Slightly simpler to use interface to simple_pm_call

Clean up the interface to simple_pm_call so we generally can avoid a
bunch of push/call/pop/ret boilerplate.

diff --git a/bcopy32.inc b/bcopy32.inc
index 056f29b..b62d3ac 100644 (file)
--- a/bcopy32.inc
+++ b/bcopy32.inc
@@ -95,7 +95,7 @@ bcopy_gdt_size:       equ $-bcopy_gdt
 ;      EDI     - first byte after target
 ;
 bcopy:         pushad
-               mov bx,pm_bcopy
+               push word pm_bcopy
                call simple_pm_call
                popad
                add edi,ecx
@@ -112,15 +112,20 @@ bcopy:            pushad
 ; for the duration of the routine.  Don't run for too long at a time.
 ;
 ; Inputs:
-;      BX      - routine to execute
-;      ECX, EDX, EBP, ESI and EDI passed to the called routine
+;      On stack        - pm entrypoint
+;      EAX, EBP preserved until real-mode exit
+;      EBX, ECX, EDX, ESI and EDI passed to the called routine
 ;
 ; Outputs:
-;      EAX, EBX destroyed
+;      EAX, EBP restored from real-mode entry
 ;      All other registers as returned from called function
+;      PM entrypoint cleaned off stack
 ;
 simple_pm_call:
-               pushf                   ; Saves, among others, the IF flag
+               push eax
+               push ebp
+               mov bp,sp
+               pushfd                  ; Saves, among others, the IF flag
                push ds
                push es
                push fs
@@ -165,14 +170,14 @@ simple_pm_call:
                xor ax,ax               ; it something that it can use...
                lldt ax                 ; (sigh)
 
-               call bx                 ; Call actual routine
+               call [bp+2*4+2]         ; Call actual routine
 
 .exit:
                mov ax,PM_DS16_RM       ; "Real-mode-like" data segment
                mov es,ax
                mov ds,ax
 
-               pop bx                  ; Previous value for ss
+               pop bp                  ; Previous value for ss
 
                mov eax,cr0
                and al,~1
@@ -180,15 +185,17 @@ simple_pm_call:
                jmp 0:.in_rm
 
 .in_rm:                ; Back in real mode
-               mov ss,bx
+               mov ss,bp
                pop gs
                pop fs
                pop es
                pop ds
                call disable_a20
 
-               popf                    ; Re-enables interrupts
-               ret
+               popfd                   ; Re-enables interrupts
+               pop ebp
+               pop eax
+               ret 2                   ; Drops the pm entry
 
 ;
 ; pm_bcopy: