x_snan.sa revision 1.1
1 * MOTOROLA MICROPROCESSOR & MEMORY TECHNOLOGY GROUP 2 * M68000 Hi-Performance Microprocessor Division 3 * M68040 Software Package 4 * 5 * M68040 Software Package Copyright (c) 1993, 1994 Motorola Inc. 6 * All rights reserved. 7 * 8 * THE SOFTWARE is provided on an "AS IS" basis and without warranty. 9 * To the maximum extent permitted by applicable law, 10 * MOTOROLA DISCLAIMS ALL WARRANTIES WHETHER EXPRESS OR IMPLIED, 11 * INCLUDING IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A 12 * PARTICULAR PURPOSE and any warranty against infringement with 13 * regard to the SOFTWARE (INCLUDING ANY MODIFIED VERSIONS THEREOF) 14 * and any accompanying written materials. 15 * 16 * To the maximum extent permitted by applicable law, 17 * IN NO EVENT SHALL MOTOROLA BE LIABLE FOR ANY DAMAGES WHATSOEVER 18 * (INCLUDING WITHOUT LIMITATION, DAMAGES FOR LOSS OF BUSINESS 19 * PROFITS, BUSINESS INTERRUPTION, LOSS OF BUSINESS INFORMATION, OR 20 * OTHER PECUNIARY LOSS) ARISING OF THE USE OR INABILITY TO USE THE 21 * SOFTWARE. Motorola assumes no responsibility for the maintenance 22 * and support of the SOFTWARE. 23 * 24 * You are hereby granted a copyright license to use, modify, and 25 * distribute the SOFTWARE so long as this entire notice is retained 26 * without alteration in any modified and/or redistributed versions, 27 * and that such modified versions are clearly identified as such. 28 * No licenses are granted by implication, estoppel or otherwise 29 * under any patents or trademarks of Motorola, Inc. 30 31 * 32 * x_snan.sa 3.3 7/1/91 33 * 34 * fpsp_snan --- FPSP handler for signalling NAN exception 35 * 36 * SNAN for float -> integer conversions (integer conversion of 37 * an SNAN) is a non-maskable run-time exception. 38 * 39 * For trap disabled the 040 does the following: 40 * If the dest data format is s, d, or x, then the SNAN bit in the NAN 41 * is set to one and the resulting non-signaling NAN (truncated if 42 * necessary) is transferred to the dest. If the dest format is b, w, 43 * or l, then garbage is written to the dest (actually the upper 32 bits 44 * of the mantissa are sent to the integer unit). 45 * 46 * For trap enabled the 040 does the following: 47 * If the inst is move_out, then the results are the same as for trap 48 * disabled with the exception posted. If the instruction is not move_ 49 * out, the dest. is not modified, and the exception is posted. 50 * 51 52 X_SNAN IDNT 2,1 Motorola 040 Floating Point Software Package 53 54 section 8 55 56 include fpsp.h 57 58 xref get_fline 59 xref mem_write 60 xref real_snan 61 xref real_inex 62 xref fpsp_done 63 xref reg_dest 64 65 xdef fpsp_snan 66 fpsp_snan: 67 link a6,#-LOCAL_SIZE 68 fsave -(a7) 69 movem.l d0-d1/a0-a1,USER_DA(a6) 70 fmovem.x fp0-fp3,USER_FP0(a6) 71 fmovem.l fpcr/fpsr/fpiar,USER_FPCR(a6) 72 73 * 74 * Check if trap enabled 75 * 76 btst.b #snan_bit,FPCR_ENABLE(a6) 77 bne.b ena ;If enabled, then branch 78 79 bsr.l move_out ;else SNAN disabled 80 * 81 * It is possible to have an inex1 exception with the 82 * snan. If the inex enable bit is set in the FPCR, and either 83 * inex2 or inex1 occured, we must clean up and branch to the 84 * real inex handler. 85 * 86 ck_inex: 87 move.b FPCR_ENABLE(a6),d0 88 and.b FPSR_EXCEPT(a6),d0 89 andi.b #$3,d0 90 beq.w end_snan 91 * 92 * Inexact enabled and reported, and we must take an inexact exception. 93 * 94 take_inex: 95 move.b #INEX_VEC,EXC_VEC+1(a6) 96 movem.l USER_DA(a6),d0-d1/a0-a1 97 fmovem.x USER_FP0(a6),fp0-fp3 98 fmovem.l USER_FPCR(a6),fpcr/fpsr/fpiar 99 frestore (a7)+ 100 unlk a6 101 bra.l real_inex 102 * 103 * SNAN is enabled. Check if inst is move_out. 104 * Make any corrections to the 040 output as necessary. 105 * 106 ena: 107 btst.b #5,CMDREG1B(a6) ;if set, inst is move out 108 beq.w not_out 109 110 bsr.l move_out 111 112 report_snan: 113 move.b (a7),VER_TMP(a6) 114 cmpi.b #VER_40,(a7) ;test for orig unimp frame 115 bne.b ck_rev 116 moveq.l #13,d0 ;need to zero 14 lwords 117 bra.b rep_con 118 ck_rev: 119 moveq.l #11,d0 ;need to zero 12 lwords 120 rep_con: 121 clr.l (a7) 122 loop1: 123 clr.l -(a7) ;clear and dec a7 124 dbra.w d0,loop1 125 move.b VER_TMP(a6),(a7) ;format a busy frame 126 move.b #BUSY_SIZE-4,1(a7) 127 move.l USER_FPSR(a6),FPSR_SHADOW(a6) 128 or.l #sx_mask,E_BYTE(a6) 129 movem.l USER_DA(a6),d0-d1/a0-a1 130 fmovem.x USER_FP0(a6),fp0-fp3 131 fmovem.l USER_FPCR(a6),fpcr/fpsr/fpiar 132 frestore (a7)+ 133 unlk a6 134 bra.l real_snan 135 * 136 * Exit snan handler by expanding the unimp frame into a busy frame 137 * 138 end_snan: 139 bclr.b #E1,E_BYTE(a6) 140 141 move.b (a7),VER_TMP(a6) 142 cmpi.b #VER_40,(a7) ;test for orig unimp frame 143 bne.b ck_rev2 144 moveq.l #13,d0 ;need to zero 14 lwords 145 bra.b rep_con2 146 ck_rev2: 147 moveq.l #11,d0 ;need to zero 12 lwords 148 rep_con2: 149 clr.l (a7) 150 loop2: 151 clr.l -(a7) ;clear and dec a7 152 dbra.w d0,loop2 153 move.b VER_TMP(a6),(a7) ;format a busy frame 154 move.b #BUSY_SIZE-4,1(a7) ;write busy size 155 move.l USER_FPSR(a6),FPSR_SHADOW(a6) 156 or.l #sx_mask,E_BYTE(a6) 157 movem.l USER_DA(a6),d0-d1/a0-a1 158 fmovem.x USER_FP0(a6),fp0-fp3 159 fmovem.l USER_FPCR(a6),fpcr/fpsr/fpiar 160 frestore (a7)+ 161 unlk a6 162 bra.l fpsp_done 163 164 * 165 * Move_out 166 * 167 move_out: 168 move.l EXC_EA(a6),a0 ;get <ea> from exc frame 169 170 bfextu CMDREG1B(a6){3:3},d0 ;move rx field to d0{2:0} 171 cmpi.l #0,d0 ;check for long 172 beq.b sto_long ;branch if move_out long 173 174 cmpi.l #4,d0 ;check for word 175 beq.b sto_word ;branch if move_out word 176 177 cmpi.l #6,d0 ;check for byte 178 beq.b sto_byte ;branch if move_out byte 179 180 * 181 * Not byte, word or long 182 * 183 rts 184 * 185 * Get the 32 most significant bits of etemp mantissa 186 * 187 sto_long: 188 move.l ETEMP_HI(a6),d1 189 move.l #4,d0 ;load byte count 190 * 191 * Set signalling nan bit 192 * 193 bset.l #30,d1 194 * 195 * Store to the users destination address 196 * 197 tst.l a0 ;check if <ea> is 0 198 beq.b wrt_dn ;destination is a data register 199 200 move.l d1,-(a7) ;move the snan onto the stack 201 move.l a0,a1 ;load dest addr into a1 202 move.l a7,a0 ;load src addr of snan into a0 203 bsr.l mem_write ;write snan to user memory 204 move.l (a7)+,d1 ;clear off stack 205 rts 206 * 207 * Get the 16 most significant bits of etemp mantissa 208 * 209 sto_word: 210 move.l ETEMP_HI(a6),d1 211 move.l #2,d0 ;load byte count 212 * 213 * Set signalling nan bit 214 * 215 bset.l #30,d1 216 * 217 * Store to the users destination address 218 * 219 tst.l a0 ;check if <ea> is 0 220 beq.b wrt_dn ;destination is a data register 221 222 move.l d1,-(a7) ;move the snan onto the stack 223 move.l a0,a1 ;load dest addr into a1 224 move.l a7,a0 ;point to low word 225 bsr.l mem_write ;write snan to user memory 226 move.l (a7)+,d1 ;clear off stack 227 rts 228 * 229 * Get the 8 most significant bits of etemp mantissa 230 * 231 sto_byte: 232 move.l ETEMP_HI(a6),d1 233 move.l #1,d0 ;load byte count 234 * 235 * Set signalling nan bit 236 * 237 bset.l #30,d1 238 * 239 * Store to the users destination address 240 * 241 tst.l a0 ;check if <ea> is 0 242 beq.b wrt_dn ;destination is a data register 243 move.l d1,-(a7) ;move the snan onto the stack 244 move.l a0,a1 ;load dest addr into a1 245 move.l a7,a0 ;point to source byte 246 bsr.l mem_write ;write snan to user memory 247 move.l (a7)+,d1 ;clear off stack 248 rts 249 250 * 251 * wrt_dn --- write to a data register 252 * 253 * We get here with D1 containing the data to write and D0 the 254 * number of bytes to write: 1=byte,2=word,4=long. 255 * 256 wrt_dn: 257 move.l d1,L_SCR1(a6) ;data 258 move.l d0,-(a7) ;size 259 bsr.l get_fline ;returns fline word in d0 260 move.l d0,d1 261 andi.l #$7,d1 ;d1 now holds register number 262 move.l (sp)+,d0 ;get original size 263 cmpi.l #4,d0 264 beq.b wrt_long 265 cmpi.l #2,d0 266 bne.b wrt_byte 267 wrt_word: 268 or.l #$8,d1 269 bra.l reg_dest 270 wrt_long: 271 or.l #$10,d1 272 bra.l reg_dest 273 wrt_byte: 274 bra.l reg_dest 275 * 276 * Check if it is a src nan or dst nan 277 * 278 not_out: 279 move.l DTAG(a6),d0 280 bfextu d0{0:3},d0 ;isolate dtag in lsbs 281 282 cmpi.b #3,d0 ;check for nan in destination 283 bne.b issrc ;destination nan has priority 284 dst_nan: 285 btst.b #6,FPTEMP_HI(a6) ;check if dest nan is an snan 286 bne.b issrc ;no, so check source for snan 287 move.w FPTEMP_EX(a6),d0 288 bra.b cont 289 issrc: 290 move.w ETEMP_EX(a6),d0 291 cont: 292 btst.l #15,d0 ;test for sign of snan 293 beq.b clr_neg 294 bset.b #neg_bit,FPSR_CC(a6) 295 bra.w report_snan 296 clr_neg: 297 bclr.b #neg_bit,FPSR_CC(a6) 298 bra.w report_snan 299 300 end 301
Indexes created Tue Oct 14 21:09:58 GMT 2025