From 9ca2b9bfe9eae3b939889382222aec9bb9e9cbfc Mon Sep 17 00:00:00 2001
From: Ketmar Dark <ketmar@ketmar.no-ip.org>
Date: Sat, 15 Aug 2020 12:43:30 +0300
Subject: [PATCH] 4x8 driver with "<MORE>" prompt

---
 output_driver_4x8.zas | 64 ++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 61 insertions(+), 3 deletions(-)

diff --git a/output_driver_4x8.zas b/output_driver_4x8.zas
index aa2141c..f2243df 100644
--- a/output_driver_4x8.zas
+++ b/output_driver_4x8.zas
@@ -1,4 +1,5 @@
 emitXY defw 0
+emitBeforeScroll defb 1
 
 emitInit:
   ld    hl,#4000
@@ -8,6 +9,10 @@ emitInit:
   ldir
   ld    a,64
   ld    (WIDTH),a
+  ld    hl,0
+  ld    (emitXY),hl
+  ld    a,1
+  ld    (emitBeforeScroll),a
   ret
 
 
@@ -42,8 +47,7 @@ OSWRCH:
   ; need to scroll
   ld    d,23
   push  de
-  ld    b,24
-  call  #0E00
+  call  .doscroll
   pop   de
 .noscroll:
   ld    a,e
@@ -97,6 +101,8 @@ OSWRCH:
 .scrmask equ $-1
   ld    c,a
   ld    a,(hl)
+  nop
+.inverse_cmd equ $-1
   and   #00     ; patched above
 .fontmask equ $-1
   or    c
@@ -130,9 +136,61 @@ OSWRCH:
   ld    h,23
   ld    (emitXY),hl
   ; scroll screen
+  call  .doscroll
+  jr    .exit
+
+.doscroll:
+  ld    a,(emitBeforeScroll)
+  dec   a
+  jr    nz,.noprompt
+  ; show scroll prompt, wait a key
+  ld    a,(.charcode)
+  push  af
+  ld    a,#2F   ; CPL
+  ld    (.inverse_cmd),a
+  ld    hl,(emitXY)
+  push  hl
+  ld    hl,#173A
+  push  hl
+  ld    (emitXY),hl
+  ld    hl,.scrollmsg
+.msgloop:
+  ld    a,(hl)
+  and   #7f
+  call  OSWRCH
+  bit   7,(hl)
+  inc   hl
+  jr    z,.msgloop
+.waitrelease:
+  call  #028E
+  inc   e
+  jr    nz,.waitrelease
+.waitpress:
+  call  #028E
+  inc   e
+  jr    z,.waitpress
+  ; clear message area
+  pop   hl
+  ld    (emitXY),hl
+  xor   a
+  ld    (.inverse_cmd),a
+  ld    b,6
+.clrmsg:
+  ld    a,' '
+  call  OSWRCH
+  djnz  .clrmsg
+  pop   hl
+  ld    (emitXY),hl
+  pop   af
+  ld    (.charcode),a
+  ld    a,23
+.noprompt:
+  ld    (emitBeforeScroll),a
   ld    b,24
   call  #0E00
-  jr    .exit
+  ret
+
+.scrollmsg: defx "<MORE>"
 
 font4x8:
   ; space
-- 
2.11.4.GIT