From c1f02faf5cbb522f092b6e9f3c564f5327baa8d1 Mon Sep 17 00:00:00 2001
From: Ketmar Dark <ketmar@ketmar.no-ip.org>
Date: Sat, 15 Aug 2020 13:43:19 +0300
Subject: [PATCH] added Einar Saukas' optimisation to disasm, cut 2 bytes

---
 disz80.zas | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/disz80.zas b/disz80.zas
index e6a5ad9..9ded2a7 100644
--- a/disz80.zas
+++ b/disz80.zas
@@ -16,6 +16,8 @@ CHROP_RET:
   ret
 
 DISASM_USE_HEX_PREFIX equ 1
+; Einar Saukas' optimisation, cut 2 bytes
+DISASM_EINAR_OPTIMISATION equ 1
 
 ; ====================
 ; DIS-Z80 was published in the SUBSET column of Personal Computer World 1987.
@@ -34,6 +36,7 @@ DISASM_USE_HEX_PREFIX equ 1
 ;
 ; k8: sadly, i had to add some mode code, so it is 1101 bytes now
 ; (including `EMIT_CB` variable)
+; or 1099 bytes with Einar's optimisation ;-)
 ;
 ; IN:
 ;   DE: address to disasm from
@@ -722,17 +725,28 @@ $ENDIF
 
 ;****************
 
+$IF DISASM_EINAR_OPTIMISATION
+SKIP:
+  bit   7,(hl)
+  inc   hl
+  jr    z,SKIP
+  dec   a
 XTRACT:
   or    a
-  jr    z,COPY
+  jr    nz,SKIP
 
+$ELSE
+
+XTRACT:
+  or    a
+  jr    z,COPY
 SKIP:
   bit   7,(hl)
   inc   hl
   jr    z,SKIP
-
   dec   a
   jr    nz,SKIP
+$ENDIF
 
 COPY:
   ld    a,(hl)
-- 
2.11.4.GIT