From 41d6a33d31d348563a9c97b7cf25752e8e64f599 Mon Sep 17 00:00:00 2001
From: Jeffrey Armstrong <jeff@approximatrix.com>
Date: Wed, 13 Nov 2024 13:51:48 -0500
Subject: Added bus width detection that appears to work on an 8088.

---
 asm/386q.asm | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 52 insertions(+), 9 deletions(-)

(limited to 'asm')

diff --git a/asm/386q.asm b/asm/386q.asm
index 4496d66..bf58033 100644
--- a/asm/386q.asm
+++ b/asm/386q.asm
@@ -1,3 +1,14 @@
+        ; Results:
+        ; 0 - 8088
+        ; 1 - 8086
+        ; 2 - V20
+        ; 3 - V30
+        ; 4 - 80188
+        ; 5 - 80186
+        ; 6 - 80286
+        ; 7 - 80386+
+        
+        
         push bp
         mov bp, sp
         
@@ -13,8 +24,8 @@
         cmp ax, 0xf000 ;0f000h
         je lessthantwoeightsix
         
-        ; marked as 286 (2)
-        mov dl, 2
+        ; marked as 286 (6)
+        mov dl, 6
         
         mov ax, 0x7000 ;7000h
         push ax
@@ -25,24 +36,25 @@
         and ax, 0x7000 ;7000h
         jz alldone
         
-        ; mark as 386 (3)
+        ; mark as 386 (7)
         inc dl
         
         jmp alldone
         
 lessthantwoeightsix:
         
-        mov dl, 1
+        ; Mark as 80188 (4)
+        mov dl, 4
         
         mov al, 0xff ;0ffh
         mov cl, 0x21 ;21h
         shr al, cl
         
         ; if the shift leaves zero, it's a 8088 class cpu, else 80186/88
-        jnz alldone
+        jnz buswidth
         
-        ; Lets see if we have a V20/V30 (V)
-        mov dl, 0x56 ;056h
+        ; Lets see if we have a V20/V30 (2)
+        mov dl, 2
 
         sti
         push si
@@ -55,11 +67,42 @@ lessthantwoeightsix:
         pop si
         
         or cx, cx
-        jz alldone
+        jz buswidth
         
-        ; mark as a 8088/8086 (0)
+        ; mark as a 8088/8086 (1)
         mov dl, 0
         
+buswidth:
+        
+        ; we are destroying es now, must be restored later
+        push cs
+        pop es
+        std
+        
+        ; The 99 _must_ be replaced with the true offset of qqend
+        mov di, 99 ; OFFSET qqend ;99
+        
+        ;set up al and cx: 0xfb is the 'sti' instruction
+        mov al, 0xfb
+        mov cx, 3
+        
+        ; disable interrupts
+        cli
+        rep stosb
+        
+        cld
+        nop
+        nop
+        nop
+        inc dx
+        nop
+qqend:
+        sti
+        
+        ; ES must be restored
+        push ds
+        pop es
+        
 alldone:
         ; store in ax
         xor dh, dh
-- 
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