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|       x_snan.sa 3.3 7/1/91

|

| fpsp_snan --- FPSP handler for signalling NAN exception

|

| SNAN for float -> integer conversions (integer conversion of

| an SNAN) is a non-maskable run-time exception.

|

| For trap disabled the 040 does the following:

| If the dest data format is s, d, or x, then the SNAN bit in the NAN

| is set to one and the resulting non-signaling NAN (truncated if

| necessary) is transferred to the dest.  If the dest format is b, w,

| or l, then garbage is written to the dest (actually the upper 32 bits

| of the mantissa are sent to the integer unit).

|

| For trap enabled the 040 does the following:

| If the inst is move_out, then the results are the same as for trap

| disabled with the exception posted.  If the instruction is not move_

| out, the dest. is not modified, and the exception is posted.

|

|               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|       THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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_SNAN: |idnt    2,1 | Motorola 040 Floating Point Software Package

        |section        8

        .include "fpsp.h"

        |xref   get_fline

        |xref   mem_write

        |xref   real_snan

        |xref   real_inex

        |xref   fpsp_done

        |xref   reg_dest

        .global fpsp_snan

fpsp_snan:

        link            %a6,#-LOCAL_SIZE

        fsave           -(%a7)

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

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

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

|

| Check if trap enabled

|

        btstb           #snan_bit,FPCR_ENABLE(%a6)

        bnes            ena             |If enabled, then branch

        bsrl            move_out        |else SNAN disabled

|

| It is possible to have an inex1 exception with the

| snan.  If the inex enable bit is set in the FPCR, and either

| inex2 or inex1 occurred, we must clean up and branch to the

| real inex handler.

|

ck_inex:

        moveb   FPCR_ENABLE(%a6),%d0

        andb    FPSR_EXCEPT(%a6),%d0

        andib   #0x3,%d0

        beq     end_snan

|

| Inexact enabled and reported, and we must take an inexact exception.

|

take_inex:

        moveb           #INEX_VEC,EXC_VEC+1(%a6)

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

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

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

        frestore        (%a7)+

        unlk            %a6

        bral            real_inex

|

| SNAN is enabled.  Check if inst is move_out.

| Make any corrections to the 040 output as necessary.

|

ena:

        btstb           #5,CMDREG1B(%a6) |if set, inst is move out

        beq             not_out

        bsrl            move_out

report_snan:

        moveb           (%a7),VER_TMP(%a6)

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

        bnes            ck_rev

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

        bras            rep_con

ck_rev:

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

rep_con:

        clrl            (%a7)

loop1:

        clrl            -(%a7)          |clear and dec a7

        dbra            %d0,loop1

        moveb           VER_TMP(%a6),(%a7) |format a busy frame

        moveb           #BUSY_SIZE-4,1(%a7)

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

        orl             #sx_mask,E_BYTE(%a6)

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

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

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

        frestore        (%a7)+

        unlk            %a6

        bral            real_snan

|

| Exit snan handler by expanding the unimp frame into a busy frame

|

end_snan:

        bclrb           #E1,E_BYTE(%a6)

        moveb           (%a7),VER_TMP(%a6)

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

        bnes            ck_rev2

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

        bras            rep_con2

ck_rev2:

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

rep_con2:

        clrl            (%a7)

loop2:

        clrl            -(%a7)          |clear and dec a7

        dbra            %d0,loop2

        moveb           VER_TMP(%a6),(%a7) |format a busy frame

        moveb           #BUSY_SIZE-4,1(%a7) |write busy size

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

        orl             #sx_mask,E_BYTE(%a6)

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

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

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

        frestore        (%a7)+

        unlk            %a6

        bral            fpsp_done

|

| Move_out

|

move_out:

        movel           EXC_EA(%a6),%a0 |get  from exc frame

        bfextu          CMDREG1B(%a6){#3:#3},%d0 |move rx field to d0{2:0}

        cmpil           #0,%d0          |check for long

        beqs            sto_long        |branch if move_out long

        cmpil           #4,%d0          |check for word

        beqs            sto_word        |branch if move_out word

        cmpil           #6,%d0          |check for byte

        beqs            sto_byte        |branch if move_out byte

|

| Not byte, word or long

|

        rts

|

| Get the 32 most significant bits of etemp mantissa

|

sto_long:

        movel           ETEMP_HI(%a6),%d1

        movel           #4,%d0          |load byte count

|

| Set signalling nan bit

|

        bsetl           #30,%d1

|

| Store to the users destination address

|

        tstl            %a0             |check if  is 0

        beqs            wrt_dn          |destination is a data register

        movel           %d1,-(%a7)      |move the snan onto the stack

        movel           %a0,%a1         |load dest addr into a1

        movel           %a7,%a0         |load src addr of snan into a0

        bsrl            mem_write       |write snan to user memory

        movel           (%a7)+,%d1      |clear off stack

        rts

|

| Get the 16 most significant bits of etemp mantissa

|

sto_word:

        movel           ETEMP_HI(%a6),%d1

        movel           #2,%d0          |load byte count

|

| Set signalling nan bit

|

        bsetl           #30,%d1

|

| Store to the users destination address

|

        tstl            %a0             |check if  is 0

        beqs            wrt_dn          |destination is a data register

        movel           %d1,-(%a7)      |move the snan onto the stack

        movel           %a0,%a1         |load dest addr into a1

        movel           %a7,%a0         |point to low word

        bsrl            mem_write       |write snan to user memory

        movel           (%a7)+,%d1      |clear off stack

        rts

|

| Get the 8 most significant bits of etemp mantissa

|

sto_byte:

        movel           ETEMP_HI(%a6),%d1

        movel           #1,%d0          |load byte count

|

| Set signalling nan bit

|

        bsetl           #30,%d1

|

| Store to the users destination address

|

        tstl            %a0             |check if  is 0

        beqs            wrt_dn          |destination is a data register

        movel           %d1,-(%a7)      |move the snan onto the stack

        movel           %a0,%a1         |load dest addr into a1

        movel           %a7,%a0         |point to source byte

        bsrl            mem_write       |write snan to user memory

        movel           (%a7)+,%d1      |clear off stack

        rts

|

|       wrt_dn --- write to a data register

|

|       We get here with D1 containing the data to write and D0 the

|       number of bytes to write: 1=byte,2=word,4=long.

|

wrt_dn:

        movel           %d1,L_SCR1(%a6) |data

        movel           %d0,-(%a7)      |size

        bsrl            get_fline       |returns fline word in d0

        movel           %d0,%d1

        andil           #0x7,%d1                |d1 now holds register number

        movel           (%sp)+,%d0      |get original size

        cmpil           #4,%d0

        beqs            wrt_long

        cmpil           #2,%d0

        bnes            wrt_byte

wrt_word:

        orl             #0x8,%d1

        bral            reg_dest

wrt_long:

        orl             #0x10,%d1

        bral            reg_dest

wrt_byte:

        bral            reg_dest

|

| Check if it is a src nan or dst nan

|

not_out:

        movel           DTAG(%a6),%d0

        bfextu          %d0{#0:#3},%d0  |isolate dtag in lsbs

        cmpib           #3,%d0          |check for nan in destination

        bnes            issrc           |destination nan has priority

dst_nan:

        btstb           #6,FPTEMP_HI(%a6) |check if dest nan is an snan

        bnes            issrc           |no, so check source for snan

        movew           FPTEMP_EX(%a6),%d0

        bras            cont

issrc:

        movew           ETEMP_EX(%a6),%d0

cont:

        btstl           #15,%d0         |test for sign of snan

        beqs            clr_neg

        bsetb           #neg_bit,FPSR_CC(%a6)

        bra             report_snan

clr_neg:

        bclrb           #neg_bit,FPSR_CC(%a6)

        bra             report_snan

        |end