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//

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

//

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//      THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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

        |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