Simplify bit shifts calc

Remove the two reverse() calls

Author: dingosky

src/lib/bits.spec.ts

@@ -11,6 +11,13 @@ test('Chars.Safe32', (t) => t.deepEqual(bitShifts(Chars.Safe32), [[32, 5]]))
 
 test('Chars.AlphaNum', (t) => t.deepEqual(bitShifts(Chars.AlphaNum), [[62, 6]]))
 
+test('Chars.Alpha', (t) =>
+  t.deepEqual(bitShifts(Chars.Alpha), [
+    [ 52, 6 ],
+    [ 55, 5 ],
+    [ 63, 3 ]
+   ]))
+
 test('Chars.AlphaLower', (t) =>
   t.deepEqual(bitShifts(Chars.AlphaLower), [
     [26, 5],
@@ -31,5 +38,3 @@ test('Chars.SafeAscii', (t) =>
     [95, 5],
     [127, 2]
   ]))
-
-// test('Chars.AlphaNumLower', (t) => t.deepEqual(bitShifts(Chars.AlphaNumLower), [[62, 6]]))

src/lib/bits.ts

@@ -42,23 +42,20 @@ const bitShifts = (chars: string): BitShifts => {
 
   if (isPow2(chars.length)) return [baseBitShift]
 
-  const zeroBitShifts = new Array(nBitsPerChar)
-    .fill(null)
-    .reduce((acc, _n, ndx) => {
-      acc.push(ndx)
-      return acc
-    }, [])
-    .slice(2)
-    .reverse()
-    .reduce((shifts: BitShifts, bit: number) => {
-      if (isBitZero(chars.length, bit)) {
-        const shift: BitShift = [chars.length | (pow2(bit) - 1), nBitsPerChar - bit + 1]
-        return shifts.concat([shift])
-      }
-      return shifts
-    }, [])
-  zeroBitShifts.push(baseBitShift)
-  return zeroBitShifts.reverse()
+  return new Array(nBitsPerChar)
+  .fill(null)
+  .reduce((acc, _n, ndx) => {
+    acc.push(ndx)
+    return acc
+  }, [])
+  .slice(2)
+  .reduce((shifts: BitShifts, bit: number) => {
+    if (isBitZero(chars.length, bit)) {
+      const shift: BitShift = [chars.length | pow2(bit) - 1, nBitsPerChar - bit + 1]
+      return shifts.concat([shift])
+    }
+    return shifts
+  }, [baseBitShift])
 }
 
 const valueAt = (lOffset: number, nBits: number, puidBytes: PuidBytes): number => {