;***************************************************************************
;
; PostScript interpreter file "postasm.a" - assembler routines (Amiga)
; (C) Adrian Aylward 1989, 1991
;
; This file contains the assembler support routines for the main program.
; It is Lattice specific.
;
;***************************************************************************

        include "exec/execbase.i"
        include "exec/tasks.i"
        include "exec/funcdef.i"
        include "exec/exec_lib.i"
        include "libraries/dos.i"

;***************************************************************************
;
; The text segment
;
;***************************************************************************

        csect   text,0

        xref    sigint
        xref    sigfpe

        xdef    insertbreak
        xdef    deletebreak
        xdef    insertftrap
        xdef    deleteftrap

;***************************************************************************
;
; Insert the break exception handler
;
;***************************************************************************

insertbreak:
        move.l  4,a0                    ; Get ExecBase
        move.l  ThisTask(a0),a0         ; Locate our task
        move.l  TC_EXCEPTCODE(a0),sxcode  ; Save old hanmdler
        move.l  #hbreak,TC_EXCEPTCODE(a0) ; Insert new handler
        rts

;***************************************************************************
;
; Delete the break exception handler
;
;***************************************************************************

deletebreak:
        move.l  4,a0                    ; Get ExecBase
        move.l  ThisTask(a0),a0         ; Locate our task
        move.l  sxcode,TC_EXCEPTCODE(a0)  ; Restore old hanmdler
        rts

;***************************************************************************
;
; The break exception handler
;
;***************************************************************************

hbreak:
        btst    #SIGBREAKB_CTRL_C,d0    ; if this a CTRL/C
        beq.s   hb1
        movem.l d0/d1/a0/a1,-(sp)
        moveq   #1,d0
        move.l  d0,-(sp)
        jsr     sigint                  ; signal interrupt
        addq.l  #4,sp
        movem.l (sp)+,d0/d1/a0/a1
hb1:    rts

;***************************************************************************
;
; Insert the floating point trap handler
;
;***************************************************************************

insertftrap:
        move.l  a6,-(sp)
        move.l  4,a6                    ; Get ExecBase
        btst    #4,AttnFlags+1(a6)      ; See if we have an FPU
        beq.s   if1
        move.l  ThisTask(a6),a0         ; Locate our task
        move.l  TC_TRAPCODE(a0),stcode  ; Save old hanmdler
        move.l  #sftrap,TC_TRAPCODE(a0) ; Insert new handler
        fmove.l fpcr,d0
        move.l  d0,sfpcr                ; Save fpcr
        or.w    #$fd90,d0               ; Set trap flags in fpcr
        fmove.l d0,fpcr
if1:    move.l  (sp)+,a6
        rts

;***************************************************************************
;
; Delete the floating point trap handler
;
;***************************************************************************

deleteftrap:
        move.l  a6,-(sp)
        move.l  4,a6                    ; Get ExecBase
        btst    #4,AttnFlags+1(a6)      ; See if we have an FPU
        beq.s   df1
        move.l  sfpcr,d0                ; Restore fpcr
        fmove.l d0,fpcr
        move.l  ThisTask(a6),a0         ; Locate our task
        move.l  stcode,TC_TRAPCODE(a0)  ; Restore old hanmdler
df1:    move.l  (sp)+,a6
        rts

;***************************************************************************
;
; The floating point trap handler
;
;***************************************************************************

sftrap: cmp.l   #48,(sp)                ; fp traps are 48 - 54
        blo.s   ht1
        cmp.l   #54,(sp)
        bls.s   ht2
ht1:    move.l  stcode,-(sp)            ; not fp, jump to old handler
        rts

ht2:    move.l  d0,-(sp)
        fsave   -(a7)                   ; save FPU internal state
        move.b  0(a7),d0                ; first byte of FPU state frame
        beq.s   ht3                     ; branch on null state frame

        moveq   #0,D0
        move.b  1(a7),d0                ; load state frame size (in bytes)
        bset    #3,0(a7,d0.l)           ; set FPU exception pending bit (27)

ht3:    frestore (a7)+                  ; restore FPU internal state
        addq.l  #4,sp                   ; discard trap number
        move.l  #uftrap,2(sp)           ; update pc with user trap handler
        rte                             ; return to user state, enter trap

uftrap: move.l  4,a6                    ; Get ExecBase
        jsr     sigfpe                  ; signal fp error, no return

;***************************************************************************
;
; The data segment (bss)
;
;***************************************************************************

        CSECT   __MERGED,2        ; BSS

sxcode: ds.b    4                 ; Saved exception code
stcode: ds.b    4                 ; Saved trap code

sfpcr:  ds.b    4                 ; Saved fpcr

        end

; End of file "postasm.a"