Library improvements:

– random module
– ensure_mixedcase() function

docs/stdlib/other.md

@@ -14,6 +14,10 @@ Prints a string of length `len` located at address `str`.
 Prints a null-terminated string located at address `str`.  
 If the string is longer than 255 bytes, then the behaviour is undefined (might even crash).
 
+#### `void ensure_mixedcase()`
+
+On targets that have separate all-caps and mixed-case modes (like most Commodore machines), switches to the mixed-case mode.
+
 
 ## err
 
@@ -24,3 +28,29 @@ Standard error codes. All codes other than `err_ok` suggest that the last operat
 #### `error_number errno`
 
 The result of the last operation.
+
+
+## random
+
+A simple and reasonably fast random number generator. Not suitable for cryptographic or simulation uses.
+
+#### `word rand_seed`
+
+Random number generator state.
+
+#### `byte rand()`
+
+Get a random byte (0–255) and update the state of the generator.
+
+#### `void init_rand_seed()`
+
+Initializes the random number generator state.
+This may take a long time, even several frames, depending on the target.
+
+Current implementation:  
+
+* On C64, spends two frames reading noise data from the SID chip.
+
+* On Z80, reads the refresh register.
+
+* On all other targets, sets the seed to 1.