diff options
Diffstat (limited to 'arch/m68k/fpsp040/x_ovfl.S')
| -rw-r--r-- | arch/m68k/fpsp040/x_ovfl.S | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/arch/m68k/fpsp040/x_ovfl.S b/arch/m68k/fpsp040/x_ovfl.S new file mode 100644 index 00000000000..22cb8b42c7b --- /dev/null +++ b/arch/m68k/fpsp040/x_ovfl.S @@ -0,0 +1,186 @@ +| +| x_ovfl.sa 3.5 7/1/91 +| +| fpsp_ovfl --- FPSP handler for overflow exception +| +| Overflow occurs when a floating-point intermediate result is +| too large to be represented in a floating-point data register, +| or when storing to memory, the contents of a floating-point +| data register are too large to be represented in the +| destination format. +| +| Trap disabled results +| +| If the instruction is move_out, then garbage is stored in the +| destination. If the instruction is not move_out, then the +| destination is not affected. For 68881 compatibility, the +| following values should be stored at the destination, based +| on the current rounding mode: +| +| RN Infinity with the sign of the intermediate result. +| RZ Largest magnitude number, with the sign of the +| intermediate result. +| RM For pos overflow, the largest pos number. For neg overflow, +| -infinity +| RP For pos overflow, +infinity. For neg overflow, the largest +| neg number +| +| Trap enabled results +| All trap disabled code applies. In addition the exceptional +| operand needs to be made available to the users exception handler +| with a bias of $6000 subtracted from the exponent. +| +| + +| Copyright (C) Motorola, Inc. 1990 +| All Rights Reserved +| +| THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA +| The copyright notice above does not evidence any +| actual or intended publication of such source code. + +X_OVFL: |idnt 2,1 | Motorola 040 Floating Point Software Package + + |section 8 + +#include "fpsp.h" + + |xref ovf_r_x2 + |xref ovf_r_x3 + |xref store + |xref real_ovfl + |xref real_inex + |xref fpsp_done + |xref g_opcls + |xref b1238_fix + + .global fpsp_ovfl +fpsp_ovfl: + link %a6,#-LOCAL_SIZE + fsave -(%a7) + moveml %d0-%d1/%a0-%a1,USER_DA(%a6) + fmovemx %fp0-%fp3,USER_FP0(%a6) + fmoveml %fpcr/%fpsr/%fpiar,USER_FPCR(%a6) + +| +| The 040 doesn't set the AINEX bit in the FPSR, the following +| line temporarily rectifies this error. +| + bsetb #ainex_bit,FPSR_AEXCEPT(%a6) +| + bsrl ovf_adj |denormalize, round & store interm op +| +| if overflow traps not enabled check for inexact exception +| + btstb #ovfl_bit,FPCR_ENABLE(%a6) + beqs ck_inex +| + btstb #E3,E_BYTE(%a6) + beqs no_e3_1 + bfextu CMDREG3B(%a6){#6:#3},%d0 |get dest reg no + bclrb %d0,FPR_DIRTY_BITS(%a6) |clr dest dirty bit + bsrl b1238_fix + movel USER_FPSR(%a6),FPSR_SHADOW(%a6) + orl #sx_mask,E_BYTE(%a6) +no_e3_1: + moveml USER_DA(%a6),%d0-%d1/%a0-%a1 + fmovemx USER_FP0(%a6),%fp0-%fp3 + fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar + frestore (%a7)+ + unlk %a6 + bral real_ovfl +| +| It is possible to have either inex2 or inex1 exceptions with the +| ovfl. If the inex enable bit is set in the FPCR, and either +| inex2 or inex1 occurred, we must clean up and branch to the +| real inex handler. +| +ck_inex: +| move.b FPCR_ENABLE(%a6),%d0 +| and.b FPSR_EXCEPT(%a6),%d0 +| andi.b #$3,%d0 + btstb #inex2_bit,FPCR_ENABLE(%a6) + beqs ovfl_exit +| +| Inexact enabled and reported, and we must take an inexact exception. +| +take_inex: + btstb #E3,E_BYTE(%a6) + beqs no_e3_2 + bfextu CMDREG3B(%a6){#6:#3},%d0 |get dest reg no + bclrb %d0,FPR_DIRTY_BITS(%a6) |clr dest dirty bit + bsrl b1238_fix + movel USER_FPSR(%a6),FPSR_SHADOW(%a6) + orl #sx_mask,E_BYTE(%a6) +no_e3_2: + moveb #INEX_VEC,EXC_VEC+1(%a6) + moveml USER_DA(%a6),%d0-%d1/%a0-%a1 + fmovemx USER_FP0(%a6),%fp0-%fp3 + fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar + frestore (%a7)+ + unlk %a6 + bral real_inex + +ovfl_exit: + bclrb #E3,E_BYTE(%a6) |test and clear E3 bit + beqs e1_set +| +| Clear dirty bit on dest resister in the frame before branching +| to b1238_fix. +| + bfextu CMDREG3B(%a6){#6:#3},%d0 |get dest reg no + bclrb %d0,FPR_DIRTY_BITS(%a6) |clr dest dirty bit + bsrl b1238_fix |test for bug1238 case + + movel USER_FPSR(%a6),FPSR_SHADOW(%a6) + orl #sx_mask,E_BYTE(%a6) + moveml USER_DA(%a6),%d0-%d1/%a0-%a1 + fmovemx USER_FP0(%a6),%fp0-%fp3 + fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar + frestore (%a7)+ + unlk %a6 + bral fpsp_done +e1_set: + moveml USER_DA(%a6),%d0-%d1/%a0-%a1 + fmovemx USER_FP0(%a6),%fp0-%fp3 + fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar + unlk %a6 + bral fpsp_done + +| +| ovf_adj +| +ovf_adj: +| +| Have a0 point to the correct operand. +| + btstb #E3,E_BYTE(%a6) |test E3 bit + beqs ovf_e1 + + lea WBTEMP(%a6),%a0 + bras ovf_com +ovf_e1: + lea ETEMP(%a6),%a0 + +ovf_com: + bclrb #sign_bit,LOCAL_EX(%a0) + sne LOCAL_SGN(%a0) + + bsrl g_opcls |returns opclass in d0 + cmpiw #3,%d0 |check for opclass3 + bnes not_opc011 + +| +| FPSR_CC is saved and restored because ovf_r_x3 affects it. The +| CCs are defined to be 'not affected' for the opclass3 instruction. +| + moveb FPSR_CC(%a6),L_SCR1(%a6) + bsrl ovf_r_x3 |returns a0 pointing to result + moveb L_SCR1(%a6),FPSR_CC(%a6) + bral store |stores to memory or register + +not_opc011: + bsrl ovf_r_x2 |returns a0 pointing to result + bral store |stores to memory or register + + |end |