Add base64DecToArr.js.

Author: ekpyron

scripts/ci/base64DecToArr.js

@@ -0,0 +1,47 @@
+/*\
+|*|
+|*|  Base64 / binary data / UTF-8 strings utilities
+|*|
+|*|  https://developer.mozilla.org/en-US/docs/Web/JavaScript/Base64_encoding_and_decoding
+|*|
+\*/
+
+/* Array of bytes to Base64 string decoding */
+
+function b64ToUint6 (nChr) {
+
+  return nChr > 64 && nChr < 91 ?
+      nChr - 65
+    : nChr > 96 && nChr < 123 ?
+      nChr - 71
+    : nChr > 47 && nChr < 58 ?
+      nChr + 4
+    : nChr === 43 ?
+      62
+    : nChr === 47 ?
+      63
+    :
+      0;
+
+}
+
+function base64DecToArr (sBase64, nBlocksSize) {
+
+  var
+    sB64Enc = sBase64.replace(/[^A-Za-z0-9\+\/]/g, ""), nInLen = sB64Enc.length,
+    nOutLen = nBlocksSize ? Math.ceil((nInLen * 3 + 1 >> 2) / nBlocksSize) * nBlocksSize : nInLen * 3 + 1 >> 2, taBytes = new Uint8Array(nOutLen);
+
+  for (var nMod3, nMod4, nUint24 = 0, nOutIdx = 0, nInIdx = 0; nInIdx < nInLen; nInIdx++) {
+    nMod4 = nInIdx & 3;
+    nUint24 |= b64ToUint6(sB64Enc.charCodeAt(nInIdx)) << 6 * (3 - nMod4);
+    if (nMod4 === 3 || nInLen - nInIdx === 1) {
+      for (nMod3 = 0; nMod3 < 3 && nOutIdx < nOutLen; nMod3++, nOutIdx++) {
+        taBytes[nOutIdx] = nUint24 >>> (16 >>> nMod3 & 24) & 255;
+      }
+      nUint24 = 0;
+
+    }
+  }
+
+  return taBytes;
+}