From 56d22db6e030c986fed785c5c9e9c20e4c5876ee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juhani=20Krekel=C3=A4?= <juhani@krekelä.fi>
Date: Thu, 16 Mar 2023 19:22:59 +0200
Subject: [PATCH] Bump cpu level to 286 and use pusha/popa where possible

---
 ponydos.asm | 58 +++++++++++++++--------------------------------------
 1 file changed, 16 insertions(+), 42 deletions(-)

diff --git a/ponydos.asm b/ponydos.asm
index a5a71e3..30bab61 100644
--- a/ponydos.asm
+++ b/ponydos.asm
@@ -1,4 +1,4 @@
-cpu 8086
+cpu 286
 bits 16
 
 org 0x7c00
@@ -106,9 +106,7 @@ mainloop:
 ; ------------------------------------------------------------------
 
 draw_wallpaper:
-	push ax
-	push bx
-	push cx
+	pusha
 	push es
 
 	mov bx, 0xb800
@@ -120,15 +118,11 @@ draw_wallpaper:
 	rep movsw
 
 	pop es
-	pop cx
-	pop bx
-	pop ax
+	popa
 	ret
 
 flip_mouse_cursor:
-	push ax
-	push bx
-	push cx
+	pusha
 	push es
 
 	mov bx, 0xb800
@@ -153,9 +147,7 @@ flip_mouse_cursor:
 	mov [es:bx], al
 
 	pop es
-	pop cx
-	pop bx
-	pop ax
+	popa
 	ret
 
 ; ------------------------------------------------------------------
@@ -168,10 +160,7 @@ flip_mouse_cursor:
 ;  cx = number of sectors to read (must be at least 1)
 ;  es:bx = output buffer
 read_sectors:
-	push ax
-	push cx
-	push bx
-	push di
+	pusha
 
 	xor di, di
 	.loop:
@@ -180,10 +169,7 @@ read_sectors:
 		add bx, 512
 		loop .loop
 
-	pop di
-	pop bx
-	pop cx
-	pop ax
+	popa
 	ret
 
 ; in:
@@ -192,9 +178,7 @@ read_sectors:
 ;  es:bx = output buffer
 ;  di = 0x0100 for write, 0x0000 for read
 modify_sector:
-	push ax
-	push cx
-	push dx
+	pusha
 	push ds
 
 	xor cx, cx
@@ -226,9 +210,7 @@ modify_sector:
 	jc .error
 
 	pop ds
-	pop dx
-	pop cx
-	pop ax
+	popa
 	ret
 
 	.error:
@@ -282,13 +264,9 @@ open_file:
 		inc di
 		inc di
 
-		push cx
-		push di
-		push si
+		pusha
 		repe cmpsb
-		pop si
-		pop di
-		pop cx
+		popa
 		je .success
 
 		add ax, FILE_MAX_SIZE
@@ -340,9 +318,7 @@ X_MAX_VALUE equ 2*COLUMNS-1
 Y_MAX_VALUE equ 4*ROWS-1
 
 mouse_handler:
-	push ax
-	push bx
-	push bp
+	pusha
 	push ds
 
 	mov ax, cs
@@ -350,12 +326,12 @@ mouse_handler:
 
 	mov bp, sp
 
-	mov bx, [bp+18] ; status
+	mov bx, [bp+2*9+10] ; status
 
 	test bl, X_OVERFLOW
 	jnz .x_end
 	.x:
-		mov ax, [bp+16] ; X
+		mov ax, [bp+2*9+8] ; X
 
 		test bl, X_NEGATIVE
 		jnz .x_negative
@@ -376,7 +352,7 @@ mouse_handler:
 	test bl, Y_OVERFLOW
 	jnz .y_end
 	.y:
-		mov ax, [bp+14] ; Y
+		mov ax, [bp+2*9+6] ; Y
 
 		test bl, Y_NEGATIVE
 		jnz .y_negative
@@ -399,9 +375,7 @@ mouse_handler:
 	mov [mouse_buttons], bl
 
 	pop ds
-	pop bp
-	pop bx
-	pop ax
+	popa
 	retf
 
 ; ------------------------------------------------------------------