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[/] [or1k/] [trunk/] [uclinux/] [uClinux-2.0.x/] [arch/] [m68k/] [fpsp040/] [x_store.S] - Blame information for rev 1765

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Line No. Rev Author Line
1 199 simons
|
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|       x_store.sa 3.2 1/24/91
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|
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|       store --- store operand to memory or register
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|
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|       Used by underflow and overflow handlers.
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|
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|       a6 = points to fp value to be stored.
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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|       THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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_STORE:        |idnt    2,1 | Motorola 040 Floating Point Software Package
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        |section        8
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fpreg_mask:
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        .byte   0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01
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        .include "fpsp.h"
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        |xref   mem_write
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        |xref   get_fline
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        |xref   g_opcls
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        |xref   g_dfmtou
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        |xref   reg_dest
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        .global dest_ext
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        .global dest_dbl
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        .global dest_sgl
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        .global store
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store:
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        btstb   #E3,E_BYTE(%a6)
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        beqs    E1_sto
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E3_sto:
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        movel   CMDREG3B(%a6),%d0
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        bfextu  %d0{#6:#3},%d0          |isolate dest. reg from cmdreg3b
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sto_fp:
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        lea     fpreg_mask,%a1
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        moveb   (%a1,%d0.w),%d0         |convert reg# to dynamic register mask
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        tstb    LOCAL_SGN(%a0)
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        beqs    is_pos
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        bsetb   #sign_bit,LOCAL_EX(%a0)
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is_pos:
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        fmovemx (%a0),%d0               |move to correct register
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|
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|       if fp0-fp3 is being modified, we must put a copy
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|       in the USER_FPn variable on the stack because all exception
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|       handlers restore fp0-fp3 from there.
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|
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        cmpb    #0x80,%d0
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        bnes    not_fp0
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        fmovemx %fp0-%fp0,USER_FP0(%a6)
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        rts
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not_fp0:
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        cmpb    #0x40,%d0
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        bnes    not_fp1
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        fmovemx %fp1-%fp1,USER_FP1(%a6)
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        rts
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not_fp1:
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        cmpb    #0x20,%d0
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        bnes    not_fp2
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        fmovemx %fp2-%fp2,USER_FP2(%a6)
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        rts
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not_fp2:
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        cmpb    #0x10,%d0
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        bnes    not_fp3
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        fmovemx %fp3-%fp3,USER_FP3(%a6)
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        rts
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not_fp3:
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        rts
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E1_sto:
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        bsrl    g_opcls         |returns opclass in d0
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        cmpib   #3,%d0
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        beq     opc011          |branch if opclass 3
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        movel   CMDREG1B(%a6),%d0
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        bfextu  %d0{#6:#3},%d0  |extract destination register
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        bras    sto_fp
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opc011:
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        bsrl    g_dfmtou        |returns dest format in d0
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|                               ;ext=00, sgl=01, dbl=10
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        movel   %a0,%a1         |save source addr in a1
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        movel   EXC_EA(%a6),%a0 |get the address
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        cmpil   #0,%d0          |if dest format is extended
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        beq     dest_ext        |then branch
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        cmpil   #1,%d0          |if dest format is single
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        beqs    dest_sgl        |then branch
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|
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|       fall through to dest_dbl
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|
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|
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|       dest_dbl --- write double precision value to user space
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|
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|Input
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|       a0 -> destination address
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|       a1 -> source in extended precision
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|Output
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|       a0 -> destroyed
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|       a1 -> destroyed
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|       d0 -> 0
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|
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|Changes extended precision to double precision.
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| Note: no attempt is made to round the extended value to double.
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|       dbl_sign = ext_sign
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|       dbl_exp = ext_exp - $3fff(ext bias) + $7ff(dbl bias)
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|       get rid of ext integer bit
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|       dbl_mant = ext_mant{62:12}
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|
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|               ---------------   ---------------    ---------------
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|  extended ->  |s|    exp    |   |1| ms mant   |    | ls mant     |
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|               ---------------   ---------------    ---------------
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|                95         64    63 62       32      31     11   0
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|                                    |                       |
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|                                    |                       |
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|                                    |                       |
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|                                    v                       v
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|                             ---------------   ---------------
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|  double   ->                |s|exp| mant  |   |  mant       |
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|                             ---------------   ---------------
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|                             63     51   32   31              0
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|
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dest_dbl:
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        clrl    %d0             |clear d0
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        movew   LOCAL_EX(%a1),%d0       |get exponent
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        subw    #0x3fff,%d0     |subtract extended precision bias
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        cmpw    #0x4000,%d0     |check if inf
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        beqs    inf             |if so, special case
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        addw    #0x3ff,%d0      |add double precision bias
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        swap    %d0             |d0 now in upper word
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        lsll    #4,%d0          |d0 now in proper place for dbl prec exp
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        tstb    LOCAL_SGN(%a1)
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        beqs    get_mant        |if positive, go process mantissa
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        bsetl   #31,%d0         |if negative, put in sign information
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|                               ; before continuing
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        bras    get_mant        |go process mantissa
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inf:
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        movel   #0x7ff00000,%d0 |load dbl inf exponent
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        clrl    LOCAL_HI(%a1)   |clear msb
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        tstb    LOCAL_SGN(%a1)
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        beqs    dbl_inf         |if positive, go ahead and write it
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        bsetl   #31,%d0         |if negative put in sign information
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dbl_inf:
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        movel   %d0,LOCAL_EX(%a1)       |put the new exp back on the stack
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        bras    dbl_wrt
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get_mant:
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        movel   LOCAL_HI(%a1),%d1       |get ms mantissa
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        bfextu  %d1{#1:#20},%d1 |get upper 20 bits of ms
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        orl     %d1,%d0         |put these bits in ms word of double
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        movel   %d0,LOCAL_EX(%a1)       |put the new exp back on the stack
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        movel   LOCAL_HI(%a1),%d1       |get ms mantissa
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        movel   #21,%d0         |load shift count
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        lsll    %d0,%d1         |put lower 11 bits in upper bits
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        movel   %d1,LOCAL_HI(%a1)       |build lower lword in memory
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        movel   LOCAL_LO(%a1),%d1       |get ls mantissa
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        bfextu  %d1{#0:#21},%d0 |get ls 21 bits of double
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        orl     %d0,LOCAL_HI(%a1)       |put them in double result
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dbl_wrt:
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        movel   #0x8,%d0                |byte count for double precision number
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        exg     %a0,%a1         |a0=supervisor source, a1=user dest
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        bsrl    mem_write       |move the number to the user's memory
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        rts
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|
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|       dest_sgl --- write single precision value to user space
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|
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|Input
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|       a0 -> destination address
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|       a1 -> source in extended precision
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|
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|Output
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|       a0 -> destroyed
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|       a1 -> destroyed
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|       d0 -> 0
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|
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|Changes extended precision to single precision.
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|       sgl_sign = ext_sign
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|       sgl_exp = ext_exp - $3fff(ext bias) + $7f(sgl bias)
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|       get rid of ext integer bit
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|       sgl_mant = ext_mant{62:12}
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|
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|               ---------------   ---------------    ---------------
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|  extended ->  |s|    exp    |   |1| ms mant   |    | ls mant     |
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|               ---------------   ---------------    ---------------
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|                95         64    63 62    40 32      31     12   0
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|                                    |     |
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|                                    |     |
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|                                    |     |
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|                                    v     v
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|                             ---------------
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|  single   ->                |s|exp| mant  |
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|                             ---------------
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|                             31     22     0
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|
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dest_sgl:
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        clrl    %d0
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        movew   LOCAL_EX(%a1),%d0       |get exponent
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        subw    #0x3fff,%d0     |subtract extended precision bias
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        cmpw    #0x4000,%d0     |check if inf
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        beqs    sinf            |if so, special case
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        addw    #0x7f,%d0               |add single precision bias
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        swap    %d0             |put exp in upper word of d0
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        lsll    #7,%d0          |shift it into single exp bits
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        tstb    LOCAL_SGN(%a1)
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        beqs    get_sman        |if positive, continue
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        bsetl   #31,%d0         |if negative, put in sign first
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        bras    get_sman        |get mantissa
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sinf:
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        movel   #0x7f800000,%d0 |load single inf exp to d0
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        tstb    LOCAL_SGN(%a1)
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        beqs    sgl_wrt         |if positive, continue
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        bsetl   #31,%d0         |if negative, put in sign info
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        bras    sgl_wrt
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get_sman:
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        movel   LOCAL_HI(%a1),%d1       |get ms mantissa
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        bfextu  %d1{#1:#23},%d1 |get upper 23 bits of ms
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        orl     %d1,%d0         |put these bits in ms word of single
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sgl_wrt:
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        movel   %d0,L_SCR1(%a6) |put the new exp back on the stack
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        movel   #0x4,%d0                |byte count for single precision number
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        tstl    %a0             |users destination address
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        beqs    sgl_Dn          |destination is a data register
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        exg     %a0,%a1         |a0=supervisor source, a1=user dest
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        leal    L_SCR1(%a6),%a0 |point a0 to data
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        bsrl    mem_write       |move the number to the user's memory
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        rts
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sgl_Dn:
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        bsrl    get_fline       |returns fline word in d0
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        andw    #0x7,%d0                |isolate register number
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        movel   %d0,%d1         |d1 has size:reg formatted for reg_dest
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        orl     #0x10,%d1               |reg_dest wants size added to reg#
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        bral    reg_dest        |size is X, rts in reg_dest will
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|                               ;return to caller of dest_sgl
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dest_ext:
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        tstb    LOCAL_SGN(%a1)  |put back sign into exponent word
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        beqs    dstx_cont
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        bsetb   #sign_bit,LOCAL_EX(%a1)
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dstx_cont:
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        clrb    LOCAL_SGN(%a1)  |clear out the sign byte
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        movel   #0x0c,%d0               |byte count for extended number
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        exg     %a0,%a1         |a0=supervisor source, a1=user dest
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        bsrl    mem_write       |move the number to the user's memory
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        rts
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        |end

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