From d47321c53b63c307950e7b6831c36a88d26fb730 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juhani=20Krekel=C3=A4?= <juhani@krekelä.fi>
Date: Fri, 30 Jul 2021 16:06:56 +0300
Subject: [PATCH] Scan for ^Z

---
 edlin.asm | 39 +++++++++++++++++++++++++--------------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/edlin.asm b/edlin.asm
index 3a63945..c1a8820 100644
--- a/edlin.asm
+++ b/edlin.asm
@@ -28,6 +28,10 @@ sys_block_read equ 0x27
 	db 0x03, 0xF9 ; 023E add di, cx (direction swapped)
 %endmacro
 
+%macro sub_cx_di 0
+	db 0x2b, 0xcf ; sub cx, di (direction swapped)
+%endmacro
+
 %macro or_al_al 0
 	db 0x0a, 0xc0 ; or al, al (direction swapped)
 %endmacro
@@ -42,8 +46,11 @@ sys_block_read equ 0x27
 %macro mov_dx_cx 0
 	db 0x8b, 0xD1 ; mov dx, cx (direction swapped)
 %endmacro
+%macro mov_di_cx 0
+	db 0x8b, 0xf9 ; mov di, cx (direction swapped)
+%endmacro
 %macro mov_di_dx 0
-	db 0x8B, 0xfa ; mov di, dx (direction swapped)
+	db 0x8b, 0xfa ; mov di, dx (direction swapped)
 %endmacro
 
 %macro cmp_byteaddr_bytext 2
@@ -175,7 +182,7 @@ read_file:
 	mov dx, psp_fcb_1
 	mov ah, sys_block_read
 	int 0x21
-	call __035e
+	call find_file_end_char
 	add_di_cx
 
 __0240:
@@ -300,18 +307,22 @@ db 0x17 ; 035A pop ss
 db 0x04, 0xA6 ; 035B add al,0xa6
 db 0x08 ; 035D db 0x08
 
-__035e:
-db 0x57 ; 035E push di
-db 0x51 ; 035F push cx
-db 0xB0, 0x1A ; 0360 mov al,0x1a
-db 0xF2, 0xAE ; 0362 repne scasb
-db 0x8B, 0xF9 ; 0364 mov di,cx
-db 0x59 ; 0366 pop cx
-db 0x9F ; 0367 lahf
-db 0x2B, 0xCF ; 0368 sub cx,di
-db 0x9E ; 036A sahf
-db 0x5F ; 036B pop di
-db 0xC3 ; 036C ret
+find_file_end_char: ; 035e
+	push di
+	push cx
+
+	mov al, 0x1a ; ^Z
+	repne scasb
+	mov_di_cx
+
+	pop cx
+	lahf
+	sub_cx_di
+	sahf
+
+	pop di
+	ret
+
 db 0xE9, 0x8E, 0x00 ; 036D jmp 0x3fe
 db 0xF6, 0x06, 0x7E, 0x0A, 0xFF ; 0370 test byte [0xa7e],0xff
 db 0x75, 0xF6 ; 0375 jnz 0x36d