From 345eacf8f1dc29cb4cd836e3d585d30497e7ea72 Mon Sep 17 00:00:00 2001
From: iximeow <me@iximeow.net>
Date: Sun, 2 Aug 2026 19:35:19 +0000
Subject: pkhbt/pkhtb bitmask confusion

---
 CHANGELOG            |  1 +
 src/armv7/thumb.rs   |  2 +-
 tests/armv7/thumb.rs | 12 ++++++++++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG b/CHANGELOG
index 71aa08a..b552484 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -11,6 +11,7 @@
   * the decoder reused the non-thumb encoding table, but thumb opcode/sizes are
     encoded in a different order.
 * thumb2: `ldrexd` was off by one in looking up an opcode
+* thumb2: pkhtb/pkhbt distinction was off by one bit
 * thumb2: `mrs` destinations, which should have been a mask of the current (or
   saved) program status register, was reported as a banked GPR.
 * ARMv8: support thumb2 encoding of `Test Target` instruction, `Opcode::TT`
diff --git a/src/armv7/thumb.rs b/src/armv7/thumb.rs
index 72a2ea6..439c3a6 100644
--- a/src/armv7/thumb.rs
+++ b/src/armv7/thumb.rs
@@ -1013,7 +1013,7 @@ pub fn decode_into<T: Reader<<ARMv7 as Arch>::Address, <ARMv7 as Arch>::Word>>(d
                             // TODO: fix shift
                             // TODO: check opcode
                             inst.s = false;
-                            inst.opcode = if lower & 0b10000 != 0 {
+                            inst.opcode = if lower & 0b100000 != 0 {
                                 Opcode::PKHTB
                             } else {
                                 Opcode::PKHBT
diff --git a/tests/armv7/thumb.rs b/tests/armv7/thumb.rs
index b1b9399..e6e1bfb 100644
--- a/tests/armv7/thumb.rs
+++ b/tests/armv7/thumb.rs
@@ -4573,6 +4573,18 @@ fn msr_mrs() {
 }
 
 #[test]
+fn pkh() {
+    test_display(
+        &[0xc7, 0xea, 0xe8, 0x77],
+        "pkhtb.w r7, r7, r8, asr 31"
+    );
+    test_display(
+        &[0xc7, 0xea, 0xc8, 0x77],
+        "pkhbt.w r7, r7, r8, lsl 31"
+    );
+}
+
+#[test]
 fn test_target() {
     // the v8 manuals list a new Test Target with some variants to it..
     test_nonconforming(
-- 
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