x_ovfl.sa revision 1.4
1 * $NetBSD: x_ovfl.sa,v 1.4 2024/09/20 19:38:53 andvar Exp $ 2 3 * MOTOROLA MICROPROCESSOR & MEMORY TECHNOLOGY GROUP 4 * M68000 Hi-Performance Microprocessor Division 5 * M68040 Software Package 6 * 7 * M68040 Software Package Copyright (c) 1993, 1994 Motorola Inc. 8 * All rights reserved. 9 * 10 * THE SOFTWARE is provided on an "AS IS" basis and without warranty. 11 * To the maximum extent permitted by applicable law, 12 * MOTOROLA DISCLAIMS ALL WARRANTIES WHETHER EXPRESS OR IMPLIED, 13 * INCLUDING IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A 14 * PARTICULAR PURPOSE and any warranty against infringement with 15 * regard to the SOFTWARE (INCLUDING ANY MODIFIED VERSIONS THEREOF) 16 * and any accompanying written materials. 17 * 18 * To the maximum extent permitted by applicable law, 19 * IN NO EVENT SHALL MOTOROLA BE LIABLE FOR ANY DAMAGES WHATSOEVER 20 * (INCLUDING WITHOUT LIMITATION, DAMAGES FOR LOSS OF BUSINESS 21 * PROFITS, BUSINESS INTERRUPTION, LOSS OF BUSINESS INFORMATION, OR 22 * OTHER PECUNIARY LOSS) ARISING OF THE USE OR INABILITY TO USE THE 23 * SOFTWARE. Motorola assumes no responsibility for the maintenance 24 * and support of the SOFTWARE. 25 * 26 * You are hereby granted a copyright license to use, modify, and 27 * distribute the SOFTWARE so long as this entire notice is retained 28 * without alteration in any modified and/or redistributed versions, 29 * and that such modified versions are clearly identified as such. 30 * No licenses are granted by implication, estoppel or otherwise 31 * under any patents or trademarks of Motorola, Inc. 32 33 * 34 * x_ovfl.sa 3.5 7/1/91 35 * 36 * fpsp_ovfl --- FPSP handler for overflow exception 37 * 38 * Overflow occurs when a floating-point intermediate result is 39 * too large to be represented in a floating-point data register, 40 * or when storing to memory, the contents of a floating-point 41 * data register are too large to be represented in the 42 * destination format. 43 * 44 * Trap disabled results 45 * 46 * If the instruction is move_out, then garbage is stored in the 47 * destination. If the instruction is not move_out, then the 48 * destination is not affected. For 68881 compatibility, the 49 * following values should be stored at the destination, based 50 * on the current rounding mode: 51 * 52 * RN Infinity with the sign of the intermediate result. 53 * RZ Largest magnitude number, with the sign of the 54 * intermediate result. 55 * RM For pos overflow, the largest pos number. For neg overflow, 56 * -infinity 57 * RP For pos overflow, +infinity. For neg overflow, the largest 58 * neg number 59 * 60 * Trap enabled results 61 * All trap disabled code applies. In addition the exceptional 62 * operand needs to be made available to the users exception handler 63 * with a bias of $6000 subtracted from the exponent. 64 * 65 66 X_OVFL IDNT 2,1 Motorola 040 Floating Point Software Package 67 68 section 8 69 70 include fpsp.h 71 72 xref ovf_r_x2 73 xref ovf_r_x3 74 xref store 75 xref real_ovfl 76 xref real_inex 77 xref fpsp_done 78 xref g_opcls 79 xref b1238_fix 80 81 xdef fpsp_ovfl 82 fpsp_ovfl: 83 link a6,#-LOCAL_SIZE 84 fsave -(a7) 85 movem.l d0-d1/a0-a1,USER_DA(a6) 86 fmovem.x fp0-fp3,USER_FP0(a6) 87 fmovem.l fpcr/fpsr/fpiar,USER_FPCR(a6) 88 89 * 90 * The 040 doesn't set the AINEX bit in the FPSR, the following 91 * line temporarily rectifies this error. 92 * 93 bset.b #ainex_bit,FPSR_AEXCEPT(a6) 94 * 95 bsr.l ovf_adj ;denormalize, round & store interm op 96 * 97 * if overflow traps not enabled check for inexact exception 98 * 99 btst.b #ovfl_bit,FPCR_ENABLE(a6) 100 beq.b ck_inex 101 * 102 btst.b #E3,E_BYTE(a6) 103 beq.b no_e3_1 104 bfextu CMDREG3B(a6){6:3},d0 ;get dest reg no 105 bclr.b d0,FPR_DIRTY_BITS(a6) ;clr dest dirty bit 106 bsr.l b1238_fix 107 move.l USER_FPSR(a6),FPSR_SHADOW(a6) 108 or.l #sx_mask,E_BYTE(a6) 109 no_e3_1: 110 movem.l USER_DA(a6),d0-d1/a0-a1 111 fmovem.x USER_FP0(a6),fp0-fp3 112 fmovem.l USER_FPCR(a6),fpcr/fpsr/fpiar 113 frestore (a7)+ 114 unlk a6 115 bra.l real_ovfl 116 * 117 * It is possible to have either inex2 or inex1 exceptions with the 118 * ovfl. If the inex enable bit is set in the FPCR, and either 119 * inex2 or inex1 occurred, we must clean up and branch to the 120 * real inex handler. 121 * 122 ck_inex: 123 * move.b FPCR_ENABLE(a6),d0 124 * and.b FPSR_EXCEPT(a6),d0 125 * andi.b #$3,d0 126 btst.b #inex2_bit,FPCR_ENABLE(a6) 127 beq.b ovfl_exit 128 * 129 * Inexact enabled and reported, and we must take an inexact exception. 130 * 131 take_inex: 132 btst.b #E3,E_BYTE(a6) 133 beq.b no_e3_2 134 bfextu CMDREG3B(a6){6:3},d0 ;get dest reg no 135 bclr.b d0,FPR_DIRTY_BITS(a6) ;clr dest dirty bit 136 bsr.l b1238_fix 137 move.l USER_FPSR(a6),FPSR_SHADOW(a6) 138 or.l #sx_mask,E_BYTE(a6) 139 no_e3_2: 140 move.b #INEX_VEC,EXC_VEC+1(a6) 141 movem.l USER_DA(a6),d0-d1/a0-a1 142 fmovem.x USER_FP0(a6),fp0-fp3 143 fmovem.l USER_FPCR(a6),fpcr/fpsr/fpiar 144 frestore (a7)+ 145 unlk a6 146 bra.l real_inex 147 148 ovfl_exit: 149 bclr.b #E3,E_BYTE(a6) ;test and clear E3 bit 150 beq.b e1_set 151 * 152 * Clear dirty bit on dest register in the frame before branching 153 * to b1238_fix. 154 * 155 bfextu CMDREG3B(a6){6:3},d0 ;get dest reg no 156 bclr.b d0,FPR_DIRTY_BITS(a6) ;clr dest dirty bit 157 bsr.l b1238_fix ;test for bug1238 case 158 159 move.l USER_FPSR(a6),FPSR_SHADOW(a6) 160 or.l #sx_mask,E_BYTE(a6) 161 movem.l USER_DA(a6),d0-d1/a0-a1 162 fmovem.x USER_FP0(a6),fp0-fp3 163 fmovem.l USER_FPCR(a6),fpcr/fpsr/fpiar 164 frestore (a7)+ 165 unlk a6 166 bra.l fpsp_done 167 e1_set: 168 movem.l USER_DA(a6),d0-d1/a0-a1 169 fmovem.x USER_FP0(a6),fp0-fp3 170 fmovem.l USER_FPCR(a6),fpcr/fpsr/fpiar 171 unlk a6 172 bra.l fpsp_done 173 174 * 175 * ovf_adj 176 * 177 ovf_adj: 178 * 179 * Have a0 point to the correct operand. 180 * 181 btst.b #E3,E_BYTE(a6) ;test E3 bit 182 beq.b ovf_e1 183 184 lea WBTEMP(a6),a0 185 bra.b ovf_com 186 ovf_e1: 187 lea ETEMP(a6),a0 188 189 ovf_com: 190 bclr.b #sign_bit,LOCAL_EX(a0) 191 sne LOCAL_SGN(a0) 192 193 bsr.l g_opcls ;returns opclass in d0 194 cmpi.w #3,d0 ;check for opclass3 195 bne.b not_opc011 196 197 * 198 * FPSR_CC is saved and restored because ovf_r_x3 affects it. The 199 * CCs are defined to be 'not affected' for the opclass3 instruction. 200 * 201 move.b FPSR_CC(a6),L_SCR1(a6) 202 bsr.l ovf_r_x3 ;returns a0 pointing to result 203 move.b L_SCR1(a6),FPSR_CC(a6) 204 bra.l store ;stores to memory or register 205 206 not_opc011: 207 bsr.l ovf_r_x2 ;returns a0 pointing to result 208 bra.l store ;stores to memory or register 209 210 end 211
Indexes created Wed Oct 29 18:09:52 GMT 2025