Skip to content

Ensure loop does not go forever in RNG #461

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
pat-rogers wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Ensure loop does not go forever in RNG #461

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
19 changes: 12 additions & 7 deletions arch/ARM/STM32/drivers/stm32-rng-polling.adb
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
------------------------------------------------------------------------------
-- --
-- Copyright (C) 2015, AdaCore --
-- Copyright (C) 2015-2026, AdaCore --
-- --
-- Redistribution and use in source and binary forms, with or without --
-- modification, are permitted provided that the following conditions are --
Expand Down Expand Up @@ -50,9 +50,7 @@ package body STM32.RNG.Polling is
begin
Enable_RNG_Clock;
Enable_RNG;

-- Discard the first randomly generated number, according to STM32F4
-- docs.
-- Discard the first generated number, according to STM32F4 docs.
Discard := Random;
end Initialize_RNG;

Expand All @@ -61,10 +59,17 @@ package body STM32.RNG.Polling is
------------

function Random return UInt32 is
Max_Attempts : constant := 1000;
-- The above is arbitrary. It needs to be long enough that normal
-- behavior will not be flagged. Longer than that is fine. The point
-- is to not hang forever.
begin
while not RNG_Data_Ready loop
null;
end loop;
Await_Ready : for K in 1 .. Max_Attempts loop
exit when RNG_Data_Ready;
if K = Max_Attempts then
raise Program_Error with "RNG data not ready";
end if;
end loop Await_Ready;
return RNG_Data;
end Random;

Expand Down
Loading