = (command, buf) => {
-  buf.writeByteArray([ (command & 0xff00) >> 8, command & 0xff, 0x00, 0x00 ]);
+  buf.writeByteArray([(command & 0xff00) >> 8, command & 0xff, 0x00, 0x00]);
 };
 const create_Close = (buf) => {
   writeCommand4(Commands.Close, buf);
@@ -147,8 +184,6 @@ const create_P2pRdy = (outbuf, inbuf) => {
   return P2PRDY_SIZE + 4;
 };
 
-create_P2pRdy(new ArrayBuffer(16), ...);
-
 const create_P2pReq = (outbuf, inbuf, m_s_addr, addr_fam) => {
   const P2PREQ_SIZE = 0x24;
   writeCommand2(Commands.P2pReq, outbuf);
@@ -161,8 +196,7 @@ const create_P2pReq = (outbuf, inbuf, m_s_addr, addr_fam) => {
   outbuf.add(2 * 0xf).writeByteArray(swap_endianness_u16(m_s_addr.add(2)));
 
   outbuf.add(2 * 0x12).writeU64(0);
-  outbuf.add(2 * 0x10).writeByteArray(
-      swap_endianness_u32(m_s_addr.add(4))); // ip address
+  outbuf.add(2 * 0x10).writeByteArray(swap_endianness_u32(m_s_addr.add(4))); // ip address
 
   return P2PREQ_SIZE + 4;
 };
@@ -192,8 +226,7 @@ const create_LstReq = (outbuf, inbuf) => {
   // 0xc * sizeof(short)
   outbuf.add(2 * 0xc).writeU32(inbuf.add(0x10).readU32());
 
-  return LISTREQ_SIZE +
-         4; // this is actually wrong (and unused) in the code -- it is 0x1c
+  return LISTREQ_SIZE + 4; // this is actually wrong (and unused) in the code -- it is 0x1c
 };
 
 const create_DrwAck = (outbuf, idk_param2, channel, half_len, inbuf) => {
@@ -210,15 +243,14 @@ const create_DrwAck = (outbuf, idk_param2, channel, half_len, inbuf) => {
 };
 
 const dbg_create_Drw = (og_func) => {
-  const create_Drw =
-      (outbuf, idk_param2, idk_param3, idk_param4, copy_len, inbuf) => {
-        /// idk_param4 goes up by 0x100 per call
+  const create_Drw = (outbuf, idk_param2, idk_param3, idk_param4, copy_len, inbuf) => {
+    /// idk_param4 goes up by 0x100 per call
 
-        // console.log(
-        //   `2: ${idk_param2.toString(16)} 3: ${idk_param3.toString(16)} 4:
-        //   ${idk_param4.toString(16)} copylen: ${copy_len}`,
-        //);
-        /*
+    // console.log(
+    //   `2: ${idk_param2.toString(16)} 3: ${idk_param3.toString(16)} 4:
+    //   ${idk_param4.toString(16)} copylen: ${copy_len}`,
+    //);
+    /*
          * 2: ffffffd1 3: 0 4: 3100 copylen: 44
             In buffer
                                0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F
@@ -237,22 +269,21 @@ const dbg_create_Drw = (og_func) => {
          ................ 00000030  01 01 01 01
             */
 
-        const copy_len_swapped = u16_swap(copy_len + 4);
-        writeCommand2(Commands.Drw, outbuf);
-        outbuf.add(2).writeU16(copy_len_swapped);
-        outbuf.add(8).writeU8(0xd1);
-        outbuf.add(10).writeU16(idk_param4);
-        outbuf.add(12).writeByteArray(inbuf.readByteArray(copy_len));
+    const copy_len_swapped = u16_swap(copy_len + 4);
+    writeCommand2(Commands.Drw, outbuf);
+    outbuf.add(2).writeU16(copy_len_swapped);
+    outbuf.add(8).writeU8(0xd1);
+    outbuf.add(10).writeU16(idk_param4);
+    outbuf.add(12).writeByteArray(inbuf.readByteArray(copy_len));
 
-        return copy_len + 8;
-      };
+    return copy_len + 8;
+  };
   return create_Drw;
 };
 const dbg_pack_ClntPkt = (og_func) => {
   const pack_ClntPkt = (addr_fam, inbuf, outbuf) => {
     const cmd = u16_swap(inbuf.readU16());
-    console.log(`pack_ClntPkt: cmd 0x${cmd.toString(16)} = ${
-        CommandsByValue[cmd]}; fam ${addr_fam}; inbuf =>`);
+    console.log(`pack_ClntPkt: cmd 0x${cmd.toString(16)} = ${CommandsByValue[cmd]}; fam ${addr_fam}; inbuf =>`);
     // console.log(inbuf.readByteArray(16));
 
     // const ret = og_func(addr_fam, inbuf, outbuf);
@@ -260,19 +291,17 @@ const dbg_pack_ClntPkt = (og_func) => {
     // const new_outbuf = Memory.alloc(ret);
     const hdrLen = pack_P2pHdr(inbuf, outbuf);
     const packFn = {
-      [Commands.LanSearch] : () => hdrLen,
-      [Commands.LanSearchExt] : () => hdrLen,
-      [Commands.Close] : () => hdrLen,
-      [Commands.Hello] : () => hdrLen,
-      [Commands.P2pReq] : () =>
-          hdrLen + pack_P2pReq4(inbuf.add(8), outbuf.add(hdrLen)),
-      [Commands.LstReq] : () =>
-          hdrLen + pack_P2pId(inbuf.add(8), outbuf.add(hdrLen)),
-      [Commands.DrwAck] : () => {
+      [Commands.LanSearch]: () => hdrLen,
+      [Commands.LanSearchExt]: () => hdrLen,
+      [Commands.Close]: () => hdrLen,
+      [Commands.Hello]: () => hdrLen,
+      [Commands.P2pReq]: () => hdrLen + pack_P2pReq4(inbuf.add(8), outbuf.add(hdrLen)),
+      [Commands.LstReq]: () => hdrLen + pack_P2pId(inbuf.add(8), outbuf.add(hdrLen)),
+      [Commands.DrwAck]: () => {
         const pkt_size = u16_swap(inbuf.add(2).readU16());
         return hdrLen + pack_DrwAck(inbuf.add(8), pkt_size, outbuf.add(hdrLen));
       },
-      [Commands.Drw] : () => {
+      [Commands.Drw]: () => {
         const pkt_size = u16_swap(inbuf.add(2).readU16());
         return hdrLen + pack_Drw(inbuf.add(8), pkt_size, outbuf.add(hdrLen));
       },
@@ -306,8 +335,7 @@ const pack_Drw = (inbuf, m_pkt_size, outbuf) => {
   outbuf.writeU8(inbuf.readU8());
   outbuf.add(1).writeU8(inbuf.add(1).readU8());
   outbuf.add(2).writeU16(inbuf.add(2).readU16());
-  outbuf.add(4).writeByteArray(
-      inbuf.add(4).readByteArray(m_pkt_size - DRW_HDR_SIZE));
+  outbuf.add(4).writeByteArray(inbuf.add(4).readByteArray(m_pkt_size - DRW_HDR_SIZE));
 
   return m_pkt_size;
 };
@@ -319,8 +347,7 @@ const pack_DrwAck = (inbuf, m_pkt_size, outbuf) => {
   outbuf.writeU8(inbuf.readU8());
   outbuf.add(1).writeU8(inbuf.add(1).readU8());
   outbuf.add(2).writeU16(inbuf.add(2).readU16());
-  outbuf.add(4).writeByteArray(
-      inbuf.add(4).readByteArray(m_pkt_size - DRW_ACK_HDR_SIZE));
+  outbuf.add(4).writeByteArray(inbuf.add(4).readByteArray(m_pkt_size - DRW_ACK_HDR_SIZE));
 
   return m_pkt_size;
 };
@@ -339,7 +366,7 @@ const pack_P2pReq4 = (inbuf, outbuf) => {
   return 0x24;
 };
 
-export const replace_func = (stub, ret, args) => {
+const replace_func = (stub, ret, args) => {
   const name_in_elf = stub.name.replace("dbg_", ""); // UGH  FIXME
   const symbol_addr = DebugSymbol.fromName(name_in_elf).address;
   if (symbol_addr == 0) {
@@ -356,11 +383,9 @@ export const replace_func = (stub, ret, args) => {
     replacement_func = stub;
   }
 
-  console.log(
-      `Replacing ${name_in_elf}, signature "${ret} ${name_in_elf}(${args})"`);
+  console.log(`Replacing ${name_in_elf}, signature "${ret} ${name_in_elf}(${args})"`);
 
-  Interceptor.replace(symbol_addr,
-                      new NativeCallback(replacement_func, ret, args));
+  Interceptor.replace(symbol_addr, new NativeCallback(replacement_func, ret, args));
 };
 
 /* Send_Pkt_LanSearch =
@@ -378,31 +403,40 @@ export const replace_func = (stub, ret, args) => {
 // CSession_CtrlPkt_Proc(struct, *cmd) == control?
 export const replaceFunctions = () => {
   const replacements = [
-    [ create_P2pAlive, "uint8", [ "pointer" ] ],
-    [ create_P2pAliveAck, "uint8", [ "pointer" ] ],
-    [ create_LanSearch, "uint8", [ "pointer" ] ],
-    [ create_LanSearchExt, "uint8", [ "pointer" ] ],
-    [ create_Hello, "uint8", [ "pointer" ] ],
-    [ create_Close, "uint8", [ "pointer" ] ],
-    [
-      dbg_create_Drw, "uint",
-      [ "pointer", "uint64", "uint8", "uint16", "uint32", "pointer" ]
-    ],
-    [
-      create_DrwAck, "uint",
-      [ "pointer", "uint8", "uint8", "uint16", "pointer" ]
-    ],
-    [ create_P2pReq, "uint8", [ "pointer", "pointer", "pointer", "uint" ] ],
-    [ create_LstReq, "uint8", [ "pointer", "pointer" ] ],
-    [ create_P2pRdy, "uint8", [ "pointer", "pointer" ] ],
-    [ pack_P2pHdr, "uint8", [ "pointer", "pointer" ] ],
-    [ pack_Drw, "uint8", [ "pointer", "uint16", "pointer" ] ],
-    [ pack_DrwAck, "uint8", [ "pointer", "uint16", "pointer" ] ],
-    [ pack_P2pId, "uint32", [ "pointer", "pointer" ] ],
-    [ pack_P2pReq4, "uint64", [ "pointer", "pointer" ] ],
-    [ dbg_pack_ClntPkt, "uint32", [ "uint32", "pointer", "pointer" ] ],
+    [create_P2pAlive, "uint8", ["pointer"]],
+    [create_P2pAliveAck, "uint8", ["pointer"]],
+    [create_LanSearch, "uint8", ["pointer"]],
+    [create_LanSearchExt, "uint8", ["pointer"]],
+    [create_Hello, "uint8", ["pointer"]],
+    [create_Close, "uint8", ["pointer"]],
+    [dbg_create_Drw, "uint", ["pointer", "uint64", "uint8", "uint16", "uint32", "pointer"]],
+    [create_DrwAck, "uint", ["pointer", "uint8", "uint8", "uint16", "pointer"]],
+    [create_P2pReq, "uint8", ["pointer", "pointer", "pointer", "uint"]],
+    [create_LstReq, "uint8", ["pointer", "pointer"]],
+    [create_P2pRdy, "uint8", ["pointer", "pointer"]],
+    [pack_P2pHdr, "uint8", ["pointer", "pointer"]],
+    [pack_Drw, "uint8", ["pointer", "uint16", "pointer"]],
+    [pack_DrwAck, "uint8", ["pointer", "uint16", "pointer"]],
+    [pack_P2pId, "uint32", ["pointer", "pointer"]],
+    [pack_P2pReq4, "uint64", ["pointer", "pointer"]],
+    [dbg_pack_ClntPkt, "uint32", ["uint32", "pointer", "pointer"]],
   ];
 
   replacements.forEach((x) => replace_func(...x));
   return replacements.map((x) => x[0].name.replace("dbg_", ""));
 };
+
+const setMemory = (m) => {
+  global.Memory = m;
+};
+/*
+module.exports = {
+  replaceFunctions,
+  u16_swap,
+  Commands,
+  CommandsByValue,
+  reply_Drw,
+  replace_func,
+  setMemory,
+};
+*/
diff --git a/shim.js b/shim.js
index c04ac52..6a3feda 100644
--- a/shim.js
+++ b/shim.js
@@ -37,3 +37,12 @@ DataView.prototype.readByteArray = function (len) {
   }
   return ret;
 };
+
+const Memory = {
+  alloc: (len) => new DataView(new ArrayBuffer(len + 1)),
+  copy: (outbuf, inbuf, len) => outbuf.writeByteArray(inbuf.readByteArray(len)),
+};
+
+//module.exports = {
+//  Memory,
+//};
diff --git a/tests/fn.test.js b/tests/fn.test.js
new file mode 100644
index 0000000..51ff1df
--- /dev/null
+++ b/tests/fn.test.js
@@ -0,0 +1,91 @@
+import "../shim.js";
+
+import assert from "assert";
+
+import { placeholderTypes, sprintf } from "../utils.js";
+import { XqBytesDec, XqBytesEnc } from "../func_replacements.js";
+
+describe("debug_tools", () => {
+  it("parses printed data", () => {
+    const fmt = "string: %s, int: %d, float: %f, hexint: %02x, newline: \n\n last int: %d";
+    const expected_placeholders = ["s", "d", "f", "x", "d"];
+    const actual_placeholders = placeholderTypes(fmt);
+    assert.deepEqual(actual_placeholders, expected_placeholders);
+  });
+  it("prints data back", () => {
+    const fmt = "string: %s, int: %d, float: %f, hexint: %02x, newline: \n\n last int: %d";
+    const in_values = ["potato", 5, 3.5, 0x20, 999];
+    const expected_string = "string: potato, int: 5, float: 3.5, hexint: 0x20, newline: \n\n last int: 999";
+    assert.deepEqual(sprintf(fmt, in_values), expected_string);
+  });
+});
+
+describe("module", () => {
+  const simple_enc_bytes = new Uint8Array([
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00,
+  ]);
+  const simple_dec_bytes = new Uint8Array([
+    0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  ]);
+  const long_enc_bytes = new Uint8Array([
+    0x01, 0x01, 0x01, 0x01, 0x03, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x43, 0x40, 0x55, 0x42, 0x37, 0x31, 0x38, 0x34, 0x32, 0x30, 0x44, 0x59, 0x4d, 0x57, 0x52, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x30, 0x33, 0x32, 0x35, 0x34,
+    0x37, 0x36, 0x39, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x31, 0x2f, 0x33, 0x34, 0x34, 0x2f, 0x33, 0x34, 0x34, 0x2f,
+    0x33, 0x34, 0x34, 0x01, 0x01, 0x01, 0x31, 0x2f, 0x31, 0x2f, 0x31, 0x2f, 0x31, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x31, 0x2f, 0x31, 0x2f, 0x31, 0x2f, 0x31, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x31, 0x2f, 0x31, 0x2f, 0x31, 0x2f, 0x31, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x31, 0x2f, 0x31,
+    0x2f, 0x31, 0x2f, 0x31, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+  ]);
+  const long_dec_bytes = new Uint8Array([
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x42, 0x41, 0x54, 0x43, 0x36, 0x30, 0x39, 0x35, 0x33, 0x31, 0x45, 0x58, 0x4c, 0x56,
+    0x53, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x31,
+    0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 0x2e, 0x32, 0x35, 0x35, 0x2e,
+    0x32, 0x35, 0x35, 0x2e, 0x32, 0x35, 0x35, 0x00, 0x00, 0x00, 0x30, 0x2e, 0x30, 0x2e, 0x30, 0x2e, 0x30, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 0x2e, 0x30, 0x2e, 0x30, 0x2e, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x30, 0x2e, 0x30, 0x2e, 0x30, 0x2e, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x30, 0x2e, 0x30, 0x2e, 0x30, 0x2e, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  ]);
+  it("decrypts simple input", () => {
+    const in_buf = new DataView(simple_enc_bytes.buffer.slice(0));
+    XqBytesDec(in_buf, simple_enc_bytes.byteLength, 4); // this mutates in_buf
+    assert.deepEqual(new Uint8Array(in_buf.buffer), simple_dec_bytes);
+  });
+  it("decrypts more complex input", () => {
+    const in_buf = new DataView(long_enc_bytes.buffer.slice(0));
+    XqBytesDec(in_buf, long_enc_bytes.byteLength, 4); // this mutates in_buf
+    assert.deepEqual(new Uint8Array(in_buf.buffer), long_dec_bytes);
+  });
+  it("encrypts simple input", () => {
+    const in_buf = new DataView(simple_dec_bytes.buffer.slice(0));
+    XqBytesEnc(in_buf, simple_dec_bytes.byteLength, 4); // this mutates in_buf
+    assert.deepEqual(new Uint8Array(in_buf.buffer), simple_enc_bytes);
+  });
+  it("encrypts more complex input", () => {
+    const in_buf = new DataView(long_dec_bytes.buffer.slice(0));
+    XqBytesEnc(in_buf, long_dec_bytes.byteLength, 4); // this mutates in_buf
+    assert.deepEqual(new Uint8Array(in_buf.buffer), long_enc_bytes);
+  });
+  it("reverts Enc with Dec", () => {
+    const in_buf = new DataView(long_dec_bytes.buffer.slice(0));
+    XqBytesEnc(in_buf, long_dec_bytes.byteLength, 4); // this mutates in_buf
+    assert.deepEqual(new Uint8Array(in_buf.buffer), long_enc_bytes); // ENC
+    XqBytesDec(in_buf, long_dec_bytes.byteLength, 4); // this mutates in_buf
+    assert.deepEqual(new Uint8Array(in_buf.buffer), long_dec_bytes); //DEC
+  });
+});
diff --git a/utils.js b/utils.js
new file mode 100644
index 0000000..4653c46
--- /dev/null
+++ b/utils.js
@@ -0,0 +1,23 @@
+const matchy = /%[0-9.-]*([a-z])/g;
+const replacy = /(?<pre>.*?)%(?<num>[0-9.-]+)*(?<formatter>[a-z])/gs;
+
+export const placeholderTypes = (str) => {
+  // '%-16s, line %4d, %-16s:ret=%d,broadcast lan_seach to %s:%.3f!!!!'
+  // =>
+  // [ 's', 'd', 's', 'd', 's', 'f' ]
+  return [...str.matchAll(matchy)].map((m) => m[1]);
+};
+export const sprintf = (str, values) => {
+  // '%-16s, line %4d, %-16s:ret=%d,broadcast lan_seach to %s:%.3f!!!!' +
+  // ["asd", 20, ...]
+  // =>
+  // asd, line 20, ...
+  const matches = str.matchAll(replacy);
+  return [...matches]
+    .map((m, idx) => {
+      const cur = values[idx];
+      const val = m.groups.formatter == "x" ? `0x${cur.toString(16)}` : cur.toString();
+      return m.groups.pre + val;
+    })
+    .join("");
+};