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495 lines
16 KiB
Plaintext
495 lines
16 KiB
Plaintext
;
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; File: GenExcept.a
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;
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; Contains: Routines to detect reportable exceptions
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;
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; Originally Written by: Motorola Inc.
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; Adapted to Apple/MPW: Jon Okada
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;
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; Copyright: © 1990-1993 by Apple Computer, Inc., all rights reserved.
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;
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; This file is used in these builds: Mac32
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;
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; Change History (most recent first):
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;
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; <SM2> 2/3/93 CSS Update from Horror:
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; <H2> 12/21/91 jmp (BG,Z4) (for JOkada) Installed workaround for erratum 0d43b #43
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; (FP corruption with denorm) under label "do_restore:".
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; ———————————————————————————————————————————————————————————————————————————————————————
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; Pre-Horror ROM comments begin here.
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; ———————————————————————————————————————————————————————————————————————————————————————
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; <3> 6/24/91 BG Folded in Motorola version 2.0 bug fix for FPR dirty
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; bits mistakenly written over. Cleared NMCEXC and NMNEXC bits in D50D busy stack frame
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; construction. Corrected the construction of CMDREG3B
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; structure from CMDREG1B structure. Added call to 'getcmdreg3b' for E3 exceptions below
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; label 'loop2'.
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; <2> 3/30/91 BG Rolling in Jon Okada's latest changes.
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; <1> 12/14/90 BG First checked into TERROR/BBS.
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;
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; genexcept.a
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; Based upon Motorola file 'gen_except.sa'.
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; CHANGE LOG
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; 04 Jan 91 JPO Changed jump table 'exc_tbl' to contain 16-bit addresses
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; relative to table top. Changed 'bra fpsp_done' to 'rte'.
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; Modified branching to trace exception handler.
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; 07 Jun 91 JPO Folded in Motorola version 2.0 bug fix for FPR dirty
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; bits mistakenly written over.
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; 13 Jun 91 JPO Cleared NMCEXC and NMNEXC bits in D50D busy stack frame
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; construction. Corrected the construction of CMDREG3B
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; structure from CMDREG1B structure.
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; 18 Jun 91 JPO Added call to 'getcmdreg3b' for E3 exceptions below
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; label 'loop2'.
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; 11 Dec 91 JPO Installed workaround for erratum 0d43b #43 (FP corruption
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; with denorm) under label "do_restore:".
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;
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*
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* gen_except.sa 3.4 4/26/91
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*
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* gen_except --- FPSP routine to detect reportable exceptions
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*
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* This routine compares the exception enable byte of the
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* user_fpcr on the stack with the exception status byte
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* of the user_fpsr.
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*
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* Any routine which may report an exceptions must load
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* the stack frame in memory with the exceptional operand(s).
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*
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* Priority for exceptions is:
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*
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* Highest: bsun
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* snan
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* operr
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* ovfl
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* unfl
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* dz
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* inex2
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* Lowest: inex1
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*
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* Note: The IEEE standard specifies that inex2 is to be
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* reported if ovfl occurs and the ovfl enable bit is not
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* set but the inex2 enable bit is.
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*
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*
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* Copyright (C) Motorola, Inc. 1990
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* All Rights Reserved
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*
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* THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
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* The copyright notice above does not evidence any
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* actual or intended publication of such source code.
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* GEN_EXCEPT IDNT 2,1 Motorola 040 Floating Point Software Package
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exc_tbl: ; modified <1/4/91, JPO>
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dc.w bsun_exc-exc_tbl
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dc.w commonE1-exc_tbl
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dc.w commonE1-exc_tbl
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dc.w ovfl_unfl-exc_tbl
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dc.w ovfl_unfl-exc_tbl
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dc.w commonE1-exc_tbl
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dc.w commonE3-exc_tbl
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dc.w commonE3-exc_tbl
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dc.w no_match-exc_tbl
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gen_except:
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cmpi.b #IDLE_SIZE-4,1(a7) ;test for idle frame
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beq.w do_check ;go handle idle frame
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cmpi.b #UNIMP_40_SIZE-4,1(a7) ;test for orig unimp frame
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beq.b unimp_x ;go handle unimp frame
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cmpi.b #UNIMP_41_SIZE-4,1(a7) ;test for rev unimp frame
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beq.b unimp_x ;go handle unimp frame
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cmpi.b #BUSY_SIZE-4,1(a7) ;if size <> $60, fmt error
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bne fpsp_fmt_error
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lea.l BUSY_SIZE+LOCAL_SIZE(a7),a1 ;init a1 so fpsp.h
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* ;equates will work
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* Fix up the new busy frame with entries from the unimp frame
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*
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move.l ETEMP_EX(a6),ETEMP_EX(a1) ;copy etemp from unimp
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move.l ETEMP_HI(a6),ETEMP_HI(a1) ;frame to busy frame
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move.l ETEMP_LO(a6),ETEMP_LO(a1)
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move.l CMDREG1B(a6),CMDREG1B(a1) ;set inst in frame to unimp
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; move.l CMDREG1B(a6),d0 ;fix cmd1b to make it - DELETED <6/13/91, JPO> <T3>
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; and.l #$03800000,d0 ;work for cmd3b - DELETED <6/13/91, JPO> <T3>
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bsr.b getcmdreg3b ; map cmd1b format into cmd3b <6/13/91, JPO> <T3>
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move.l d0,CMDREG3B(a1) ;in the busy frame
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*
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* Or in the FPSR from the emulation with the USER_FPSR on the stack.
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*
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fmove.l FPSR,d0
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or.l d0,USER_FPSR(a6)
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move.l USER_FPSR(a6),FPSR_SHADOW(a1) ;set exc bits
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or.l #sx_mask,E_BYTE(a1)
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bra do_clean
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;
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; Subroutine getcmdreg3b converts longword at CMDREG1B(a6) into CMDREG3B <T3> thru next <T3>
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; format and returns it in d0. Uses: d1
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;
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getcmdreg3b:
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move.l CMDREG1B(a6),d0 ; d0 <- CMDREG1B
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and.l #$03ff0000,d0 ; isolate interesting 10 bits
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bfextu d0{10:4},d1 ; extract bit field to rotate
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lsr.b #1,d1 ; rotate it
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bcc.b @1
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bset.l #3,d1
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@1:
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bfins d1,d0{10:4} ; insert rotated field back into d0
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rts ; return with d0.hi in cmd3b format <T3>
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*
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* Frame is an unimp frame possible resulting from an fmove <ea>,fp0
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* that caused an exception
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*
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* a1 is modified to point into the new frame allowing fpsp equates
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* to be valid.
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*
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unimp_x:
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cmpi.b #UNIMP_40_SIZE-4,1(a7) ;test for orig unimp frame
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bne.b test_rev
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lea.l UNIMP_40_SIZE+LOCAL_SIZE(a7),a1
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bra.b unimp_con
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test_rev:
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cmpi.b #UNIMP_41_SIZE-4,1(a7) ;test for rev unimp frame
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bne fpsp_fmt_error ;if not $28 or $30
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lea.l UNIMP_41_SIZE+LOCAL_SIZE(a7),a1
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unimp_con:
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*
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* Fix up the new unimp frame with entries from the old unimp frame
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*
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move.l CMDREG1B(a6),CMDREG1B(a1) ;set inst in frame to unimp
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*
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* Or in the FPSR from the emulation with the USER_FPSR on the stack.
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*
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fmove.l FPSR,d0
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or.l d0,USER_FPSR(a6)
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bra do_clean
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*
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* Frame is idle, so check for exceptions reported through
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* USER_FPSR and set the unimp frame accordingly.
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* A7 must be incremented to the point before the
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* idle fsave vector to the unimp vector.
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*
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do_check:
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add.l #4,A7 ;point A7 back to unimp frame
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*
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* Or in the FPSR from the emulation with the USER_FPSR on the stack.
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*
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fmove.l FPSR,d0
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or.l d0,USER_FPSR(a6)
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*
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* On a busy frame, we must clear the nmnexc bits.
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*
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cmpi.b #BUSY_SIZE-4,1(a7) ;check frame type
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bne.b check_fr ;if busy, clr nmnexc
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clr.w NMNEXC(a6) ;clr nmnexc & nmcexc
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btst.b #5,CMDREG1B(a6) ;test for fmove out
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bne.b check_fr
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move.l USER_FPSR(a6),FPSR_SHADOW(a6) ;set exc bits
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or.l #sx_mask,E_BYTE(a6)
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check_fr:
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move.b FPCR_ENABLE(a6),d0 ;get fpcr enable byte
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and.b FPSR_EXCEPT(a6),d0 ;and in the fpsr exc byte
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bfffo d0{24:8},d1 ;test for first set bit
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lea.l exc_tbl,a0 ;load jmp table address
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subi.b #24,d1 ;normalize bit offset to 0-8
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; move.l (a0,d1.w*4),a0 ;load routine address based
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* ;on first enabled exc - deleted <1/4/91, JPO>
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adda.w (a0,d1.w*2),a0 ; calculate routine addr <1/4/91, JPO>
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jmp (a0) ;jump to routine
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*
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* Bsun is not possible in unimp or unsupp
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*
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bsun_exc:
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bra do_clean
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*
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* The typical work to be done to the unimp frame to report an
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* exception is to set the E1/E3 byte and clr the U flag.
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* commonE1 does this for E1 exceptions, which are snan,
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* operr, and dz. commonE3 does this for E3 exceptions, which
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* are inex2 and inex1, and also clears the E1 exception bit
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* left over from the unimp exception.
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*
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commonE1:
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bset.b #E1,E_BYTE(a6) ;set E1 flag
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bra.b commonE ;go clean and exit
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commonE3:
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tst.b UFLG_TMP(a6) ;test flag for unsup/unimp state
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bne.b unsE3
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uniE3:
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bset.b #E3,E_BYTE(a6) ;set E3 flag
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bclr.b #E1,E_BYTE(a6) ;clr E1 from unimp
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bra.b commonE
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unsE3:
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tst.b RES_FLG(a6)
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bne.b unsE3_0
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unsE3_1:
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bset.b #E3,E_BYTE(a6) ;set E3 flag
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unsE3_0:
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bclr.b #E1,E_BYTE(a6) ;clr E1 flag
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; move.l CMDREG1B(a6),d0 ;fix cmd1b to make it - DELETED <6/13/91, JPO> <T3>
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; and.l #$03800000,d0 ;work for cmd3b - DELETED <6/13/91, JPO> <T3>
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bsr getcmdreg3b ; map cmd1b format into cmd3b <6/13/91, JPO> <T3>
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move.l d0,CMDREG3B(a6) ;in the busy frame
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commonE:
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bclr.b #UFLAG,T_BYTE(a6) ;clr U flag from unimp
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bra.w do_clean ;go clean and exit
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*
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* No bits in the enable byte match existing exceptions. Check for
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* the case of the ovfl exc without the ovfl enabled, but with
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* inex2 enabled.
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*
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no_match:
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btst.b #inex2_bit,FPCR_ENABLE(a6) ;check for ovfl/inex2 case
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beq.b no_exc ;if clear, exit
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btst.b #ovfl_bit,FPSR_EXCEPT(a6) ;now check ovfl
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beq.b no_exc ;if clear, exit
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bra.b ovfl_unfl ;go to unfl_ovfl to determine if
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* ;it is an unsupp or unimp exception
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* No exceptions are to be reported. If the instruction was
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* unimplemented, no FPU restore is necessary. If it was
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* unsupported, we must perform the restore.
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no_exc:
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tst.b UFLG_TMP(a6) ;test flag for unsupp/unimp state
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beq.b uni_no_exc
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uns_no_exc:
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tst.b RES_FLG(a6) ;check if frestore is needed
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bne.w do_clean ;if clear, no frestore needed
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uni_no_exc:
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movem.l USER_DA(a6),d0-d1/a0-a1
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fmovem.x USER_FP0(a6),fp0-fp3
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fmovem.l USER_FPCR(a6),fpcr/fpsr/fpiar
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unlk a6
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bra finish_up
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*
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* Unsupported Data Type Handler:
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* Ovfl:
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* An fmoveout that results in an overflow is reported this way.
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* Unfl:
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* An fmoveout that results in an underflow is reported this way.
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*
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* Unimplemented Instruction Handler:
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* Ovfl:
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* Only scosh, setox, ssinh, stwotox, and scale can set overflow in
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* this manner.
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* Unfl:
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* Stwotox, setox, and scale can set underflow in this manner.
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* Any of the other Library Routines such that f(x)=x in which
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* x is an extended denorm can report an underflow exception.
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* It is the responsibility of the exception-causing exception
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* to make sure that WBTEMP is correct.
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*
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* The exceptional operand is in FP_SCR1.
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*
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ovfl_unfl:
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tst.b UFLG_TMP(a6) ;test flag for unsupp/unimp state
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beq.b ofuf_con
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*
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* The caller was from an unsupported data type trap. Test if the
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* caller set CU_ONLY. If so, the exceptional operand is expected in
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* FPTEMP, rather than WBTEMP.
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*
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tst.b CU_ONLY(a6) ;test if inst is cu-only
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beq.b unsE3
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* move.w #$fe,CU_SAVEPC(a6) ; DELETED <6/7/91, JPO> <T3>
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clr.b CU_SAVEPC(a6) ; ADDED <6/7/91, JPO> <T3>
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bset.b #E1,E_BYTE(a6) ;set E1 exception flag
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move.w ETEMP_EX(a6),FPTEMP_EX(a6)
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move.l ETEMP_HI(a6),FPTEMP_HI(a6)
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move.l ETEMP_LO(a6),FPTEMP_LO(a6)
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bset.b #fptemp15_bit,DTAG(a6) ;set fpte15
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bclr.b #UFLAG,T_BYTE(a6) ;clr U flag from unimp
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bra.b do_clean ;go clean and exit
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ofuf_con:
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move.b (a7),VER_TMP(a6) ;save version number
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cmpi.b #BUSY_SIZE-4,1(a7) ;check for busy frame
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beq.b busy_fr ;if unimp, grow to busy
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cmpi.b #VER_40,(a7) ;test for orig unimp frame
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bne.b try_41 ;if not, test for rev frame
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moveq.l #13,d0 ;need to zero 14 lwords
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bra.b ofuf_fin
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try_41:
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cmpi.b #VER_41,(a7) ;test for rev unimp frame
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bne fpsp_fmt_error ;if neither, exit with error
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moveq.l #11,d0 ;need to zero 12 lwords
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clr.w NMNEXC(a6) ; clr nmnexc and nmcexc bits <6/13/91, JPO> <T3>
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ofuf_fin:
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clr.l (a7)
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loop1:
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clr.l -(a7) ;clear and dec a7
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dbra.w d0,loop1
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move.b VER_TMP(a6),(a7)
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move.b #BUSY_SIZE-4,1(a7) ;write busy fmt word.
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busy_fr:
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move.l FP_SCR1(a6),WBTEMP_EX(a6) ;write
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move.l FP_SCR1+4(a6),WBTEMP_HI(a6) ;execptional op to
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move.l FP_SCR1+8(a6),WBTEMP_LO(a6) ;wbtemp
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bset.b #E3,E_BYTE(a6) ;set E3 flag
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bclr.b #E1,E_BYTE(a6) ;make sure E1 is clear
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bclr.b #UFLAG,T_BYTE(a6) ;clr U flag
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move.l USER_FPSR(a6),FPSR_SHADOW(a6)
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or.l #sx_mask,E_BYTE(a6)
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; move.l CMDREG1B(a6),d0 ;fix cmd1b to make it - DELETED <6/13/91, JPO> <T3>
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; and.l #$03800000,d0 ;work for cmd3b - <6/13/91, JPO> <T3>
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bsr getcmdreg3b ; map cmd1b format into cmd3b <6/13/91, JPO> <T3>
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move.l d0,CMDREG3B(a6) ;in the busy frame
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*
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* Check if the frame to be restored is busy or unimp.
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*** NOTE *** Bug fix for errata (0d43b #3)
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* If the frame is unimp, we must create a busy frame to
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* fix the bug with the nmnexc bits in cases in which they
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* are set by a previous instruction and not cleared by
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* the save. The frame will be unimp only if the final
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* instruction in an emulation routine caused the exception
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* by doing an fmove <ea>,fp0. The exception operand, in
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* internal format, is in fptemp.
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*
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do_clean:
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cmpi.b #UNIMP_40_SIZE-4,1(a7)
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bne.b do_con
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moveq.l #13,d0 ;in orig, need to zero 14 lwords
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bra.b do_build
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do_con:
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cmpi.b #UNIMP_41_SIZE-4,1(a7)
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bne.b do_restore ;frame must be busy
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moveq.l #11,d0 ;in rev, need to zero 12 lwords
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clr.w NMNEXC(a6) ; clr nmnexc and nmcexc bits <6/13/91, JPO> <T3>
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do_build:
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move.b (a7),VER_TMP(a6)
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clr.l (a7)
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loop2:
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clr.l -(a7) ;clear and dec a7
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dbra.w d0,loop2
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*
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* Use a1 as pointer into new frame. a6 is not correct if an unimp or
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* busy frame was created as the result of an exception on the final
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* instruction of an emulation routine.
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*
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* We need to set the nmcexc bits if the exception is E1. Otherwise,
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* the exc taken will be inex2.
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*
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lea.l BUSY_SIZE+LOCAL_SIZE(a7),a1 ;init a1 for new frame
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move.b VER_TMP(a6),(a7) ;write busy fmt word
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move.b #BUSY_SIZE-4,1(a7)
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move.l FP_SCR1(a6),WBTEMP_EX(a1) ;write
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move.l FP_SCR1+4(a6),WBTEMP_HI(a1) ;exceptional op to
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move.l FP_SCR1+8(a6),WBTEMP_LO(a1) ;wbtemp
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btst.b #E1,E_BYTE(a1)
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; beq.b do_restore ; DELETED <6/18/91> <T3>
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bne.b @1 ; E1 exception <6/18/91> <T3>
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bsr getcmdreg3b ; E3 exception requires CMDREG3B <6/18/91> <T3>
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move.l d0,CMDREG3B(a1) ; <6/18/91> <T3>
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bra.b do_restore ; <6/18/91> <T3>
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@1: ; E1 exception - label ADDED <6/18/91> <T3>
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bfextu USER_FPSR(a6){17:4},d0 ;get snan/operr/ovfl/unfl bits
|
|
bfins d0,NMCEXC(a1){4:4} ;and insert them in nmcexc
|
|
move.l USER_FPSR(a6),FPSR_SHADOW(a1) ;set exc bits
|
|
or.l #sx_mask,E_BYTE(a1)
|
|
|
|
do_restore:
|
|
movem.l USER_DA(a6),d0-d1/a0-a1
|
|
fmovem.x USER_FP0(a6),fp0-fp3
|
|
fmovem.l USER_FPCR(a6),fpcr/fpsr/fpiar
|
|
frestore (a7)+
|
|
|
|
;<SM2> CSS
|
|
; Workaround fix for D50D erratum F31 (0d43b #43) which occurs if the restored state is for
|
|
; a restart of an operation with an extended denormal source operand (unsupported data
|
|
; type) followed by a FMOVE/FABS/FNEG reg,reg. This sequence may lead to an incorrect
|
|
; tag for the destination of the FMOVE/FABS/FNEG. The workaround involves inserting an
|
|
; FSAVE immediately after the FRESTORE. If the FSAVE is not idle, bit ETE15 in byte
|
|
; STAG in the FSAVE frame is cleared; if the FSAVE is idle, an unimplemented frame of
|
|
; all zeros is built. The frame is then restored via FRESTORE. This fix is for 68040
|
|
; mask versions D50D and later, which have an unimplemented FSAVE frame of length $30.
|
|
; <12/11/91, JPO>
|
|
; begin workaround <12/11/91, JPO>
|
|
fsave -(a7) ; save state which was just restored
|
|
tst.b 1(a7) ; busy or unimp frame?
|
|
bne.b @clrete15 ; yes
|
|
|
|
tst.b (a7) ; null frame?
|
|
beq.b @restor2 ; yes. done
|
|
|
|
clr.l (a7) ; idle frame: construct blank unimp frame
|
|
moveq #10,d0 ; use D0 as counter
|
|
@unimplp:
|
|
clr.l -(a7) ; loop pushes 11 longwords of zero
|
|
dbra.w d0,@unimplp
|
|
|
|
move.l #$41300000,-(a7) ; push D50D idle frame header longword
|
|
move.l USER_DA(a6),d0 ; restore user's D0 value
|
|
bra.b @restor2 ; done
|
|
|
|
@clrete15: ; busy or unimp frame
|
|
bclr.b #etemp15_bit,STAG(a6) ; clear ETE15 bit in frame
|
|
|
|
@restor2:
|
|
frestore (a7)+ ; 2nd FRESTORE ends workaround <12/11/91, JPO>
|
|
|
|
unlk a6
|
|
*
|
|
* If trace mode enabled, then go to trace handler. This handler
|
|
* cannot have any fp instructions. If there are fp inst's and an
|
|
* exception has been restored into the machine then the exception
|
|
* will occur upon execution of the fp inst. This is not desirable
|
|
* in the kernel (supervisor mode). See MC68040 manual Section 9.3.8.
|
|
*
|
|
finish_up:
|
|
btst.b #7,(a7) ;test T1 in SR
|
|
bne.b g_trace
|
|
btst.b #6,(a7) ;test T0 in SR
|
|
bne.b g_trace
|
|
; bra fpsp_done ; deleted <1/4/91, JPO>
|
|
rte ; <1/4/91, JPO>
|
|
*
|
|
* Change integer stack to look like trace stack
|
|
* The address of the instruction that caused the
|
|
* exception is already in the integer stack (is
|
|
* the same as the saved friar)
|
|
*
|
|
* If the current frame is already a 6-word stack then all
|
|
* that needs to be done is to change the vector# to TRACE.
|
|
* If the frame is only a 4-word stack (meaning we got here
|
|
* on an Unsupported data type exception), then we need to grow
|
|
* the stack an extra 2 words and get the FPIAR from the FPU.
|
|
*
|
|
g_trace:
|
|
bftst EXC_VEC-4(sp){0:4}
|
|
bne.b g_easy
|
|
|
|
sub.w #4,sp ;make room
|
|
move.l 4(sp),(sp)
|
|
move.l 8(sp),4(sp)
|
|
sub.w #BUSY_SIZE,sp
|
|
fsave (sp)
|
|
fmove fpiar,BUSY_SIZE+EXC_EA-4(sp)
|
|
frestore (sp)
|
|
add.w #BUSY_SIZE,sp
|
|
|
|
g_easy:
|
|
move.w #TRACE_VEC,EXC_VEC-4(a7)
|
|
; bra real_trace ; deleted <1/4/91, JPO>
|
|
move.l ($0024).W,-(sp) ; push trace exception handler vector <1/4/91, JPO>
|
|
rts ; branch to trace exception handler <1/4/91, JPO>
|
|
*
|
|
|
|
|