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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|       THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA 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 <ea>,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 <ea>,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