From bb7730d3ce66eaf7d29caf8f8dcc3452e6fa8eb7 Mon Sep 17 00:00:00 2001
From: julianb0 <spectral@os-k.eu>
Date: Thu, 16 May 2019 20:11:17 +0200
Subject: [PATCH] jcxz ftw

---
 as/Makefile | 2 +-
 pc/INSTRS   | 3 +--
 pc/jumps.c  | 7 +++++++
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/as/Makefile b/as/Makefile
index c72179f..29e151a 100644
--- a/as/Makefile
+++ b/as/Makefile
@@ -1,4 +1,4 @@
 # The OS/K Team licenses this file to you under the MIT license.
 # See the LICENSE file in the project root for more information.
 
-all: k-as.py
+k-as: k-as.py
diff --git a/pc/INSTRS b/pc/INSTRS
index e9b308a..258fc6a 100644
--- a/pc/INSTRS
+++ b/pc/INSTRS
@@ -133,8 +133,7 @@ jb i
 jbe r
 jbe i
 
-# Jump if RCX is 0
-#jcxz
+jcxz
 
 #
 # Movement instructions
diff --git a/pc/jumps.c b/pc/jumps.c
index 5123fe7..607aa4f 100644
--- a/pc/jumps.c
+++ b/pc/jumps.c
@@ -65,3 +65,10 @@ IMPL_START_1(jbe)
         ctx->r[RIP].val = v1;
 }
 IMPL_END;
+
+IMPL_START_1(jcxz)
+{
+    if (!ctx->r[RCX].val)
+        ctx->r[RIP].val = v1;
+}
+IMPL_END;