arch/m68k/fpsp040/x_store.S

   1 |
   2 |       x_store.sa 3.2 1/24/91
   3 |
   4 |       store --- store operand to memory or register
   5 |
   6 |       Used by underflow and overflow handlers.
   7 |
   8 |       a6 = points to fp value to be stored.
   9 |
  10
  11 |               Copyright (C) Motorola, Inc. 1990
  12 |                       All Rights Reserved
  13 |
  14 |       For details on the license for this file, please see the
  15 |       file, README, in this same directory.
  16
  17 X_STORE:        |idnt    2,1 | Motorola 040 Floating Point Software Package
  18
  19         |section        8
  20
  21 fpreg_mask:
  22         .byte   0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01
  23
  24 #include "fpsp.h"
  25
  26         |xref   mem_write
  27         |xref   get_fline
  28         |xref   g_opcls
  29         |xref   g_dfmtou
  30         |xref   reg_dest
  31
  32         .global dest_ext
  33         .global dest_dbl
  34         .global dest_sgl
  35
  36         .global store
  37 store:
  38         btstb   #E3,E_BYTE(%a6)
  39         beqs    E1_sto
  40 E3_sto:
  41         movel   CMDREG3B(%a6),%d0
  42         bfextu  %d0{#6:#3},%d0          |isolate dest. reg from cmdreg3b
  43 sto_fp:
  44         lea     fpreg_mask,%a1
  45         moveb   (%a1,%d0.w),%d0         |convert reg# to dynamic register mask
  46         tstb    LOCAL_SGN(%a0)
  47         beqs    is_pos
  48         bsetb   #sign_bit,LOCAL_EX(%a0)
  49 is_pos:
  50         fmovemx (%a0),%d0               |move to correct register
  51 |
  52 |       if fp0-fp3 is being modified, we must put a copy
  53 |       in the USER_FPn variable on the stack because all exception
  54 |       handlers restore fp0-fp3 from there.
  55 |
  56         cmpb    #0x80,%d0
  57         bnes    not_fp0
  58         fmovemx %fp0-%fp0,USER_FP0(%a6)
  59         rts
  60 not_fp0:
  61         cmpb    #0x40,%d0
  62         bnes    not_fp1
  63         fmovemx %fp1-%fp1,USER_FP1(%a6)
  64         rts
  65 not_fp1:
  66         cmpb    #0x20,%d0
  67         bnes    not_fp2
  68         fmovemx %fp2-%fp2,USER_FP2(%a6)
  69         rts
  70 not_fp2:
  71         cmpb    #0x10,%d0
  72         bnes    not_fp3
  73         fmovemx %fp3-%fp3,USER_FP3(%a6)
  74         rts
  75 not_fp3:
  76         rts
  77
  78 E1_sto:
  79         bsrl    g_opcls         |returns opclass in d0
  80         cmpib   #3,%d0
  81         beq     opc011          |branch if opclass 3
  82         movel   CMDREG1B(%a6),%d0
  83         bfextu  %d0{#6:#3},%d0  |extract destination register
  84         bras    sto_fp
  85
  86 opc011:
  87         bsrl    g_dfmtou        |returns dest format in d0
  88 |                               ;ext=00, sgl=01, dbl=10
  89         movel   %a0,%a1         |save source addr in a1
  90         movel   EXC_EA(%a6),%a0 |get the address
  91         cmpil   #0,%d0          |if dest format is extended
  92         beq     dest_ext        |then branch
  93         cmpil   #1,%d0          |if dest format is single
  94         beq     dest_sgl        |then branch
  95 |
  96 |       fall through to dest_dbl
  97 |
  98
  99 |
 100 |       dest_dbl --- write double precision value to user space
 101 |
 102 |Input
 103 |       a0 -> destination address
 104 |       a1 -> source in extended precision
 105 |Output
 106 |       a0 -> destroyed
 107 |       a1 -> destroyed
 108 |       d0 -> 0
 109 |
 110 |Changes extended precision to double precision.
 111 | Note: no attempt is made to round the extended value to double.
 112 |       dbl_sign = ext_sign
 113 |       dbl_exp = ext_exp - $3fff(ext bias) + $7ff(dbl bias)
 114 |       get rid of ext integer bit
 115 |       dbl_mant = ext_mant{62:12}
 116 |
 117 |               ---------------   ---------------    ---------------
 118 |  extended ->  |s|    exp    |   |1| ms mant   |    | ls mant     |
 119 |               ---------------   ---------------    ---------------
 120 |                95         64    63 62       32      31     11   0
 121 |                                    |                       |
 122 |                                    |                       |
 123 |                                    |                       |
 124 |                                    v                       v
 125 |                             ---------------   ---------------
 126 |  double   ->                |s|exp| mant  |   |  mant       |
 127 |                             ---------------   ---------------
 128 |                             63     51   32   31              0
 129 |
 130 dest_dbl:
 131         clrl    %d0             |clear d0
 132         movew   LOCAL_EX(%a1),%d0       |get exponent
 133         subw    #0x3fff,%d0     |subtract extended precision bias
 134         cmpw    #0x4000,%d0     |check if inf
 135         beqs    inf             |if so, special case
 136         addw    #0x3ff,%d0      |add double precision bias
 137         swap    %d0             |d0 now in upper word
 138         lsll    #4,%d0          |d0 now in proper place for dbl prec exp
 139         tstb    LOCAL_SGN(%a1)
 140         beqs    get_mant        |if positive, go process mantissa
 141         bsetl   #31,%d0         |if negative, put in sign information
 142 |                               ; before continuing
 143         bras    get_mant        |go process mantissa
 144 inf:
 145         movel   #0x7ff00000,%d0 |load dbl inf exponent
 146         clrl    LOCAL_HI(%a1)   |clear msb
 147         tstb    LOCAL_SGN(%a1)
 148         beqs    dbl_inf         |if positive, go ahead and write it
 149         bsetl   #31,%d0         |if negative put in sign information
 150 dbl_inf:
 151         movel   %d0,LOCAL_EX(%a1)       |put the new exp back on the stack
 152         bras    dbl_wrt
 153 get_mant:
 154         movel   LOCAL_HI(%a1),%d1       |get ms mantissa
 155         bfextu  %d1{#1:#20},%d1 |get upper 20 bits of ms
 156         orl     %d1,%d0         |put these bits in ms word of double
 157         movel   %d0,LOCAL_EX(%a1)       |put the new exp back on the stack
 158         movel   LOCAL_HI(%a1),%d1       |get ms mantissa
 159         movel   #21,%d0         |load shift count
 160         lsll    %d0,%d1         |put lower 11 bits in upper bits
 161         movel   %d1,LOCAL_HI(%a1)       |build lower lword in memory
 162         movel   LOCAL_LO(%a1),%d1       |get ls mantissa
 163         bfextu  %d1{#0:#21},%d0 |get ls 21 bits of double
 164         orl     %d0,LOCAL_HI(%a1)       |put them in double result
 165 dbl_wrt:
 166         movel   #0x8,%d0                |byte count for double precision number
 167         exg     %a0,%a1         |a0=supervisor source, a1=user dest
 168         bsrl    mem_write       |move the number to the user's memory
 169         rts
 170 |
 171 |       dest_sgl --- write single precision value to user space
 172 |
 173 |Input
 174 |       a0 -> destination address
 175 |       a1 -> source in extended precision
 176 |
 177 |Output
 178 |       a0 -> destroyed
 179 |       a1 -> destroyed
 180 |       d0 -> 0
 181 |
 182 |Changes extended precision to single precision.
 183 |       sgl_sign = ext_sign
 184 |       sgl_exp = ext_exp - $3fff(ext bias) + $7f(sgl bias)
 185 |       get rid of ext integer bit
 186 |       sgl_mant = ext_mant{62:12}
 187 |
 188 |               ---------------   ---------------    ---------------
 189 |  extended ->  |s|    exp    |   |1| ms mant   |    | ls mant     |
 190 |               ---------------   ---------------    ---------------
 191 |                95         64    63 62    40 32      31     12   0
 192 |                                    |     |
 193 |                                    |     |
 194 |                                    |     |
 195 |                                    v     v
 196 |                             ---------------
 197 |  single   ->                |s|exp| mant  |
 198 |                             ---------------
 199 |                             31     22     0
 200 |
 201 dest_sgl:
 202         clrl    %d0
 203         movew   LOCAL_EX(%a1),%d0       |get exponent
 204         subw    #0x3fff,%d0     |subtract extended precision bias
 205         cmpw    #0x4000,%d0     |check if inf
 206         beqs    sinf            |if so, special case
 207         addw    #0x7f,%d0               |add single precision bias
 208         swap    %d0             |put exp in upper word of d0
 209         lsll    #7,%d0          |shift it into single exp bits
 210         tstb    LOCAL_SGN(%a1)
 211         beqs    get_sman        |if positive, continue
 212         bsetl   #31,%d0         |if negative, put in sign first
 213         bras    get_sman        |get mantissa
 214 sinf:
 215         movel   #0x7f800000,%d0 |load single inf exp to d0
 216         tstb    LOCAL_SGN(%a1)
 217         beqs    sgl_wrt         |if positive, continue
 218         bsetl   #31,%d0         |if negative, put in sign info
 219         bras    sgl_wrt
 220
 221 get_sman:
 222         movel   LOCAL_HI(%a1),%d1       |get ms mantissa
 223         bfextu  %d1{#1:#23},%d1 |get upper 23 bits of ms
 224         orl     %d1,%d0         |put these bits in ms word of single
 225
 226 sgl_wrt:
 227         movel   %d0,L_SCR1(%a6) |put the new exp back on the stack
 228         movel   #0x4,%d0                |byte count for single precision number
 229         tstl    %a0             |users destination address
 230         beqs    sgl_Dn          |destination is a data register
 231         exg     %a0,%a1         |a0=supervisor source, a1=user dest
 232         leal    L_SCR1(%a6),%a0 |point a0 to data
 233         bsrl    mem_write       |move the number to the user's memory
 234         rts
 235 sgl_Dn:
 236         bsrl    get_fline       |returns fline word in d0
 237         andw    #0x7,%d0                |isolate register number
 238         movel   %d0,%d1         |d1 has size:reg formatted for reg_dest
 239         orl     #0x10,%d1               |reg_dest wants size added to reg#
 240         bral    reg_dest        |size is X, rts in reg_dest will
 241 |                               ;return to caller of dest_sgl
 242
 243 dest_ext:
 244         tstb    LOCAL_SGN(%a1)  |put back sign into exponent word
 245         beqs    dstx_cont
 246         bsetb   #sign_bit,LOCAL_EX(%a1)
 247 dstx_cont:
 248         clrb    LOCAL_SGN(%a1)  |clear out the sign byte
 249
 250         movel   #0x0c,%d0               |byte count for extended number
 251         exg     %a0,%a1         |a0=supervisor source, a1=user dest
 252         bsrl    mem_write       |move the number to the user's memory
 253         rts
 254
 255         |end