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//

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

//

//      x_store.sa 3.2 1/24/91

//

//      store --- store operand to memory or register

//

//      Used by underflow and overflow handlers.

//

//      a6 = points to fp value to be stored.

//

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//      THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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

        |section        8

fpreg_mask:

        .byte   0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01

#include "fpsp.defs"

        |xref   mem_write

        |xref   get_fline

        |xref   g_opcls

        |xref   g_dfmtou

        |xref   reg_dest

        .global dest_ext

        .global dest_dbl

        .global dest_sgl

        .global store

store:

        btstb   #E3,E_BYTE(%a6)

        beqs    E1_sto

E3_sto:

        movel   CMDREG3B(%a6),%d0

        bfextu  %d0{#6:#3},%d0          //isolate dest. reg from cmdreg3b

sto_fp:

        lea     fpreg_mask,%a1

        moveb   (%a1,%d0.w),%d0         //convert reg# to dynamic register mask

        tstb    LOCAL_SGN(%a0)

        beqs    is_pos

        bsetb   #sign_bit,LOCAL_EX(%a0)

is_pos:

        fmovemx (%a0),%d0               //move to correct register

//

//      if fp0-fp3 is being modified, we must put a copy

//      in the USER_FPn variable on the stack because all exception

//      handlers restore fp0-fp3 from there.

//

        cmpb    #0x80,%d0

        bnes    not_fp0

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

        rts

not_fp0:

        cmpb    #0x40,%d0

        bnes    not_fp1

        fmovemx %fp1-%fp1,USER_FP1(%a6)

        rts

not_fp1:

        cmpb    #0x20,%d0

        bnes    not_fp2

        fmovemx %fp2-%fp2,USER_FP2(%a6)

        rts

not_fp2:

        cmpb    #0x10,%d0

        bnes    not_fp3

        fmovemx %fp3-%fp3,USER_FP3(%a6)

        rts

not_fp3:

        rts

E1_sto:

        bsrl    g_opcls         //returns opclass in d0

        cmpib   #3,%d0

        beq     opc011          //branch if opclass 3

        movel   CMDREG1B(%a6),%d0

        bfextu  %d0{#6:#3},%d0  //extract destination register

        bras    sto_fp

opc011:

        bsrl    g_dfmtou        //returns dest format in d0

//                              ;ext=00, sgl=01, dbl=10

        movel   %a0,%a1         //save source addr in a1

        movel   EXC_EA(%a6),%a0 //get the address

        cmpil   #0,%d0          //if dest format is extended

        beq     dest_ext        //then branch

        cmpil   #1,%d0          //if dest format is single

        beq     dest_sgl        //then branch

//

//      fall through to dest_dbl

//

//

//      dest_dbl --- write double precision value to user space

//

//Input

//      a0 -> destination address

//      a1 -> source in extended precision

//Output

//      a0 -> destroyed

//      a1 -> destroyed

//      d0 -> 0

//

//Changes extended precision to double precision.

// Note: no attempt is made to round the extended value to double.

//      dbl_sign = ext_sign

//      dbl_exp = ext_exp - $3fff(ext bias) + $7ff(dbl bias)

//      get rid of ext integer bit

//      dbl_mant = ext_mant{62:12}

//

//              ---------------   ---------------    ---------------

//  extended ->  |s|    exp    |   |1| ms mant   |    | ls mant     |

//              ---------------   ---------------    ---------------

//               95         64    63 62       32      31     11   0

//                                   |                       |

//                                   |                       |

//                                   |                       |

//                                   v                       v

//                            ---------------   ---------------

//  double   ->               |s|exp| mant  |   |  mant       |

//                            ---------------   ---------------

//                            63     51   32   31              0

//

dest_dbl:

        clrl    %d0             //clear d0

        movew   LOCAL_EX(%a1),%d0       //get exponent

        subw    #0x3fff,%d0     //subtract extended precision bias

        cmpw    #0x4000,%d0     //check if inf

        beqs    inf             //if so, special case

        addw    #0x3ff,%d0      //add double precision bias

        swap    %d0             //d0 now in upper word

        lsll    #4,%d0          //d0 now in proper place for dbl prec exp

        tstb    LOCAL_SGN(%a1)

        beqs    get_mant        //if positive, go process mantissa

        bsetl   #31,%d0         //if negative, put in sign information

//                              ; before continuing

        bras    get_mant        //go process mantissa

inf:

        movel   #0x7ff00000,%d0 //load dbl inf exponent

        clrl    LOCAL_HI(%a1)   //clear msb

        tstb    LOCAL_SGN(%a1)

        beqs    dbl_inf         //if positive, go ahead and write it

        bsetl   #31,%d0         //if negative put in sign information

dbl_inf:

        movel   %d0,LOCAL_EX(%a1)       //put the new exp back on the stack

        bras    dbl_wrt

get_mant:

        movel   LOCAL_HI(%a1),%d1       //get ms mantissa

        bfextu  %d1{#1:#20},%d1 //get upper 20 bits of ms

        orl     %d1,%d0         //put these bits in ms word of double

        movel   %d0,LOCAL_EX(%a1)       //put the new exp back on the stack

        movel   LOCAL_HI(%a1),%d1       //get ms mantissa

        movel   #21,%d0         //load shift count

        lsll    %d0,%d1         //put lower 11 bits in upper bits

        movel   %d1,LOCAL_HI(%a1)       //build lower lword in memory

        movel   LOCAL_LO(%a1),%d1       //get ls mantissa

        bfextu  %d1{#0:#21},%d0 //get ls 21 bits of double

        orl     %d0,LOCAL_HI(%a1)       //put them in double result

dbl_wrt:

        movel   #0x8,%d0                //byte count for double precision number

        exg     %a0,%a1         //a0=supervisor source, a1=user dest

        bsrl    mem_write       //move the number to the user's memory

        rts

//

//      dest_sgl --- write single precision value to user space

//

//Input

//      a0 -> destination address

//      a1 -> source in extended precision

//

//Output

//      a0 -> destroyed

//      a1 -> destroyed

//      d0 -> 0

//

//Changes extended precision to single precision.

//      sgl_sign = ext_sign

//      sgl_exp = ext_exp - $3fff(ext bias) + $7f(sgl bias)

//      get rid of ext integer bit

//      sgl_mant = ext_mant{62:12}

//

//              ---------------   ---------------    ---------------

//  extended ->  |s|    exp    |   |1| ms mant   |    | ls mant     |

//              ---------------   ---------------    ---------------

//               95         64    63 62    40 32      31     12   0

//                                   |     |

//                                   |     |

//                                   |     |

//                                   v     v

//                            ---------------

//  single   ->               |s|exp| mant  |

//                            ---------------

//                            31     22     0

//

dest_sgl:

        clrl    %d0

        movew   LOCAL_EX(%a1),%d0       //get exponent

        subw    #0x3fff,%d0     //subtract extended precision bias

        cmpw    #0x4000,%d0     //check if inf

        beqs    sinf            //if so, special case

        addw    #0x7f,%d0               //add single precision bias

        swap    %d0             //put exp in upper word of d0

        lsll    #7,%d0          //shift it into single exp bits

        tstb    LOCAL_SGN(%a1)

        beqs    get_sman        //if positive, continue

        bsetl   #31,%d0         //if negative, put in sign first

        bras    get_sman        //get mantissa

sinf:

        movel   #0x7f800000,%d0 //load single inf exp to d0

        tstb    LOCAL_SGN(%a1)

        beqs    sgl_wrt         //if positive, continue

        bsetl   #31,%d0         //if negative, put in sign info

        bras    sgl_wrt

get_sman:

        movel   LOCAL_HI(%a1),%d1       //get ms mantissa

        bfextu  %d1{#1:#23},%d1 //get upper 23 bits of ms

        orl     %d1,%d0         //put these bits in ms word of single

sgl_wrt:

        movel   %d0,L_SCR1(%a6) //put the new exp back on the stack

        movel   #0x4,%d0                //byte count for single precision number

        tstl    %a0             //users destination address

        beqs    sgl_Dn          //destination is a data register

        exg     %a0,%a1         //a0=supervisor source, a1=user dest

        leal    L_SCR1(%a6),%a0 //point a0 to data

        bsrl    mem_write       //move the number to the user's memory

        rts

sgl_Dn:

        bsrl    get_fline       //returns fline word in d0

        andw    #0x7,%d0                //isolate register number

        movel   %d0,%d1         //d1 has size:reg formatted for reg_dest

        orl     #0x10,%d1               //reg_dest wants size added to reg#

        bral    reg_dest        //size is X, rts in reg_dest will

//                              ;return to caller of dest_sgl

dest_ext:

        tstb    LOCAL_SGN(%a1)  //put back sign into exponent word

        beqs    dstx_cont

        bsetb   #sign_bit,LOCAL_EX(%a1)

dstx_cont:

        clrb    LOCAL_SGN(%a1)  //clear out the sign byte

        movel   #0x0c,%d0               //byte count for extended number

        exg     %a0,%a1         //a0=supervisor source, a1=user dest

        bsrl    mem_write       //move the number to the user's memory

        rts

        |end