Subversion Repositories openrisc_2011-10-31

//

//      $Id: x_fline.S,v 1.2 2001-09-27 12:01:22 chris Exp $

//

//      x_fline.sa 3.3 1/10/91

//

//      fpsp_fline --- FPSP handler for fline exception

//

//      First determine if the exception is one of the unimplemented

//      floating point instructions.  If so, let fpsp_unimp handle it.

//      Next, determine if the instruction is an fmovecr with a non-zero

//       field.  If so, handle here and return.  Otherwise, it

//      must be a real F-line exception.

//

//              Copyright (C) Motorola, Inc. 1990

//                      All Rights Reserved

//

//      THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA

//      The copyright notice above does not evidence any

//      actual or intended publication of such source code.

X_FLINE:        //idnt    2,1 | Motorola 040 Floating Point Software Package

        |section        8

#include "fpsp.defs"

        |xref   real_fline

        |xref   fpsp_unimp

        |xref   uni_2

        |xref   mem_read

        |xref   fpsp_fmt_error

        .global fpsp_fline

fpsp_fline:

//

//      check for unimplemented vector first.  Use EXC_VEC-4 because

//      the equate is valid only after a 'link a6' has pushed one more

//      long onto the stack.

//

        cmpw    #UNIMP_VEC,EXC_VEC-4(%a7)

        beql    fpsp_unimp

//

//      fmovecr with non-zero  handling here

//

        subl    #4,%a7          //4 accounts for 2-word difference

//                              ;between six word frame (unimp) and

//                              ;four word frame

        link    %a6,#-LOCAL_SIZE

        fsave   -(%a7)

        moveml  %d0-%d1/%a0-%a1,USER_DA(%a6)

        moveal  EXC_PC+4(%a6),%a0       //get address of fline instruction

        leal    L_SCR1(%a6),%a1 //use L_SCR1 as scratch

        movel   #4,%d0

        addl    #4,%a6          //to offset the sub.l #4,a7 above so that

//                              ;a6 can point correctly to the stack frame

//                              ;before branching to mem_read

        bsrl    mem_read

        subl    #4,%a6

        movel   L_SCR1(%a6),%d0 //d0 contains the fline and command word

        bfextu  %d0{#4:#3},%d1  //extract coprocessor id

        cmpib   #1,%d1          //check if cpid=1

        bne     not_mvcr        //exit if not

        bfextu  %d0{#16:#6},%d1

        cmpib   #0x17,%d1               //check if it is an FMOVECR encoding

        bne     not_mvcr

//                              ;if an FMOVECR instruction, fix stack

//                              ;and go to FPSP_UNIMP

fix_stack:

        cmpib   #VER_40,(%a7)   //test for orig unimp frame

        bnes    ck_rev

        subl    #UNIMP_40_SIZE-4,%a7 //emulate an orig fsave

        moveb   #VER_40,(%a7)

        moveb   #UNIMP_40_SIZE-4,1(%a7)

        clrw    2(%a7)

        bras    fix_con

ck_rev:

        cmpib   #VER_41,(%a7)   //test for rev unimp frame

        bnel    fpsp_fmt_error  //if not $40 or $41, exit with error

        subl    #UNIMP_41_SIZE-4,%a7 //emulate a rev fsave

        moveb   #VER_41,(%a7)

        moveb   #UNIMP_41_SIZE-4,1(%a7)

        clrw    2(%a7)

fix_con:

        movew   EXC_SR+4(%a6),EXC_SR(%a6) //move stacked sr to new position

        movel   EXC_PC+4(%a6),EXC_PC(%a6) //move stacked pc to new position

        fmovel  EXC_PC(%a6),%FPIAR //point FPIAR to fline inst

        movel   #4,%d1

        addl    %d1,EXC_PC(%a6) //increment stacked pc value to next inst

        movew   #0x202c,EXC_VEC(%a6) //reformat vector to unimp

        clrl    EXC_EA(%a6)     //clear the EXC_EA field

        movew   %d0,CMDREG1B(%a6) //move the lower word into CMDREG1B

        clrl    E_BYTE(%a6)

        bsetb   #UFLAG,T_BYTE(%a6)

        moveml  USER_DA(%a6),%d0-%d1/%a0-%a1 //restore data registers

        bral    uni_2

not_mvcr:

        moveml  USER_DA(%a6),%d0-%d1/%a0-%a1 //restore data registers

        frestore (%a7)+

        unlk    %a6

        addl    #4,%a7

        bral    real_fline

        |end