random lib and homescreen improvements

bootstrap.py

@@ -0,0 +1,8 @@
+# minimal one-file ota-bootstrap
+
+import usocket, ujson, os, time, gc, wifi
+
+# todo
+
+if __name__ == '__main__':
+    bootstrap()

lib/homescreen.py

@@ -36,6 +36,8 @@ def init(enable_menu_button = True):
         buttons.enable_interrupt("BTN_MENU", lambda t: set_state("menu"), on_release = True)
 
 def set_state(key, value = True):
+    # we can't allocate memory in interrupts, so make sure all keys are set beforehand and
+    # you're only using numbers and booleans
     global _state
     _state[key] = value
 
@@ -57,8 +59,8 @@ def name(default = None):
     return database.get("homescreen.name", default)
 
 def wifi_strength():
-    return random.rand() / 256
+    return random.random()
 
 def battery():
-    return random.rand() / 256
+    return random.random()
 

lib/random.py

@@ -1,9 +1,40 @@
-"""Library to generate random numbers"""
+"""Library to generate random numbers
+
+Warning! Don't use this for anything important, it's probably biased
+"""
 
 ___license___ = "MIT"
 
 import os
 
-# todo: write an actual useful function
-def rand():
-    return int(os.urandom(1)[0])
+_bigrand_bytes = 10
+_bigrand_max = pow(256, _bigrand_bytes)
+
+def _bigrand():
+    """generates a random number between 0 (incl) and _bigrand_max (excl)"""
+    base = 0
+    for b in os.urandom(_bigrand_bytes):
+        base = (base << 8) + b
+    return base
+
+def random():
+    """Return the next random floating point number in the range [0.0, 1.0)."""
+    return _bigrand() / _bigrand_max
+
+def randrange(start, stop=None):
+    """Return a randomly selected element from range(start, stop)"""
+    if stop is None:
+        stop = start
+        start = 0
+    return start + (_bigrand() * (stop - start) // _bigrand_max)
+
+def randint(start, stop):
+    """Return a random integer N such that a <= N <= b."""
+    return randrange(start, stop + 1)
+
+def shuffle(seq):
+    """Shuffle the sequence x in place."""
+    l = len(seq)
+    for i in range(l):
+        j = randrange(l)
+        seq[i], seq[j] = seq[j], seq[i]

lib/test_random.py

@@ -8,12 +8,31 @@ from random import *
 
 class TestRandom(unittest.TestCase):
 
-    def test_rand(self):
+    def test_random(self):
         for i in range(1, 100):
-            r = rand()
-            self.assertTrue(r>0)
-            self.assertTrue(r<256)
+            r = random()
+            self.assertTrue(r>=0)
+            self.assertTrue(r<=1)
 
+    def test_randint(self):
+        for i in range(1, 100):
+            r = randint(500, 1000)
+            self.assertTrue(r>=500)
+            self.assertTrue(r<=1000)
+
+    def test_randrange(self):
+        for i in range(1, 100):
+            r = randrange(10)
+            self.assertTrue(r>=0)
+            self.assertTrue(r<10)
+
+    def test_shuffle(self):
+        for i in range(1, 100):
+            r = list(range(1, 10))
+            shuffle(r)
+            self.assertEqual(sum(r), 45)
+            self.assertEqual(set(r), set(range(1, 10)))
+            self.assertNotEqual(r, list(range(1, 10)))
 
 
 if __name__ == '__main__':