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| gen_except.sa 3.7 1/16/92
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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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| Copyright (C) Motorola, Inc. 1990
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| All Rights Reserved
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|
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| For details on the license for this file, please see the
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| file, README, in this same directory.
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|
GEN_EXCEPT: |idnt 2,1 | Motorola 040 Floating Point Software Package
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|section 8
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#include "fpsp.h"
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|
|xref real_trace
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|xref fpsp_done
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|xref fpsp_fmt_error
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exc_tbl:
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.long bsun_exc
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.long commonE1
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.long commonE1
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.long ovfl_unfl
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.long ovfl_unfl
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.long commonE1
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.long commonE3
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.long commonE3
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.long no_match
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.global gen_except
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gen_except:
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cmpib #IDLE_SIZE-4,1(%a7) |test for idle frame
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beq do_check |go handle idle frame
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cmpib #UNIMP_40_SIZE-4,1(%a7) |test for orig unimp frame
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beqs unimp_x |go handle unimp frame
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cmpib #UNIMP_41_SIZE-4,1(%a7) |test for rev unimp frame
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beqs unimp_x |go handle unimp frame
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cmpib #BUSY_SIZE-4,1(%a7) |if size <> $60, fmt error
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bnel fpsp_fmt_error
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leal 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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movel ETEMP_EX(%a6),ETEMP_EX(%a1) |copy etemp from unimp
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movel ETEMP_HI(%a6),ETEMP_HI(%a1) |frame to busy frame
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movel ETEMP_LO(%a6),ETEMP_LO(%a1)
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movel CMDREG1B(%a6),CMDREG1B(%a1) |set inst in frame to unimp
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movel CMDREG1B(%a6),%d0 |fix cmd1b to make it
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andl #0x03c30000,%d0 |work for cmd3b
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bfextu CMDREG1B(%a6){#13:#1},%d1 |extract bit 2
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lsll #5,%d1
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swap %d1
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orl %d1,%d0 |put it in the right place
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bfextu CMDREG1B(%a6){#10:#3},%d1 |extract bit 3,4,5
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lsll #2,%d1
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swap %d1
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orl %d1,%d0 |put them in the right place
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movel %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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fmovel %FPSR,%d0
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orl %d0,USER_FPSR(%a6)
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movel USER_FPSR(%a6),FPSR_SHADOW(%a1) |set exc bits
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orl #sx_mask,E_BYTE(%a1)
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bra do_clean
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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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| a1 is modified to point into the new frame allowing fpsp equates
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| to be valid.
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unimp_x:
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cmpib #UNIMP_40_SIZE-4,1(%a7) |test for orig unimp frame
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bnes test_rev
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leal UNIMP_40_SIZE+LOCAL_SIZE(%a7),%a1
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bras unimp_con
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test_rev:
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cmpib #UNIMP_41_SIZE-4,1(%a7) |test for rev unimp frame
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bnel fpsp_fmt_error |if not $28 or $30
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leal UNIMP_41_SIZE+LOCAL_SIZE(%a7),%a1
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unimp_con:
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| Fix up the new unimp frame with entries from the old unimp frame
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movel CMDREG1B(%a6),CMDREG1B(%a1) |set inst in frame to unimp
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| Or in the FPSR from the emulation with the USER_FPSR on the stack.
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fmovel %FPSR,%d0
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orl %d0,USER_FPSR(%a6)
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bra do_clean
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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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do_check:
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addl #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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fmovel %FPSR,%d0
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orl %d0,USER_FPSR(%a6)
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| On a busy frame, we must clear the nmnexc bits.
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cmpib #BUSY_SIZE-4,1(%a7) |check frame type
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bnes check_fr |if busy, clr nmnexc
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clrw NMNEXC(%a6) |clr nmnexc & nmcexc
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btstb #5,CMDREG1B(%a6) |test for fmove out
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bnes frame_com
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movel USER_FPSR(%a6),FPSR_SHADOW(%a6) |set exc bits
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orl #sx_mask,E_BYTE(%a6)
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bras frame_com
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check_fr:
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cmpb #UNIMP_40_SIZE-4,1(%a7)
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beqs frame_com
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clrw NMNEXC(%a6)
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frame_com:
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moveb FPCR_ENABLE(%a6),%d0 |get fpcr enable byte
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andb 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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leal exc_tbl,%a0 |load jmp table address
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subib #24,%d1 |normalize bit offset to 0-8
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movel (%a0,%d1.w*4),%a0 |load routine address based
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| ;based on first enabled exc
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jmp (%a0) |jump to routine
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| Bsun is not possible in unimp or unsupp
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bsun_exc:
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bra do_clean
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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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commonE1:
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bsetb #E1,E_BYTE(%a6) |set E1 flag
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bra commonE |go clean and exit
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commonE3:
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tstb UFLG_TMP(%a6) |test flag for unsup/unimp state
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bnes unsE3
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uniE3:
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bsetb #E3,E_BYTE(%a6) |set E3 flag
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bclrb #E1,E_BYTE(%a6) |clr E1 from unimp
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bra commonE
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unsE3:
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tstb RES_FLG(%a6)
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bnes unsE3_0
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unsE3_1:
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bsetb #E3,E_BYTE(%a6) |set E3 flag
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unsE3_0:
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bclrb #E1,E_BYTE(%a6) |clr E1 flag
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movel CMDREG1B(%a6),%d0
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andl #0x03c30000,%d0 |work for cmd3b
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bfextu CMDREG1B(%a6){#13:#1},%d1 |extract bit 2
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lsll #5,%d1
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swap %d1
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orl %d1,%d0 |put it in the right place
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bfextu CMDREG1B(%a6){#10:#3},%d1 |extract bit 3,4,5
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lsll #2,%d1
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swap %d1
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orl %d1,%d0 |put them in the right place
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movel %d0,CMDREG3B(%a6) |in the busy frame
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commonE:
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bclrb #UFLAG,T_BYTE(%a6) |clr U flag from unimp
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bra do_clean |go clean and exit
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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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no_match:
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btstb #inex2_bit,FPCR_ENABLE(%a6) |check for ovfl/inex2 case
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beqs no_exc |if clear, exit
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btstb #ovfl_bit,FPSR_EXCEPT(%a6) |now check ovfl
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beqs no_exc |if clear, exit
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bras ovfl_unfl |go to unfl_ovfl to determine if
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| ;it is an unsupp or unimp exc
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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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tstb UFLG_TMP(%a6) |test flag for unsupp/unimp state
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beqs uni_no_exc
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uns_no_exc:
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tstb RES_FLG(%a6) |check if frestore is needed
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bne do_clean |if clear, no frestore needed
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uni_no_exc:
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moveml USER_DA(%a6),%d0-%d1/%a0-%a1
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fmovemx USER_FP0(%a6),%fp0-%fp3
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fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
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unlk %a6
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bra finish_up
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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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| 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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| The exceptional operand is in FP_SCR1.
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ovfl_unfl:
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tstb UFLG_TMP(%a6) |test flag for unsupp/unimp state
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beqs ofuf_con
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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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tstb CU_ONLY(%a6) |test if inst is cu-only
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beq unsE3
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| move.w #$fe,CU_SAVEPC(%a6)
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clrb CU_SAVEPC(%a6)
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bsetb #E1,E_BYTE(%a6) |set E1 exception flag
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movew ETEMP_EX(%a6),FPTEMP_EX(%a6)
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movel ETEMP_HI(%a6),FPTEMP_HI(%a6)
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movel ETEMP_LO(%a6),FPTEMP_LO(%a6)
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bsetb #fptemp15_bit,DTAG(%a6) |set fpte15
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bclrb #UFLAG,T_BYTE(%a6) |clr U flag from unimp
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bra do_clean |go clean and exit
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ofuf_con:
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moveb (%a7),VER_TMP(%a6) |save version number
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cmpib #BUSY_SIZE-4,1(%a7) |check for busy frame
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beqs busy_fr |if unimp, grow to busy
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cmpib #VER_40,(%a7) |test for orig unimp frame
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bnes try_41 |if not, test for rev frame
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moveql #13,%d0 |need to zero 14 lwords
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bras ofuf_fin
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try_41:
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cmpib #VER_41,(%a7) |test for rev unimp frame
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bnel fpsp_fmt_error |if neither, exit with error
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moveql #11,%d0 |need to zero 12 lwords
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ofuf_fin:
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clrl (%a7)
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loop1:
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clrl -(%a7) |clear and dec a7
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dbra %d0,loop1
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moveb VER_TMP(%a6),(%a7)
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moveb #BUSY_SIZE-4,1(%a7) |write busy fmt word.
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busy_fr:
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movel FP_SCR1(%a6),WBTEMP_EX(%a6) |write
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movel FP_SCR1+4(%a6),WBTEMP_HI(%a6) |exceptional op to
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movel FP_SCR1+8(%a6),WBTEMP_LO(%a6) |wbtemp
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bsetb #E3,E_BYTE(%a6) |set E3 flag
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bclrb #E1,E_BYTE(%a6) |make sure E1 is clear
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bclrb #UFLAG,T_BYTE(%a6) |clr U flag
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movel USER_FPSR(%a6),FPSR_SHADOW(%a6)
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orl #sx_mask,E_BYTE(%a6)
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movel CMDREG1B(%a6),%d0 |fix cmd1b to make it
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andl #0x03c30000,%d0 |work for cmd3b
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bfextu CMDREG1B(%a6){#13:#1},%d1 |extract bit 2
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lsll #5,%d1
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swap %d1
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orl %d1,%d0 |put it in the right place
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bfextu CMDREG1B(%a6){#10:#3},%d1 |extract bit 3,4,5
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lsll #2,%d1
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swap %d1
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orl %d1,%d0 |put them in the right place
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movel %d0,CMDREG3B(%a6) |in the busy frame
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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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do_clean:
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cmpib #UNIMP_40_SIZE-4,1(%a7)
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bnes do_con
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moveql #13,%d0 |in orig, need to zero 14 lwords
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bras do_build
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do_con:
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cmpib #UNIMP_41_SIZE-4,1(%a7)
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bnes do_restore |frame must be busy
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moveql #11,%d0 |in rev, need to zero 12 lwords
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do_build:
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moveb (%a7),VER_TMP(%a6)
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clrl (%a7)
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loop2:
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clrl -(%a7) |clear and dec a7
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dbra %d0,loop2
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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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| 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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leal BUSY_SIZE+LOCAL_SIZE(%a7),%a1 |init a1 for new frame
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moveb VER_TMP(%a6),(%a7) |write busy fmt word
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moveb #BUSY_SIZE-4,1(%a7)
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movel FP_SCR1(%a6),WBTEMP_EX(%a1) |write
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movel FP_SCR1+4(%a6),WBTEMP_HI(%a1) |exceptional op to
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movel 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
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bfextu USER_FPSR(%a6){#17:#4},%d0 |get snan/operr/ovfl/unfl bits
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bfins %d0,NMCEXC(%a1){#4:#4} |and insert them in nmcexc
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movel USER_FPSR(%a6),FPSR_SHADOW(%a1) |set exc bits
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orl #sx_mask,E_BYTE(%a1)
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do_restore:
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moveml USER_DA(%a6),%d0-%d1/%a0-%a1
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fmovemx USER_FP0(%a6),%fp0-%fp3
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fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
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frestore (%a7)+
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tstb RES_FLG(%a6) |RES_FLG indicates a "continuation" frame
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beq cont
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bsr bug1384
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cont:
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unlk %a6
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| If trace mode enabled, then go to trace handler. This handler
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| cannot have any fp instructions. If there are fp inst's and an
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| exception has been restored into the machine then the exception
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| will occur upon execution of the fp inst. This is not desirable
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| in the kernel (supervisor mode). See MC68040 manual Section 9.3.8.
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finish_up:
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btstb #7,(%a7) |test T1 in SR
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bnes g_trace
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btstb #6,(%a7) |test T0 in SR
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bnes g_trace
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bral fpsp_done
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| Change integer stack to look like trace stack
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| The address of the instruction that caused the
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| exception is already in the integer stack (is
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| the same as the saved friar)
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| If the current frame is already a 6-word stack then all
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| that needs to be done is to change the vector# to TRACE.
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| If the frame is only a 4-word stack (meaning we got here
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| on an Unsupported data type exception), then we need to grow
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| the stack an extra 2 words and get the FPIAR from the FPU.
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g_trace:
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bftst EXC_VEC-4(%sp){#0:#4}
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bne g_easy
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subw #4,%sp | make room
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movel 4(%sp),(%sp)
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movel 8(%sp),4(%sp)
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subw #BUSY_SIZE,%sp
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fsave (%sp)
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fmovel %fpiar,BUSY_SIZE+EXC_EA-4(%sp)
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frestore (%sp)
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addw #BUSY_SIZE,%sp
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g_easy:
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movew #TRACE_VEC,EXC_VEC-4(%a7)
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bral real_trace
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| This is a work-around for hardware bug 1384.
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bug1384:
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link %a5,#0
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fsave -(%sp)
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cmpib #0x41,(%sp) | check for correct frame
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beq frame_41
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bgt nofix | if more advanced mask, do nada
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frame_40:
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tstb 1(%sp) | check to see if idle
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bne notidle
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idle40:
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clrl (%sp) | get rid of old fsave frame
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movel %d1,USER_D1(%a6) | save d1
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movew #8,%d1 | place unimp frame instead
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loop40: clrl -(%sp)
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dbra %d1,loop40
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movel USER_D1(%a6),%d1 | restore d1
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movel #0x40280000,-(%sp)
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frestore (%sp)+
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unlk %a5
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rts
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frame_41:
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tstb 1(%sp) | check to see if idle
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bne notidle
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idle41:
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clrl (%sp) | get rid of old fsave frame
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movel %d1,USER_D1(%a6) | save d1
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movew #10,%d1 | place unimp frame instead
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loop41: clrl -(%sp)
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dbra %d1,loop41
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movel USER_D1(%a6),%d1 | restore d1
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movel #0x41300000,-(%sp)
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frestore (%sp)+
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unlk %a5
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rts
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notidle:
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bclrb #etemp15_bit,-40(%a5)
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frestore (%sp)+
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unlk %a5
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rts
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nofix:
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frestore (%sp)+
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unlk %a5
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rts
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|end
|
