arch/m68k/fpsp040/x_snan.S

   1 |
   2 |       x_snan.sa 3.3 7/1/91
   3 |
   4 | fpsp_snan --- FPSP handler for signalling NAN exception
   5 |
   6 | SNAN for float -> integer conversions (integer conversion of
   7 | an SNAN) is a non-maskable run-time exception.
   8 |
   9 | For trap disabled the 040 does the following:
  10 | If the dest data format is s, d, or x, then the SNAN bit in the NAN
  11 | is set to one and the resulting non-signaling NAN (truncated if
  12 | necessary) is transferred to the dest.  If the dest format is b, w,
  13 | or l, then garbage is written to the dest (actually the upper 32 bits
  14 | of the mantissa are sent to the integer unit).
  15 |
  16 | For trap enabled the 040 does the following:
  17 | If the inst is move_out, then the results are the same as for trap
  18 | disabled with the exception posted.  If the instruction is not move_
  19 | out, the dest. is not modified, and the exception is posted.
  20 |
  21
  22 |               Copyright (C) Motorola, Inc. 1990
  23 |                       All Rights Reserved
  24 |
  25 |       THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
  26 |       The copyright notice above does not evidence any
  27 |       actual or intended publication of such source code.
  28
  29 X_SNAN: |idnt    2,1 | Motorola 040 Floating Point Software Package
  30
  31         |section        8
  32
  33 #include "fpsp.h"
  34
  35         |xref   get_fline
  36         |xref   mem_write
  37         |xref   real_snan
  38         |xref   real_inex
  39         |xref   fpsp_done
  40         |xref   reg_dest
  41
  42         .global fpsp_snan
  43 fpsp_snan:
  44         link            %a6,#-LOCAL_SIZE
  45         fsave           -(%a7)
  46         moveml          %d0-%d1/%a0-%a1,USER_DA(%a6)
  47         fmovemx %fp0-%fp3,USER_FP0(%a6)
  48         fmoveml %fpcr/%fpsr/%fpiar,USER_FPCR(%a6)
  49
  50 |
  51 | Check if trap enabled
  52 |
  53         btstb           #snan_bit,FPCR_ENABLE(%a6)
  54         bnes            ena             |If enabled, then branch
  55
  56         bsrl            move_out        |else SNAN disabled
  57 |
  58 | It is possible to have an inex1 exception with the
  59 | snan.  If the inex enable bit is set in the FPCR, and either
  60 | inex2 or inex1 occurred, we must clean up and branch to the
  61 | real inex handler.
  62 |
  63 ck_inex:
  64         moveb   FPCR_ENABLE(%a6),%d0
  65         andb    FPSR_EXCEPT(%a6),%d0
  66         andib   #0x3,%d0
  67         beq     end_snan
  68 |
  69 | Inexact enabled and reported, and we must take an inexact exception.
  70 |
  71 take_inex:
  72         moveb           #INEX_VEC,EXC_VEC+1(%a6)
  73         moveml          USER_DA(%a6),%d0-%d1/%a0-%a1
  74         fmovemx USER_FP0(%a6),%fp0-%fp3
  75         fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
  76         frestore        (%a7)+
  77         unlk            %a6
  78         bral            real_inex
  79 |
  80 | SNAN is enabled.  Check if inst is move_out.
  81 | Make any corrections to the 040 output as necessary.
  82 |
  83 ena:
  84         btstb           #5,CMDREG1B(%a6) |if set, inst is move out
  85         beq             not_out
  86
  87         bsrl            move_out
  88
  89 report_snan:
  90         moveb           (%a7),VER_TMP(%a6)
  91         cmpib           #VER_40,(%a7)   |test for orig unimp frame
  92         bnes            ck_rev
  93         moveql          #13,%d0         |need to zero 14 lwords
  94         bras            rep_con
  95 ck_rev:
  96         moveql          #11,%d0         |need to zero 12 lwords
  97 rep_con:
  98         clrl            (%a7)
  99 loop1:
 100         clrl            -(%a7)          |clear and dec a7
 101         dbra            %d0,loop1
 102         moveb           VER_TMP(%a6),(%a7) |format a busy frame
 103         moveb           #BUSY_SIZE-4,1(%a7)
 104         movel           USER_FPSR(%a6),FPSR_SHADOW(%a6)
 105         orl             #sx_mask,E_BYTE(%a6)
 106         moveml          USER_DA(%a6),%d0-%d1/%a0-%a1
 107         fmovemx USER_FP0(%a6),%fp0-%fp3
 108         fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
 109         frestore        (%a7)+
 110         unlk            %a6
 111         bral            real_snan
 112 |
 113 | Exit snan handler by expanding the unimp frame into a busy frame
 114 |
 115 end_snan:
 116         bclrb           #E1,E_BYTE(%a6)
 117
 118         moveb           (%a7),VER_TMP(%a6)
 119         cmpib           #VER_40,(%a7)   |test for orig unimp frame
 120         bnes            ck_rev2
 121         moveql          #13,%d0         |need to zero 14 lwords
 122         bras            rep_con2
 123 ck_rev2:
 124         moveql          #11,%d0         |need to zero 12 lwords
 125 rep_con2:
 126         clrl            (%a7)
 127 loop2:
 128         clrl            -(%a7)          |clear and dec a7
 129         dbra            %d0,loop2
 130         moveb           VER_TMP(%a6),(%a7) |format a busy frame
 131         moveb           #BUSY_SIZE-4,1(%a7) |write busy size
 132         movel           USER_FPSR(%a6),FPSR_SHADOW(%a6)
 133         orl             #sx_mask,E_BYTE(%a6)
 134         moveml          USER_DA(%a6),%d0-%d1/%a0-%a1
 135         fmovemx USER_FP0(%a6),%fp0-%fp3
 136         fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
 137         frestore        (%a7)+
 138         unlk            %a6
 139         bral            fpsp_done
 140
 141 |
 142 | Move_out
 143 |
 144 move_out:
 145         movel           EXC_EA(%a6),%a0 |get <ea> from exc frame
 146
 147         bfextu          CMDREG1B(%a6){#3:#3},%d0 |move rx field to d0{2:0}
 148         cmpil           #0,%d0          |check for long
 149         beqs            sto_long        |branch if move_out long
 150
 151         cmpil           #4,%d0          |check for word
 152         beqs            sto_word        |branch if move_out word
 153
 154         cmpil           #6,%d0          |check for byte
 155         beqs            sto_byte        |branch if move_out byte
 156
 157 |
 158 | Not byte, word or long
 159 |
 160         rts
 161 |
 162 | Get the 32 most significant bits of etemp mantissa
 163 |
 164 sto_long:
 165         movel           ETEMP_HI(%a6),%d1
 166         movel           #4,%d0          |load byte count
 167 |
 168 | Set signalling nan bit
 169 |
 170         bsetl           #30,%d1
 171 |
 172 | Store to the users destination address
 173 |
 174         tstl            %a0             |check if <ea> is 0
 175         beqs            wrt_dn          |destination is a data register
 176
 177         movel           %d1,-(%a7)      |move the snan onto the stack
 178         movel           %a0,%a1         |load dest addr into a1
 179         movel           %a7,%a0         |load src addr of snan into a0
 180         bsrl            mem_write       |write snan to user memory
 181         movel           (%a7)+,%d1      |clear off stack
 182         rts
 183 |
 184 | Get the 16 most significant bits of etemp mantissa
 185 |
 186 sto_word:
 187         movel           ETEMP_HI(%a6),%d1
 188         movel           #2,%d0          |load byte count
 189 |
 190 | Set signalling nan bit
 191 |
 192         bsetl           #30,%d1
 193 |
 194 | Store to the users destination address
 195 |
 196         tstl            %a0             |check if <ea> is 0
 197         beqs            wrt_dn          |destination is a data register
 198
 199         movel           %d1,-(%a7)      |move the snan onto the stack
 200         movel           %a0,%a1         |load dest addr into a1
 201         movel           %a7,%a0         |point to low word
 202         bsrl            mem_write       |write snan to user memory
 203         movel           (%a7)+,%d1      |clear off stack
 204         rts
 205 |
 206 | Get the 8 most significant bits of etemp mantissa
 207 |
 208 sto_byte:
 209         movel           ETEMP_HI(%a6),%d1
 210         movel           #1,%d0          |load byte count
 211 |
 212 | Set signalling nan bit
 213 |
 214         bsetl           #30,%d1
 215 |
 216 | Store to the users destination address
 217 |
 218         tstl            %a0             |check if <ea> is 0
 219         beqs            wrt_dn          |destination is a data register
 220         movel           %d1,-(%a7)      |move the snan onto the stack
 221         movel           %a0,%a1         |load dest addr into a1
 222         movel           %a7,%a0         |point to source byte
 223         bsrl            mem_write       |write snan to user memory
 224         movel           (%a7)+,%d1      |clear off stack
 225         rts
 226
 227 |
 228 |       wrt_dn --- write to a data register
 229 |
 230 |       We get here with D1 containing the data to write and D0 the
 231 |       number of bytes to write: 1=byte,2=word,4=long.
 232 |
 233 wrt_dn:
 234         movel           %d1,L_SCR1(%a6) |data
 235         movel           %d0,-(%a7)      |size
 236         bsrl            get_fline       |returns fline word in d0
 237         movel           %d0,%d1
 238         andil           #0x7,%d1                |d1 now holds register number
 239         movel           (%sp)+,%d0      |get original size
 240         cmpil           #4,%d0
 241         beqs            wrt_long
 242         cmpil           #2,%d0
 243         bnes            wrt_byte
 244 wrt_word:
 245         orl             #0x8,%d1
 246         bral            reg_dest
 247 wrt_long:
 248         orl             #0x10,%d1
 249         bral            reg_dest
 250 wrt_byte:
 251         bral            reg_dest
 252 |
 253 | Check if it is a src nan or dst nan
 254 |
 255 not_out:
 256         movel           DTAG(%a6),%d0
 257         bfextu          %d0{#0:#3},%d0  |isolate dtag in lsbs
 258
 259         cmpib           #3,%d0          |check for nan in destination
 260         bnes            issrc           |destination nan has priority
 261 dst_nan:
 262         btstb           #6,FPTEMP_HI(%a6) |check if dest nan is an snan
 263         bnes            issrc           |no, so check source for snan
 264         movew           FPTEMP_EX(%a6),%d0
 265         bras            cont
 266 issrc:
 267         movew           ETEMP_EX(%a6),%d0
 268 cont:
 269         btstl           #15,%d0         |test for sign of snan
 270         beqs            clr_neg
 271         bsetb           #neg_bit,FPSR_CC(%a6)
 272         bra             report_snan
 273 clr_neg:
 274         bclrb           #neg_bit,FPSR_CC(%a6)
 275         bra             report_snan
 276
 277         |end