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|       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|       THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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.h"

        |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