From 21c3c594896726d9637caae459faf8999ff7772f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juhani=20Krekel=C3=A4?= <juhani@krekelä.fi>
Date: Fri, 30 Jul 2021 16:18:10 +0300
Subject: [PATCH] More generic macros for specific encodings

---
 edlin.asm | 73 +++++++++++++++++++++++++++++--------------------------
 1 file changed, 38 insertions(+), 35 deletions(-)

diff --git a/edlin.asm b/edlin.asm
index c1a8820..943f9e6 100644
--- a/edlin.asm
+++ b/edlin.asm
@@ -21,36 +21,39 @@ sys_set_dta equ 0x1a
 sys_block_read equ 0x27
 
 ; Special instruction encodings
-%macro add_cx_ax 0
-	db 0x03, 0xC8 ; add cx, ax (direction swapped)
-%endmacro
-%macro add_di_cx 0
-	db 0x03, 0xF9 ; 023E add di, cx (direction swapped)
-%endmacro
+%define r_ax 0
+%define r_cx 1
+%define r_dx 2
+%define r_bx 3
+%define r_sp 4
+%define r_bp 5
+%define r_si 6
+%define r_di 7
 
-%macro sub_cx_di 0
-	db 0x2b, 0xcf ; sub cx, di (direction swapped)
-%endmacro
+%define r_al 0
+%define r_cl 1
+%define r_dl 2
+%define r_bl 3
+%define r_ah 4
+%define r_ch 5
+%define r_dh 6
+%define r_bh 7
 
-%macro or_al_al 0
-	db 0x0a, 0xc0 ; or al, al (direction swapped)
+; Direction swapped reg, reg
+%macro addw 2
+	db 0x03, 0xc0 + 8 * %1 + %2
 %endmacro
-
-%macro xor_ax_ax 0
-	db 0x33, 0xc0 ; xor ax, ax (direction swapped)
+%macro orb 2
+	db 0x0a, 0xc0 + 8 * %1 + %2
 %endmacro
-
-%macro mov_ax_cx 0
-	db 0x8b, 0xc1 ; mov ax, cx (direction swapped)
+%macro subw 2
+	db 0x2b, 0xc0 + 8 * %1 + %2
 %endmacro
-%macro mov_dx_cx 0
-	db 0x8b, 0xD1 ; mov dx, cx (direction swapped)
+%macro xorw 2
+	db 0x33, 0xc0 + 8 * %1 + %2
 %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)
+%macro movw 2
+	db 0x8b, 0xc0 + 8 * %1 + %2
 %endmacro
 
 %macro cmp_byteaddr_bytext 2
@@ -84,7 +87,7 @@ ensure_file_argument:
 	je print_filename_missing_error
 
 	; AL at program start a flag of whether drive specifier in first parameter valid
-	or_al_al
+	orb r_al, r_al
 	mov dx, invalid_name_error
 	jnz _trampoline_error_1
 
@@ -100,7 +103,7 @@ open_file:
 	int 0x21
 
 	mov [new_file_flag], al
-	or_al_al
+	orb r_al, r_al
 	jz delete_old_bak
 
 	mov dx, new_file_str
@@ -130,7 +133,7 @@ delete_old_bak: ; 01b9
 
 	mov ah, sys_create_file
 	int 0x21
-	or_al_al
+	orb r_al, r_al
 	jz setup_file_parameters
 
 	mov dx, directory_full_error
@@ -141,7 +144,7 @@ print_bak_error: ; 01e6
 	jmp error
 
 setup_file_parameters: ; 01ec
-	xor_ax_ax
+	xorw r_ax, r_ax
 	mov [psp_fcb_1 + fcb_record_low], ax
 	mov [psp_fcb_1 + fcb_record_high], ax
 	mov [__0a58_fcb + fcb_record_low], ax
@@ -152,7 +155,7 @@ setup_file_parameters: ; 01ec
 	mov [__0a58_fcb + fcb_record_size], ax
 
 	mov dx, disk_transfer_area
-	mov_di_dx
+	movw r_di, r_dx
 	mov ah, sys_set_dta
 	int 0x21
 
@@ -168,13 +171,13 @@ setup_file_parameters: ; 01ec
 
 	; __0a94 = ¼ available memory
 	shr cx, 1
-	mov_ax_cx
+	movw r_ax, r_cx
 	shr cx, 1
 	mov [__0a94], cx
 	; cx = ¾ available memory
-	add_cx_ax
+	addw r_cx, r_ax
 
-	mov_dx_cx
+	movw r_dx, r_cx
 	add dx, disk_transfer_area
 	mov [__0a96], dx
 
@@ -183,7 +186,7 @@ read_file:
 	mov ah, sys_block_read
 	int 0x21
 	call find_file_end_char
-	add_di_cx
+	addw r_di, r_cx
 
 __0240:
 db 0xFC ; 0240 cld
@@ -313,11 +316,11 @@ find_file_end_char: ; 035e
 
 	mov al, 0x1a ; ^Z
 	repne scasb
-	mov_di_cx
+	movw r_di, r_cx
 
 	pop cx
 	lahf
-	sub_cx_di
+	subw r_cx, r_di
 	sahf
 
 	pop di