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