From 58ca78f1f180e00c00b495851f14f96d0c9d398e Mon Sep 17 00:00:00 2001
From: julianb0 <spectral@os-k.eu>
Date: Thu, 30 May 2019 19:07:04 +0200
Subject: [PATCH] dos

---
 dos/main.k       |  7 +++----
 dos/str/strrev.k |  7 ++++++-
 pc/mem.c         | 10 ++++++++++
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/dos/main.k b/dos/main.k
index 1a00300..1853574 100644
--- a/dos/main.k
+++ b/dos/main.k
@@ -9,21 +9,20 @@ main:
 
     mov ax0, .msg
     call print
-    break
 
     mov ax0, .buf
     mov ax1, .msg
     call strrev
-    break
 
+    prn 10
     mov ax0, .buf
     call print
 
     leave
     ret
 
-.msg = "Hello World :)\n"
-.buf = "               "
+.msg = "Hello World :)"
+.buf = "!!!!!!!!!!!!!!!!"
 
 ;
 ; Exit function
diff --git a/dos/str/strrev.k b/dos/str/strrev.k
index be2ff88..2f1b2f1 100644
--- a/dos/str/strrev.k
+++ b/dos/str/strrev.k
@@ -10,8 +10,11 @@ strrev:
     jz .4
 
     ; save str's location
-    mov rdx, ax1
+    ; xxx why is dec'ing needed?
+    lea rdx, b[ax1 + -1]
 
+    ; go to str's end, just before
+    ; the null terminator
 .1:
     test b[ax1+1], b[ax1+1]
     jz .2
@@ -19,6 +22,8 @@ strrev:
     inc ax1
     jmp .1
 
+    ; copy, going backward though str
+    ; and forward through buf 
 .2:
     mov b[ax0], b[ax1]
 
diff --git a/pc/mem.c b/pc/mem.c
index d79849a..cf1d95c 100644
--- a/pc/mem.c
+++ b/pc/mem.c
@@ -94,6 +94,15 @@ void writemem8(ctx_t *ctx, ulong val, ulong addr)
 
     ushort v = ctx->mp[real];
 
+    if (!(addr % 2)) {
+        ctx->mp[real] = ((v & 0xFF00) << 8) | (val & 0xFF);
+    }
+
+    else {
+        ctx->mp[real] = (v & 0xFF) | (((val & 0xFF) << 8));
+    }
+
+/*
     if (addr % 2) {
         ctx->mp[real] = (v & 0xFF00) | (val & 0xFF);
     }
@@ -101,6 +110,7 @@ void writemem8(ctx_t *ctx, ulong val, ulong addr)
     else {
         ctx->mp[real] = (v & 0xFF) | (((val & 0xFF) << 8));
     }
+*/
 }
 
 void writemem16(ctx_t *ctx, ulong val, ulong addr)