51 lines
1.3 KiB
NASM
51 lines
1.3 KiB
NASM
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;Copyright (C) Manx Software Systems, Inc. 1987. All rights reserved.
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; :ts=8
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include lmacros.h
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dataseg segment word public 'data'
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public chop_ctl, round_ctl, rdown_ctl
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chop_ctl dw 0fbfH ;control word for Chop mode
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round_ctl dw 03bfH ;control word for Round nearest mode
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rdown_ctl dw 07bfh ;control word for Round Down mode
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mess db "8087/80287 is absent or not functional!"
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db 10 ; newline
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MESSLEN equ 40
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dataseg ends
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public $maxdigit ; this must be in CODESEG
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$maxdigit dw 16 ;maximum # of digits for ftoa() to produce.
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assume ds:dataseg
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public _chk87_, $fltinit
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$fltinit proc
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_chk87_:
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push bp
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mov bp,sp
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sub sp,2
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fninit
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fnstcw word ptr -2[bp]
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mov cx,50
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w1loop: loop w1loop ; wait for a while
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and word ptr -2[bp],01f3fh ; clear unused bits
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cmp word ptr -2[bp],0033fh ; is 8087 there?
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jnz notthere ; no, return error to caller
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fstsw word ptr -2[bp]
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mov cx,50
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w2loop: loop w2loop ; wait for a while
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test word ptr -2[bp],0b8bfh ; all status bits should be off
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jz ok_8087 ; 8087 is there!!
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notthere:
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stc ;bad status, no 8087 present
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jmp short exit
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ok_8087:
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;note: the carry is cleared by the test instr. above
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fldcw word ptr round_ctl ;set initial control
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exit:
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mov sp,bp
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pop bp
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ret
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$fltinit endp
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finish
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end
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