From: notaz <notasas@gmail.com>
Date: Tue, 13 Oct 2020 20:19:47 +0000 (+0300)
Subject: add a hack for Decap Attack
X-Git-Tag: v2.00~668^2
X-Git-Url: https://notaz.gp2x.de/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1d366b1ad9362fd463c42979c8a687dfc7f46c46;p=picodrive.git

add a hack for Decap Attack

Should delay the pull-up affect instead, but probably nothing needs
this whole thing anyway.
---

diff --git a/pico/memory.c b/pico/memory.c
index a31a08e9..a46760da 100644
--- a/pico/memory.c
+++ b/pico/memory.c
@@ -270,7 +270,12 @@ static NOINLINE u32 port_read(int i)
   u32 in, out;
 
   out = data_reg & ctrl_reg;
-  out |= 0x7f & ~ctrl_reg; // pull-ups
+
+  // pull-ups: should be 0x7f, but Decap Attack has a bug where it temp.
+  // disables output before doing TH-low read, so don't emulate it for TH.
+  // Decap Attack reportedly doesn't work on Nomad but works on must
+  // other MD revisions (different pull-up strength?).
+  out |= 0x3f & ~ctrl_reg;
 
   in = port_readers[i](i, out);