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[/] [or1k_old/] [trunk/] [rc203soc/] [sw/] [uClinux/] [arch/] [m68k/] [fpsp040/] [x_snan.S] - Blame information for rev 1782

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Line No. Rev Author Line
1 1623 jcastillo
|
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|       x_snan.sa 3.3 7/1/91
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|
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| fpsp_snan --- FPSP handler for signalling NAN exception
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|
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| SNAN for float -> integer conversions (integer conversion of
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| an SNAN) is a non-maskable run-time exception.
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|
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| For trap disabled the 040 does the following:
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| If the dest data format is s, d, or x, then the SNAN bit in the NAN
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| is set to one and the resulting non-signaling NAN (truncated if
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| necessary) is transferred to the dest.  If the dest format is b, w,
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| or l, then garbage is written to the dest (actually the upper 32 bits
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| of the mantissa are sent to the integer unit).
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|
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| For trap enabled the 040 does the following:
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| If the inst is move_out, then the results are the same as for trap
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| disabled with the exception posted.  If the instruction is not move_
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| out, the dest. is not modified, and the exception is posted.
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|
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|               Copyright (C) Motorola, Inc. 1990
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|                       All Rights Reserved
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|
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|       THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
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|       The copyright notice above does not evidence any
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|       actual or intended publication of such source code.
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X_SNAN: |idnt    2,1 | Motorola 040 Floating Point Software Package
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        |section        8
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        .include "fpsp.h"
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        |xref   get_fline
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        |xref   mem_write
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        |xref   real_snan
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        |xref   real_inex
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        |xref   fpsp_done
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        |xref   reg_dest
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        .global fpsp_snan
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fpsp_snan:
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        link            %a6,#-LOCAL_SIZE
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        fsave           -(%a7)
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        moveml          %d0-%d1/%a0-%a1,USER_DA(%a6)
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        fmovemx %fp0-%fp3,USER_FP0(%a6)
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        fmoveml %fpcr/%fpsr/%fpiar,USER_FPCR(%a6)
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|
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| Check if trap enabled
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|
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        btstb           #snan_bit,FPCR_ENABLE(%a6)
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        bnes            ena             |If enabled, then branch
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        bsrl            move_out        |else SNAN disabled
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|
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| It is possible to have an inex1 exception with the
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| snan.  If the inex enable bit is set in the FPCR, and either
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| inex2 or inex1 occurred, we must clean up and branch to the
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| real inex handler.
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|
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ck_inex:
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        moveb   FPCR_ENABLE(%a6),%d0
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        andb    FPSR_EXCEPT(%a6),%d0
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        andib   #0x3,%d0
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        beq     end_snan
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|
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| Inexact enabled and reported, and we must take an inexact exception.
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|
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take_inex:
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        moveb           #INEX_VEC,EXC_VEC+1(%a6)
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        moveml          USER_DA(%a6),%d0-%d1/%a0-%a1
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        fmovemx USER_FP0(%a6),%fp0-%fp3
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        fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
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        frestore        (%a7)+
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        unlk            %a6
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        bral            real_inex
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|
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| SNAN is enabled.  Check if inst is move_out.
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| Make any corrections to the 040 output as necessary.
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|
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ena:
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        btstb           #5,CMDREG1B(%a6) |if set, inst is move out
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        beq             not_out
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        bsrl            move_out
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report_snan:
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        moveb           (%a7),VER_TMP(%a6)
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        cmpib           #VER_40,(%a7)   |test for orig unimp frame
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        bnes            ck_rev
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        moveql          #13,%d0         |need to zero 14 lwords
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        bras            rep_con
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ck_rev:
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        moveql          #11,%d0         |need to zero 12 lwords
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rep_con:
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        clrl            (%a7)
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loop1:
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        clrl            -(%a7)          |clear and dec a7
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        dbra            %d0,loop1
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        moveb           VER_TMP(%a6),(%a7) |format a busy frame
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        moveb           #BUSY_SIZE-4,1(%a7)
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        movel           USER_FPSR(%a6),FPSR_SHADOW(%a6)
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        orl             #sx_mask,E_BYTE(%a6)
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        moveml          USER_DA(%a6),%d0-%d1/%a0-%a1
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        fmovemx USER_FP0(%a6),%fp0-%fp3
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        fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
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        frestore        (%a7)+
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        unlk            %a6
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        bral            real_snan
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|
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| Exit snan handler by expanding the unimp frame into a busy frame
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|
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end_snan:
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        bclrb           #E1,E_BYTE(%a6)
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        moveb           (%a7),VER_TMP(%a6)
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        cmpib           #VER_40,(%a7)   |test for orig unimp frame
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        bnes            ck_rev2
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        moveql          #13,%d0         |need to zero 14 lwords
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        bras            rep_con2
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ck_rev2:
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        moveql          #11,%d0         |need to zero 12 lwords
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rep_con2:
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        clrl            (%a7)
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loop2:
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        clrl            -(%a7)          |clear and dec a7
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        dbra            %d0,loop2
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        moveb           VER_TMP(%a6),(%a7) |format a busy frame
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        moveb           #BUSY_SIZE-4,1(%a7) |write busy size
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        movel           USER_FPSR(%a6),FPSR_SHADOW(%a6)
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        orl             #sx_mask,E_BYTE(%a6)
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        moveml          USER_DA(%a6),%d0-%d1/%a0-%a1
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        fmovemx USER_FP0(%a6),%fp0-%fp3
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        fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
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        frestore        (%a7)+
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        unlk            %a6
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        bral            fpsp_done
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|
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| Move_out
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|
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move_out:
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        movel           EXC_EA(%a6),%a0 |get  from exc frame
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        bfextu          CMDREG1B(%a6){#3:#3},%d0 |move rx field to d0{2:0}
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        cmpil           #0,%d0          |check for long
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        beqs            sto_long        |branch if move_out long
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        cmpil           #4,%d0          |check for word
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        beqs            sto_word        |branch if move_out word
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        cmpil           #6,%d0          |check for byte
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        beqs            sto_byte        |branch if move_out byte
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|
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| Not byte, word or long
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|
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        rts
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|
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| Get the 32 most significant bits of etemp mantissa
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|
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sto_long:
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        movel           ETEMP_HI(%a6),%d1
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        movel           #4,%d0          |load byte count
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|
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| Set signalling nan bit
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|
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        bsetl           #30,%d1
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|
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| Store to the users destination address
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|
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        tstl            %a0             |check if  is 0
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        beqs            wrt_dn          |destination is a data register
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        movel           %d1,-(%a7)      |move the snan onto the stack
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        movel           %a0,%a1         |load dest addr into a1
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        movel           %a7,%a0         |load src addr of snan into a0
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        bsrl            mem_write       |write snan to user memory
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        movel           (%a7)+,%d1      |clear off stack
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        rts
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|
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| Get the 16 most significant bits of etemp mantissa
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|
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sto_word:
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        movel           ETEMP_HI(%a6),%d1
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        movel           #2,%d0          |load byte count
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|
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| Set signalling nan bit
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|
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        bsetl           #30,%d1
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|
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| Store to the users destination address
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|
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        tstl            %a0             |check if  is 0
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        beqs            wrt_dn          |destination is a data register
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        movel           %d1,-(%a7)      |move the snan onto the stack
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        movel           %a0,%a1         |load dest addr into a1
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        movel           %a7,%a0         |point to low word
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        bsrl            mem_write       |write snan to user memory
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        movel           (%a7)+,%d1      |clear off stack
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        rts
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|
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| Get the 8 most significant bits of etemp mantissa
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|
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sto_byte:
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        movel           ETEMP_HI(%a6),%d1
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        movel           #1,%d0          |load byte count
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|
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| Set signalling nan bit
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|
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        bsetl           #30,%d1
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|
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| Store to the users destination address
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|
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        tstl            %a0             |check if  is 0
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        beqs            wrt_dn          |destination is a data register
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        movel           %d1,-(%a7)      |move the snan onto the stack
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        movel           %a0,%a1         |load dest addr into a1
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        movel           %a7,%a0         |point to source byte
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        bsrl            mem_write       |write snan to user memory
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        movel           (%a7)+,%d1      |clear off stack
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        rts
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|
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|       wrt_dn --- write to a data register
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|
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|       We get here with D1 containing the data to write and D0 the
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|       number of bytes to write: 1=byte,2=word,4=long.
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|
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wrt_dn:
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        movel           %d1,L_SCR1(%a6) |data
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        movel           %d0,-(%a7)      |size
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        bsrl            get_fline       |returns fline word in d0
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        movel           %d0,%d1
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        andil           #0x7,%d1                |d1 now holds register number
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        movel           (%sp)+,%d0      |get original size
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        cmpil           #4,%d0
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        beqs            wrt_long
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        cmpil           #2,%d0
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        bnes            wrt_byte
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wrt_word:
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        orl             #0x8,%d1
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        bral            reg_dest
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wrt_long:
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        orl             #0x10,%d1
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        bral            reg_dest
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wrt_byte:
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        bral            reg_dest
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|
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| Check if it is a src nan or dst nan
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|
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not_out:
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        movel           DTAG(%a6),%d0
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        bfextu          %d0{#0:#3},%d0  |isolate dtag in lsbs
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        cmpib           #3,%d0          |check for nan in destination
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        bnes            issrc           |destination nan has priority
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dst_nan:
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        btstb           #6,FPTEMP_HI(%a6) |check if dest nan is an snan
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        bnes            issrc           |no, so check source for snan
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        movew           FPTEMP_EX(%a6),%d0
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        bras            cont
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issrc:
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        movew           ETEMP_EX(%a6),%d0
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cont:
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        btstl           #15,%d0         |test for sign of snan
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        beqs            clr_neg
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        bsetb           #neg_bit,FPSR_CC(%a6)
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        bra             report_snan
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clr_neg:
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        bclrb           #neg_bit,FPSR_CC(%a6)
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        bra             report_snan
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        |end

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