(* Release 3.10 *)
(*-------------------------------------------------------------------------*
*                                                                          *
*  P_EMUL.A - protected-mode emulator support                              *
*                                                                          *
*  COPYRIGHT (C) 1989..1992 Clarion Software Corporation.                  *
*  All Rights Reserved                                                     *
*                                                                          *
*--------------------------------------------------------------------------*)

module p_emul

auto_select = 1  (* use 8087 if one is present at run time *)

public  FIDRQQ   =  0
public  FIWRQQ   =  0

public  FIERQQ   =  0
public  FIARQQ   =  0
public  FISRQQ   =  0
public  FICRQQ   =  0

public  FJERQQ  =  0
public  FJARQQ  =  0
public  FJSRQQ  =  0
public  FJCRQQ  =  0

public  FIXRQQ  =  0

segment EMU_TEXT  (EMU_CODE,28H)
  foption 2

extrn emulate8087

oldFlags        = 22
oldCS           = 20
oldIP           = 18
oldAX           = 16
oldBX           = 14
oldBX           = 12
oldDX           = 10
oldSI           = 8
oldDI           = 6
oldDS           = 4
oldES           = 2
oldBP           = 0

e286_entry :
  push  ax
  push  bx
  push  cx
  push  dx
  push  si
  push  di
  push  ds
  push  es
  push  bp
  mov   bp,sp
  cld   (* forward string direction *)
  lds  si, [bp][oldIP]
  sub  dl, dl     (* records whether there was a segment override *)
  lodsw
  sub  al, 0D8H
  cmp  al, 8
  jae  override
decoded:
  jmp emulate8087
resume:
(* ggfb: check for another float instruction *)
  lds  si, [bp][oldIP]
  cld  (* !! it may not be clear! *)
search:
  lodsw
  cmp  al, 90H
  je   skip
  cmp  al, 9BH
  je   skip
  sub  al, 0D8H
  cmp  al, 8
  jae notanother (* seg-overrides cause not checked *)
  sub dl, dl
  jmp emulate8087 (* ax,bx,cx,dl,bp,ds,si,di must all be all valid ! *)
notanother:
  mov  sp, bp
  pop  bp
  pop  es
  pop  ds
  pop  di
  pop  si
  pop  dx
  pop  cx
  pop  bx
  pop  ax
  iret

override:
  cmp  al, 3EH-0D8H    (* ds: ? *)
  je   DSfix
  cmp  al, 26H-0D8H    (* es: ? *)
  je   ESfix
  cmp  al, 2EH-0D8H    (* cs: ? *)
  je   CSfix
  (*jmp  SSfix*)
SSfix: mov  di, ss; jmp segfix
CSfix: mov  di, ds; jmp segfix
ESfix: mov  di, [bp][oldES]; jmp segfix
DSfix: mov  di, [bp][oldDS]; (*jmp segfix*)
segfix:
  mov es, di
  lodsb      (* advance to pick up mod/r/m byte *)
  xchg  ah, al
  and  al, 7
  inc dl
  jmp emulate8087

skip:
  dec si
  jmp search

public __FloatInit:
 push bp
 mov bp,sp
 sub sp, 4

 extrn __fp_1
 call far __fp_1

 db 0FH, 01H, 66H, 0FEH;      (* smsw ds:[bp][-2] *)
 test word [bp][-2],2

(*%T auto_select*)
 jnz emulation_not_required         (* disable jump for debugging *)
(*%E*)

 mov ax, 7 ; push ax             (* push 7 *)
 mov ax, EMU_TEXT ; push ax
 mov ax, e286_entry ; push ax    (* push e286_entry *)
 push ss
 lea ax, [bp][-4]; push ax       (* push address for result *)
 extrn DOSSETVEC
 call far DOSSETVEC

emulation_not_required:

 mov sp, bp
 pop bp
 mov  bx, ss
 (*call __FloatInitInstance*)
 (*ret far 0*)

public __FloatInitInstance:

 mov ax, resume
 extrn __EmulInitInstance
 call __EmulInitInstance

 push bp
 mov bp,sp
 sub sp,2
 finit
 fstcw [bp][-2]
 fwait
 or  word [bp][-2], 0C00H
 and word [bp][-2],~001DH (* enable invalid op/underflow/overflow/divide by zero exception *)
 fldcw [bp][-2]
 extrn __FloatInitStack
 call far __FloatInitStack
 mov sp,bp
 pop bp
 ret far 0

public __FloatFinish:
  ret far 0

public __FloatMathExcepOs2 :
    (* always far called from coresig *)
    (*
       stack contains far return address to signal handler, then status word,
       then far return address to error location, the iret flags.
       This is how __math_excep likes it, so just jump there.
    *)
    extrn __math_excep
    fclex
    jmp far __math_excep

public __FloatEmulNMI:
emws_status          = 414    (* org 2, aligned. Result of comparisons *)
  push ss:[emws_status]       (* as per OS/2, status word onto stack *)
  extrn sigHandlerFPE1
  jmp far sigHandlerFPE1

public __FloatJmpSave :

st1_reg = 20
st2_reg = 30

    fld st(0), st(1)
    fstp  tbyte es:[di][st1_reg], st(0)
    fld st(0), st(2)
    fstp  tbyte es:[di][st2_reg], st(0)
    fwait
    ret  far 0

public __FloatJmpRestore :

    fld  tbyte st(0), ds:[si][st1_reg]
    fstp st(2), st(0)
    fld  tbyte st(0), ds:[si][st2_reg]
    fstp st(3), st(0)
    ret  far 0


ProcessFloat    = 14

public __FloatSave :

    fsave es:[ProcessFloat]
    ret  far 0

public __FloatRestore :

    frstor ds:[ProcessFloat]
    ret  far 0

public __FloatExecSave :
public __FloatExecRestore :
    ret  far 0

segment EMU_STATE(DATA,68H)

emuRecSize = 490

select EMU_STATE

public emuBuffer:

db  0
org emuRecSize-1

end (*P_EMUL.A*)