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62 lines
1.7 KiB
62 lines
1.7 KiB
; GPFix.inc - definitions for GP exception handler code
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; usage -
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; 1) include gpfix.inc
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; 2) bracket critical code with "beg_fault_trap handler" and
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; "end_fault_trap"
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; 3) define a handler entry point where execution should continue
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; a) this must be in the same code segment as the faulty code
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; b) two extra words (fault IP/fault) will be pushed on the stack when
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; an exception occurs. They should be popped before continuing.
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; This can be done with the 'fault_fix_stack' macro.
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; They are there if you want to determine which instruction faulted.
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; c) This handler can do whatever it likes. Usually, it will return
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; an error code to the caller.
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; 4) if you don't want to worry about the extra values on the stack,
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; use the fix_fault_stack macro to remove them
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_bft_count = 0
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_eft_count = 0
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_bft_ macro handler, count
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_bft_&count:
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_hft_&count = handler
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endm
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;
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; Begin fault critical region. 'handler' is the address of
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; the exception handler to jmp to if a fault occurs.
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;
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beg_fault_trap macro handler
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if _bft_count - _eft_count
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.err
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%out Mismatched beg_fault_trap/end_fault_trap pairs in beg_fault_trap
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endif
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_bft_ handler, %_bft_count
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_bft_count = _bft_count + 1
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endm
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_eft_ macro count
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_eft_&count:
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_GPFIX SEGMENT
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dw seg _bft_&count, _bft_&count, _eft_&count, _hft_&count
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_GPFIX ENDS
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endm
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;
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; End fault critical region.
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;
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end_fault_trap macro
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_eft_ %_eft_count
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_eft_count = _eft_count+1
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if _bft_count - _eft_count
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.err
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%out Mismatched beg_fault_trap/end_fault_trap pairs in end_fault_trap
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endif
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endm
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;
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; Clean up stack in fault handler.
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;
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fault_fix_stack macro
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add sp, 4
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endm
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