optimised and corrected primes func drastically

src/kindlekey.py

@@ -126,23 +126,26 @@ def SHA256(message):
 # For K4M/PC 1.6.X and later
 # generate table of prime number less than or equal to int n
 def primes(n):
-    if n==2: return [2]
+    """
-    elif n<2: return []
+    Return a list of prime integers smaller than or equal to n
-    s=range(3,n+1,2)
+    :param n: int
-    mroot = n ** 0.5
+    :return: list->int
-    half=(n+1)/2-1
+    """
-    i=0
+    if n == 2:
-    m=3
+        return [2]
-    while m <= mroot:
+    elif n < 2:
-        if s[i]:
+        return []
-            j=(m*m-3)/2
+    primeList = [2]
-            s[j]=0
+
-            while j<half:
+    for potentialPrime in range(3, n + 1, 2):
-                s[j]=0
+        isItPrime = True
-                j+=m
+        for prime in primeList:
-        i=i+1
+            if potentialPrime % prime == 0:
-        m=2*i+3
+                isItPrime = False
-    return [2]+[x for x in s if x]
+        if isItPrime is True:
+            primeList.append(potentialPrime)
+
+    return primeList
 
 # Encode the bytes in data with the characters in map
 def encode(data, map):