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//

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

//

//      gen_except.sa 3.7 1/16/92

//

//      gen_except --- FPSP routine to detect reportable exceptions

//

//      This routine compares the exception enable byte of the

//      user_fpcr on the stack with the exception status byte

//      of the user_fpsr.

//

//      Any routine which may report an exceptions must load

//      the stack frame in memory with the exceptional operand(s).

//

//      Priority for exceptions is:

//

//      Highest:        bsun

//                      snan

//                      operr

//                      ovfl

//                      unfl

//                      dz

//                      inex2

//      Lowest:         inex1

//

//      Note: The IEEE standard specifies that inex2 is to be

//      reported if ovfl occurs and the ovfl enable bit is not

//      set but the inex2 enable bit is.

//

//

//              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//      THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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.

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

        |section 8

#include "fpsp.defs"

        |xref   real_trace

        |xref   fpsp_done

        |xref   fpsp_fmt_error

exc_tbl:

        .long   bsun_exc

        .long   commonE1

        .long   commonE1

        .long   ovfl_unfl

        .long   ovfl_unfl

        .long   commonE1

        .long   commonE3

        .long   commonE3

        .long   no_match

        .global gen_except

gen_except:

        cmpib   #IDLE_SIZE-4,1(%a7)     //test for idle frame

        beq     do_check                //go handle idle frame

        cmpib   #UNIMP_40_SIZE-4,1(%a7) //test for orig unimp frame

        beqs    unimp_x                 //go handle unimp frame

        cmpib   #UNIMP_41_SIZE-4,1(%a7) //test for rev unimp frame

        beqs    unimp_x                 //go handle unimp frame

        cmpib   #BUSY_SIZE-4,1(%a7)     //if size <> $60, fmt error

        bnel    fpsp_fmt_error

        leal    BUSY_SIZE+LOCAL_SIZE(%a7),%a1 //init a1 so fpsp.h

//                                      ;equates will work

// Fix up the new busy frame with entries from the unimp frame

//

        movel   ETEMP_EX(%a6),ETEMP_EX(%a1) //copy etemp from unimp

        movel   ETEMP_HI(%a6),ETEMP_HI(%a1) //frame to busy frame

        movel   ETEMP_LO(%a6),ETEMP_LO(%a1)

        movel   CMDREG1B(%a6),CMDREG1B(%a1) //set inst in frame to unimp

        movel   CMDREG1B(%a6),%d0               //fix cmd1b to make it

        andl    #0x03c30000,%d0         //work for cmd3b

        bfextu  CMDREG1B(%a6){#13:#1},%d1       //extract bit 2

        lsll    #5,%d1

        swap    %d1

        orl     %d1,%d0                 //put it in the right place

        bfextu  CMDREG1B(%a6){#10:#3},%d1       //extract bit 3,4,5

        lsll    #2,%d1

        swap    %d1

        orl     %d1,%d0                 //put them in the right place

        movel   %d0,CMDREG3B(%a1)               //in the busy frame

//

// Or in the FPSR from the emulation with the USER_FPSR on the stack.

//

        fmovel  %FPSR,%d0

        orl     %d0,USER_FPSR(%a6)

        movel   USER_FPSR(%a6),FPSR_SHADOW(%a1) //set exc bits

        orl     #sx_mask,E_BYTE(%a1)

        bra     do_clean

//

// Frame is an unimp frame possible resulting from an fmove ,fp0

// that caused an exception

//

// a1 is modified to point into the new frame allowing fpsp equates

// to be valid.

//

unimp_x:

        cmpib   #UNIMP_40_SIZE-4,1(%a7) //test for orig unimp frame

        bnes    test_rev

        leal    UNIMP_40_SIZE+LOCAL_SIZE(%a7),%a1

        bras    unimp_con

test_rev:

        cmpib   #UNIMP_41_SIZE-4,1(%a7) //test for rev unimp frame

        bnel    fpsp_fmt_error          //if not $28 or $30

        leal    UNIMP_41_SIZE+LOCAL_SIZE(%a7),%a1

unimp_con:

//

// Fix up the new unimp frame with entries from the old unimp frame

//

        movel   CMDREG1B(%a6),CMDREG1B(%a1) //set inst in frame to unimp

//

// Or in the FPSR from the emulation with the USER_FPSR on the stack.

//

        fmovel  %FPSR,%d0

        orl     %d0,USER_FPSR(%a6)

        bra     do_clean

//

// Frame is idle, so check for exceptions reported through

// USER_FPSR and set the unimp frame accordingly.

// A7 must be incremented to the point before the

// idle fsave vector to the unimp vector.

//

do_check:

        addl    #4,%a7                  //point A7 back to unimp frame

//

// Or in the FPSR from the emulation with the USER_FPSR on the stack.

//

        fmovel  %FPSR,%d0

        orl     %d0,USER_FPSR(%a6)

//

// On a busy frame, we must clear the nmnexc bits.

//

        cmpib   #BUSY_SIZE-4,1(%a7)     //check frame type

        bnes    check_fr                //if busy, clr nmnexc

        clrw    NMNEXC(%a6)             //clr nmnexc & nmcexc

        btstb   #5,CMDREG1B(%a6)                //test for fmove out

        bnes    frame_com

        movel   USER_FPSR(%a6),FPSR_SHADOW(%a6) //set exc bits

        orl     #sx_mask,E_BYTE(%a6)

        bras    frame_com

check_fr:

        cmpb    #UNIMP_40_SIZE-4,1(%a7)

        beqs    frame_com

        clrw    NMNEXC(%a6)

frame_com:

        moveb   FPCR_ENABLE(%a6),%d0    //get fpcr enable byte

        andb    FPSR_EXCEPT(%a6),%d0    //and in the fpsr exc byte

        bfffo   %d0{#24:#8},%d1         //test for first set bit

        leal    exc_tbl,%a0             //load jmp table address

        subib   #24,%d1                 //normalize bit offset to 0-8

        movel   (%a0,%d1.w*4),%a0               //load routine address based

//                                      ;based on first enabled exc

        jmp     (%a0)                   //jump to routine

//

// Bsun is not possible in unimp or unsupp

//

bsun_exc:

        bra     do_clean

//

// The typical work to be done to the unimp frame to report an

// exception is to set the E1/E3 byte and clr the U flag.

// commonE1 does this for E1 exceptions, which are snan,

// operr, and dz.  commonE3 does this for E3 exceptions, which

// are inex2 and inex1, and also clears the E1 exception bit

// left over from the unimp exception.

//

commonE1:

        bsetb   #E1,E_BYTE(%a6)         //set E1 flag

        bra     commonE                 //go clean and exit

commonE3:

        tstb    UFLG_TMP(%a6)           //test flag for unsup/unimp state

        bnes    unsE3

uniE3:

        bsetb   #E3,E_BYTE(%a6)         //set E3 flag

        bclrb   #E1,E_BYTE(%a6)         //clr E1 from unimp

        bra     commonE

unsE3:

        tstb    RES_FLG(%a6)

        bnes    unsE3_0

unsE3_1:

        bsetb   #E3,E_BYTE(%a6)         //set E3 flag

unsE3_0:

        bclrb   #E1,E_BYTE(%a6)         //clr E1 flag

        movel   CMDREG1B(%a6),%d0

        andl    #0x03c30000,%d0         //work for cmd3b

        bfextu  CMDREG1B(%a6){#13:#1},%d1       //extract bit 2

        lsll    #5,%d1

        swap    %d1

        orl     %d1,%d0                 //put it in the right place

        bfextu  CMDREG1B(%a6){#10:#3},%d1       //extract bit 3,4,5

        lsll    #2,%d1

        swap    %d1

        orl     %d1,%d0                 //put them in the right place

        movel   %d0,CMDREG3B(%a6)               //in the busy frame

commonE:

        bclrb   #UFLAG,T_BYTE(%a6)      //clr U flag from unimp

        bra     do_clean                //go clean and exit

//

// No bits in the enable byte match existing exceptions.  Check for

// the case of the ovfl exc without the ovfl enabled, but with

// inex2 enabled.

//

no_match:

        btstb   #inex2_bit,FPCR_ENABLE(%a6) //check for ovfl/inex2 case

        beqs    no_exc                  //if clear, exit

        btstb   #ovfl_bit,FPSR_EXCEPT(%a6) //now check ovfl

        beqs    no_exc                  //if clear, exit

        bras    ovfl_unfl               //go to unfl_ovfl to determine if

//                                      ;it is an unsupp or unimp exc

// No exceptions are to be reported.  If the instruction was

// unimplemented, no FPU restore is necessary.  If it was

// unsupported, we must perform the restore.

no_exc:

        tstb    UFLG_TMP(%a6)   //test flag for unsupp/unimp state

        beqs    uni_no_exc

uns_no_exc:

        tstb    RES_FLG(%a6)    //check if frestore is needed

        bne     do_clean        //if clear, no frestore needed

uni_no_exc:

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

        fmovemx USER_FP0(%a6),%fp0-%fp3

        fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar

        unlk    %a6

        bra     finish_up

//

// Unsupported Data Type Handler:

// Ovfl:

//   An fmoveout that results in an overflow is reported this way.

// Unfl:

//   An fmoveout that results in an underflow is reported this way.

//

// Unimplemented Instruction Handler:

// Ovfl:

//   Only scosh, setox, ssinh, stwotox, and scale can set overflow in

//   this manner.

// Unfl:

//   Stwotox, setox, and scale can set underflow in this manner.

//   Any of the other Library Routines such that f(x)=x in which

//   x is an extended denorm can report an underflow exception.

//   It is the responsibility of the exception-causing exception

//   to make sure that WBTEMP is correct.

//

//   The exceptional operand is in FP_SCR1.

//

ovfl_unfl:

        tstb    UFLG_TMP(%a6)   //test flag for unsupp/unimp state

        beqs    ofuf_con

//

// The caller was from an unsupported data type trap.  Test if the

// caller set CU_ONLY.  If so, the exceptional operand is expected in

// FPTEMP, rather than WBTEMP.

//

        tstb    CU_ONLY(%a6)            //test if inst is cu-only

        beq     unsE3

//      move.w  #$fe,CU_SAVEPC(%a6)

        clrb    CU_SAVEPC(%a6)

        bsetb   #E1,E_BYTE(%a6)         //set E1 exception flag

        movew   ETEMP_EX(%a6),FPTEMP_EX(%a6)

        movel   ETEMP_HI(%a6),FPTEMP_HI(%a6)

        movel   ETEMP_LO(%a6),FPTEMP_LO(%a6)

        bsetb   #fptemp15_bit,DTAG(%a6) //set fpte15

        bclrb   #UFLAG,T_BYTE(%a6)      //clr U flag from unimp

        bra     do_clean                //go clean and exit

ofuf_con:

        moveb   (%a7),VER_TMP(%a6)      //save version number

        cmpib   #BUSY_SIZE-4,1(%a7)     //check for busy frame

        beqs    busy_fr                 //if unimp, grow to busy

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

        bnes    try_41                  //if not, test for rev frame

        moveql  #13,%d0                 //need to zero 14 lwords

        bras    ofuf_fin

try_41:

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

        bnel    fpsp_fmt_error          //if neither, exit with error

        moveql  #11,%d0                 //need to zero 12 lwords

ofuf_fin:

        clrl    (%a7)

loop1:

        clrl    -(%a7)                  //clear and dec a7

        dbra    %d0,loop1

        moveb   VER_TMP(%a6),(%a7)

        moveb   #BUSY_SIZE-4,1(%a7)             //write busy fmt word.

busy_fr:

        movel   FP_SCR1(%a6),WBTEMP_EX(%a6)     //write

        movel   FP_SCR1+4(%a6),WBTEMP_HI(%a6)   //exceptional op to

        movel   FP_SCR1+8(%a6),WBTEMP_LO(%a6)   //wbtemp

        bsetb   #E3,E_BYTE(%a6)                 //set E3 flag

        bclrb   #E1,E_BYTE(%a6)                 //make sure E1 is clear

        bclrb   #UFLAG,T_BYTE(%a6)              //clr U flag

        movel   USER_FPSR(%a6),FPSR_SHADOW(%a6)

        orl     #sx_mask,E_BYTE(%a6)

        movel   CMDREG1B(%a6),%d0               //fix cmd1b to make it

        andl    #0x03c30000,%d0         //work for cmd3b

        bfextu  CMDREG1B(%a6){#13:#1},%d1       //extract bit 2

        lsll    #5,%d1

        swap    %d1

        orl     %d1,%d0                 //put it in the right place

        bfextu  CMDREG1B(%a6){#10:#3},%d1       //extract bit 3,4,5

        lsll    #2,%d1

        swap    %d1

        orl     %d1,%d0                 //put them in the right place

        movel   %d0,CMDREG3B(%a6)               //in the busy frame

//

// Check if the frame to be restored is busy or unimp.

//** NOTE *** Bug fix for errata (0d43b #3)

// If the frame is unimp, we must create a busy frame to

// fix the bug with the nmnexc bits in cases in which they

// are set by a previous instruction and not cleared by

// the save. The frame will be unimp only if the final

// instruction in an emulation routine caused the exception

// by doing an fmove ,fp0.  The exception operand, in

// internal format, is in fptemp.

//

do_clean:

        cmpib   #UNIMP_40_SIZE-4,1(%a7)

        bnes    do_con

        moveql  #13,%d0                 //in orig, need to zero 14 lwords

        bras    do_build

do_con:

        cmpib   #UNIMP_41_SIZE-4,1(%a7)

        bnes    do_restore              //frame must be busy

        moveql  #11,%d0                 //in rev, need to zero 12 lwords

do_build:

        moveb   (%a7),VER_TMP(%a6)

        clrl    (%a7)

loop2:

        clrl    -(%a7)                  //clear and dec a7

        dbra    %d0,loop2

//

// Use a1 as pointer into new frame.  a6 is not correct if an unimp or

// busy frame was created as the result of an exception on the final

// instruction of an emulation routine.

//

// We need to set the nmcexc bits if the exception is E1. Otherwise,

// the exc taken will be inex2.

//

        leal    BUSY_SIZE+LOCAL_SIZE(%a7),%a1   //init a1 for new frame

        moveb   VER_TMP(%a6),(%a7)      //write busy fmt word

        moveb   #BUSY_SIZE-4,1(%a7)

        movel   FP_SCR1(%a6),WBTEMP_EX(%a1)     //write

        movel   FP_SCR1+4(%a6),WBTEMP_HI(%a1)   //exceptional op to

        movel   FP_SCR1+8(%a6),WBTEMP_LO(%a1)   //wbtemp

//      btst.b  #E1,E_BYTE(%a1)

//      beq.b   do_restore

        bfextu  USER_FPSR(%a6){#17:#4},%d0      //get snan/operr/ovfl/unfl bits

        bfins   %d0,NMCEXC(%a1){#4:#4}  //and insert them in nmcexc

        movel   USER_FPSR(%a6),FPSR_SHADOW(%a1) //set exc bits

        orl     #sx_mask,E_BYTE(%a1)

do_restore:

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

        fmovemx USER_FP0(%a6),%fp0-%fp3

        fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar

        frestore (%a7)+

        tstb    RES_FLG(%a6)    //RES_FLG indicates a "continuation" frame

        beq     cont

        bsr     bug1384

cont:

        unlk    %a6

//

// If trace mode enabled, then go to trace handler.  This handler

// cannot have any fp instructions.  If there are fp inst's and an

// exception has been restored into the machine then the exception

// will occur upon execution of the fp inst.  This is not desirable

// in the kernel (supervisor mode).  See MC68040 manual Section 9.3.8.

//

finish_up:

        btstb   #7,(%a7)                //test T1 in SR

        bnes    g_trace

        btstb   #6,(%a7)                //test T0 in SR

        bnes    g_trace

        bral    fpsp_done

//

// Change integer stack to look like trace stack

// The address of the instruction that caused the

// exception is already in the integer stack (is

// the same as the saved friar)

//

// If the current frame is already a 6-word stack then all

// that needs to be done is to change the vector# to TRACE.

// If the frame is only a 4-word stack (meaning we got here

// on an Unsupported data type exception), then we need to grow

// the stack an extra 2 words and get the FPIAR from the FPU.

//

g_trace:

        bftst   EXC_VEC-4(%sp){#0:#4}

        bne     g_easy

        subw    #4,%sp          // make room

        movel   4(%sp),(%sp)

        movel   8(%sp),4(%sp)

        subw    #BUSY_SIZE,%sp

        fsave   (%sp)

        fmovel  %fpiar,BUSY_SIZE+EXC_EA-4(%sp)

        frestore (%sp)

        addw    #BUSY_SIZE,%sp

g_easy:

        movew   #TRACE_VEC,EXC_VEC-4(%a7)

        bral    real_trace

//

//  This is a work-around for hardware bug 1384.

//

bug1384:

        link    %a5,#0

        fsave   -(%sp)

        cmpib   #0x41,(%sp)     // check for correct frame

        beq     frame_41

        bgt     nofix           // if more advanced mask, do nada

frame_40:

        tstb    1(%sp)          // check to see if idle

        bne     notidle

idle40:

        clrl    (%sp)           // get rid of old fsave frame

        movel  %d1,USER_D1(%a6)  // save d1

        movew   #8,%d1          // place unimp frame instead

loop40: clrl    -(%sp)

        dbra    %d1,loop40

        movel  USER_D1(%a6),%d1  // restore d1

        movel   #0x40280000,-(%sp)

        frestore (%sp)+

        unlk    %a5

        rts

frame_41:

        tstb    1(%sp)          // check to see if idle

        bne     notidle

idle41:

        clrl    (%sp)           // get rid of old fsave frame

        movel  %d1,USER_D1(%a6)  // save d1

        movew   #10,%d1         // place unimp frame instead

loop41: clrl    -(%sp)

        dbra    %d1,loop41

        movel  USER_D1(%a6),%d1  // restore d1

        movel   #0x41300000,-(%sp)

        frestore (%sp)+

        unlk    %a5

        rts

notidle:

        bclrb   #etemp15_bit,-40(%a5)

        frestore (%sp)+

        unlk    %a5

        rts

nofix:

        frestore (%sp)+

        unlk    %a5

        rts

        |end