; By: Jeffrey Nonken page 60,132 .286 _text segment byte public 'code' _text ends _data segment word public 'data' _data ends const segment word public 'const' const ends _bss segment word public 'bss' _bss ends dgroup group const, _bss, _data assume cs: _text, ds: nothing _data segment word public 'data' even env_8087 dw 47 dup (?) norm_8087 dw 177fh _data ends _text segment byte public 'code' ; ; This code saves the 80x87 enviroment and sets up our own. First, this ; assumes you are running an 80287; the 8087 may require more FWAIT ; operations. Second, I decided that I didn't want to handle exceptions, so ; I simply disabled them. That means that if the 80x87 gets an invalid result ; (such as divide-by-zero) the 80x87 will continue to run and will produce ; invalid results until the end of your current calculation. Anything that ; depends on the results will, of course, also be invalid. If you want ; exceptions to be handled, get documentation for the 80x87 and you will ; see how to set norm_8087 (above) to suit your needs. If you are running ; an 8087 and don't know where to put FWAIT instructions, you can always ; add one after each floating-point instruction. NOTE: FWAIT is synonymous ; to WAIT. They are the same instruction. ; ; This was written for TURBO C and will also work with MSC. It should work ; with any programming language with no more than minor changes in the ; label names or the interface. Consult your compiler manual for more detail. ; I wrote this so it would work with either the tiny or small models. ; Actually, it will probably work with any of the models. You should be ; able to assemble this with MASM and link it right in. ; ; extern save_8087(); ; extern restore_8087(); ; public _save_8087 _save_8087 proc near cli ; no interruptions! lea bx,dgroup:env_8087 ; point to save area fwait ; make sure processor is ready fnsave [bx] ; save the 8087 environment lea bx,dgroup:norm_8087 ; point to our new 8087 setup mov ax,[bx] ; get it fldcw [bx] ; set it fwait sti ; restore interrupts ret _save_8087 endp public _restore_8087 _restore_8087 proc near cli ; no interruptions! lea bx,dgroup:env_8087 ; point to saved 8087 stuff frstor [bx] ; restore the 8087 environment sti ; restore interrupts ret _restore_8087 endp _text ends end