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Assembly Source File | 1994-06-17 | 16.6 KB | 366 lines

; Created 10/01/90 ; Updated 03/20/92 ; To restore status of control word to QBASIC defaults ; Revised 10/06/92 ; Added routine to check for 80C287A ; Revised 06/30/93 ; Better handle old PC's with an 8087 ; Revised 12/07/93 ; More info on control flags, results of testing Cyrix 80387SX chip ; Revised 03/29/94 ; More info on control bits, testing Cyrix 486D - 486DX clone ; Updated 06/06/94 more info on purpose of port 0F0h ;====================================================================== ; Copyright (C) Copr. 1990, 1991, 1992, 93, 94 by Sidney J. Kelly ; All Rights Reserved. ; Sidney J. Kelly ; 150 Woodhaven Drive ; Pittsburgh, PA 15228 ; home phone 412-561-0950 (7pm to 9:30pm EST) ;====================================================================== ;;;;«RM82»«TS8,16,24,32,40,48,56» DOSSEG .MODEL MEDIUM, BASIC .CODE ;====================================================================== ; DECLARE FUNCTION CHECK87%() ; Returns: ; 0 if no 80x87, or system equipment bit not set for 80x87. ; 87 if an 8087 ; -87 if 8087 emulation in use on an 80286 or 80386. Because the ; the 80287 has almost exactly the same instruction set as the ; 8087 few have felt a need to emulate the 80287. The 80827 ; just includes one new instruction (protected mode), ; nothing for use in real mode. 80387 has transendental ; math routines. (Note: real mode software math chip emulators will ; not work with protected mode software without hugh speed penalties). ; 287 if an 80827 (note on early 386SX, an 80287 was allowed) ; 1287 if an 80C287A/80287XL (an 80287 with the 80387 instruction set) ; 387 if an 80387, 80387SX or 80486DX. ; Because of 486SX not all 486's will have a math chip. ; The 80387/80486DX is much faster than an 80287 because it does ; not need the FWAIT's before every instruction ; ; More accurate than just checking the equipment word. ; QBX, Version 7 and QBASIC 4.5 both merely check the equipment ; word (Int 11h, 0040:0010) to determine if an 80x87 is installed. ; Therefore, changing the bit in at 0040:0010 at can be used as a ; software toggle. ; ; Because of complaints about the traditional test with inexpensive clones ; (See Jon Waterhouse letter in BYTE, Nov. 1990, page 40) routine first ; tests the equipment word in RAM bios. If the equipment bit is clear, ; then routine halts. It does not check CMOS equipment word math ; chip bit because not all clones properly record in CMOS that a math chip ; is installed (e.g. ACER 910 w/ Award BIOS only adjusts Int 11h). ; ; You should assume that if switch for NDP is not set or Int 11h does not ; show an NDP that user wanted it that way. ; ; Tested: Intel 80287, Cyrix 80387SX, software emulation of 8087, Intel 486DX ;====================================================================== ; ; REFERENCES: ; basic info is adapted from Ted Forgeron's article in PC ; Tech Journal, Aug '87 p43. ; Copr. 1987 Pat Shea - Psi! (that Copr. is on there cuz my ; lawyer sez I should, but feel ; free to hack away!!! pats.) ; In the event of subsequent republication of this function, ; please carry forward reference to these two gentlemen as ; original authors. ; Minor beautification, addition of MASM 5.1 simplified ; directives, detection of emulation, additional commentary by SJK 12/12/90 ; ; Similar code: Robert Zigon, "Interactive Bezier Curves" Tech Specialist ; V2,N3,P53 (March 1991) ; ; This code is based on code from Intel's "i486 Programmers Reference Manual" ; cpuid32.asm - Per file ; "This program has been developed by Intel Corporation. You have ; Intel's permission to incorporate this source code into your ; product royalty free." ; as modified by Wayne A. King, [CIS: 70022,2700] 5/24/93 for use w/ ; MASM 5.1, to correct bugs w/ real mode processors and 32 bit instructions ; ; The CX loop idea for slow PC's with a math chip is from the public ; domain INFOPLUS Version 1.56, Andrew Rossman 12/30/92. ;====================================================================== EVEN CTRL_Word DW 0 ; CTRL_Word word for the NDP test. Orig_CW DW 0 ; original CTRL_Word DATA1 DT 0 ; temp storage for 387 testing ; Please do not remove Copyright DB 13,10,'Copyright Copr. (C) 1990, 1991, 1994 Sidney J. Kelly',13,10 Copyright1 DB 'All Rights Reserved',13,10,26 EVEN CHECK87 PROC FAR Pushf ; save flags ;-------- ; in response to clone errors, test to see if system knows ; if math chip is installed. If Int 11h sez no, then ; report no mathchip. Can't check AT CMOS mathchip bit ; because some clones do not set the bit in the CMOS, but ; only set the bit in the Int 11h equipment word, e.g. ACER 910, during ; boot up. ;-------- Int 11h Test AL,10b ; is mathchip bit Set? JZ No_Math_Chip ; no mathchip ; Test for any mathchip Xor AX,AX ; make AX = 0 Mov Word Ptr CS:[CTRL_Word],AX ; clear CTRL_Word Out 0F0h,AX ; clear busy bit on 80287+ ; w/o changing (real/protected) mode of NDP by writing 0 to the port. ; Per "Intel486 SX Microprocessor Intel487 SX Math CoProcessor Data Book" ; (Intel 1991) ISBN 1-55512-158-6, pages 140-141, a write to this port ; acts as external device reset to clear IRQ 13 error on 80287+ chip ; an internal device reset for 80287+ requires a FNINIT ; Load a sensible default control value so NDP handles all ; exceptions. This should help prevent errors because of slow ; chips (affine, even, 64 bit precision) Mov Word Ptr CS:[Orig_CW],13BFh ; store a reasonable value ; default after FINIT on 80387 is 037Fh. After QBASIC ; tests math chip, the control word becomes 1370h ;------- ; The next 80x87 instructions cannot carry the WAIT prefix, ; because there may not be an 80x87 for which to wait. The WAIT is ; therefore emulated with a MOV CX,<value>! LOOP $ combination. This ; allow use of routine on an old PC with an 8087. ;------- FNSTCW Word Ptr CS:[Orig_CW] ; save original value ; it takes about 24 clocks for a real NDP to do this ; (about 3-5 clocks on a 486) ; it do have a chip, our "reasonable value" will be overwritten Mov CX,14h ; time waste loop Loop $ ; to substitute for a FWAIT JMP $+2 ; waste time and flush que JMP $+2 ; waste time and flush que FNINIT ; try to initialize the NDP ; it takes about 8 clocks for a real NDP to do this, 33 clocks ; for 80387, 17 clocks on a 486 ;------ ; use the no-wait state version of the op code so will not ; hang a machine without a NDP. Loop allows test of a PC that ; does have an 8087. ;------ Mov CX,14h ; a time waste loop Loop $ ; allow 8087 time to react JMP $+2 ; waste time and flush que FNSTCW CS:[CTRL_Word] ; put CTRL_Word in memory ; it takes about 24 clocks for a real NDP to do this ; 3 to 5 clocks on a 486 ;------- ; use the no-wait state version of the op code so will not ; hang a machine without a NDP. Loop allows test of a PC that ; does have an 8087. ;------- Mov CX,14h Loop $ JMP $+2 ; waste time and flush que Cmp BYTE PTR CS:[CTRL_Word+1],3 ; if high byte = 3h have NDP Je Chk_87 ; found something, so keep going No_Math_Chip: Xor AX,AX ; else zero AX to show Popf ; restore flags Ret ; end, return to main routine Chk_87: ; Test for 8087 ; we know we have a math chip now, so test if ; CPU is old 808x, 8018x, NEC V series chip Push SP Pop AX Cmp AX,SP ; SP = AX if have 80286+ chip Jne Have_87 ; else old mode chip, no emulation possible ; we now have a math chip and an 80286+ CPU And CS:[CTRL_Word],NOT 080h ; turn ON interrupts (IEM = 0) ; IEM is bit 7 of control word FLDCW CS:[CTRL_Word] ; load CTRL_Word word FDISI ; turn OFF interrupts (IEM = 1) FSTCW CS:[CTRL_Word] ; store CTRL_Word word FWAIT ; allow time for update to occur ; if IEM=1, 8087 (only 8087 pays attention to IEM) Test CS:[CTRL_Word],80h ; test IEM Jz Chk_287 ; not an 8087, test for 80287 Report_Emulation: ;----------- ; Report have 8087 emulation by software. Emulation only can be done on an ; 80286 or 80386. To get this far, CPU must be 80286+, emulating 8087 ; There is no particular advantage to emulating 80287. In addition, some ; early 80386DX and 80386SX CPU's used the 80287 chip, so can't easily test ; for emulation of an 80287 on a 386 machine. ;----------- ;--- not necessary, already tested for above ; Xor AX,AX ; clear AX ; Push AX ; put on stack ; Popf ; put in flags ; Pushf ; put back on stack ; Pop AX ; get flags back in AX ; And AX,0F000h ; clear all but upper 4 bits ; Cmp AX,0F000h ; if bits 12-15 are set then CPU ; JE Have_87 ; is not an 80286, 80386 or 80486 Mov AX,-87 ; put -87 in AX to show that Jmp SHORT Chk_87_END ; emulation is detected ;----------- ; I haven't tested the software that emulates the 80287/80387 so this is ; not tested for. Emulation of an x87 is possible ; because of a special bit (EM or Bit 2) in the 80286 machine status ; word and the use of a specific interrupt generated by 80826/80386 if ; coprocessor is not available. The 80386 also can do emulation ; using Bit 2 in register CR0 along with the use of a special interrupt ; if the coprocessor is not available. ; ; Emulators of 80387 have also become available, though not tested. ; The only reason for testing for emulation is to suggest to user that he ; would get faster results if he relied on MS QuickBasic built in ; software emulation rather than other forms of software emulation. ; Moreover, because many software emulators do not work with ; protected mode (otherwise speed penalty would be huge), emulators ; would take up space on a fast 386 machine. SJK ;----------- Have_87: ; CPU is a NEC, 8086/88 or 80186/88 Mov AX,87 ; put 87 in AX to show Jmp SHORT Chk_87_END ; no emulation is detected Chk_287: ; Test for 80287 ; if any of the following instructions is not available, Int 07h ; will call a BIOS routine that ignores the error on 80286+ in real mode ; This has been tested. Though, should only get here if have a 8087 chip ; Should not get an error in protected mode w/ 80386+ chip, because ; math chip either must exist or it must be emulated to get this far. FINIT ; set default infinity mode FLD1 ; push 1 on stack FLDZ ; push 0 on stack FDIV ; then divide. Make infinity ; by dividing 1 by zero FLD ST ; push back on stack. Change FCHS ; sign & make negative infinity FCOMPP ; compare the two infinities ; pops stack and eliminates 2 pushes ;-------- ; Default after FINIT for 80287 & 8087 is projective infinity where ; both positive and negative infinity are equal. The 80C287A ; (a faster 80287 chip with all the features of the 80387), the 80387 and ; and the 80486DX use affine infinity, and ignore projective infinity. ; Under affine infinity positive and negative infinity are at opposite ; ends of the number line and are not equal. ; (SJK - Who thinks of these things???) ;-------- FSTSW CS:[CTRL_Word] ; store status for result FWAIT ; wait until status word is stored Mov AX,CS:[CTRL_Word] ; get CTRL_Word word SAHF ; put highbyte (AH) status in flags Jnz Test_4_387 ; If bit 6 (infinity control) ; not set then it is a 80387 or 80C287A Have_287: Mov AX,287 ; else report that it is an 80287 ; since we tested for an 8087 Jmp SHORT Chk_87_END ;------------ ; NDP not an 8087 or an 80287 so it must be an 80387(80486DX) or 80C287A. ; The 80486DX/80387/80C287A ignore the infinity control (IC) flag, ; while the 80287/8087 do not. SJK ;------------ Test_4_387: ;.387 ; allows assembly of 387 instructions ; and cuts out many of the FWAITs ; if your assembler wont handle .387 then the DB equivalents ; are shown below the .387 instruction ; .387 mode code wont run on a 286 because .387 drops the FWAIT that ; preceed all the NDP instructions, a 286 needs the syncronization ; that the FWAITs provide. FLDPI ; load Pi (value in radians) ; FSIN ; take the Sin(Pi) DB 0D9h,0FEh ; the code for FSIN ; if NDP wont support op codes, 80286+ bios will capture error and ; ignore it FSTP TByte Ptr DATA1 ; store and Pop FWAIT ; wait for memory to catch up FLD TByte Ptr DATA1 ; get value back FWAIT ; wait for memory to catch up ; FCOS ; now take Cos(Sin(PI)) DB 0D9h,0FFh ; the code for FCOS ; if COS(SIN(Pi)) is calculated correctly it = 1.00, if FSIN and FCOS ; not available or don't work, then COS(SIN(Pi)) will = Pi FLD1 ; load 1 FCOMPP ; compare ST(0) with ST(1) ; pops stack and eliminates 2 pushes FSTSW CS:[CTRL_Word] ; store status for result FWAIT ; wait until status word is stored Mov AX,CS:[CTRL_Word] ; get CTRL_Word word SAHF ; place in flags JNZ Have_287 ; if not equal then have 287 chip ; distinguish between 80386 and 80286 based on flags Mov AX,0F000h ; see if 80286 or 80386 Push AX PopF PushF Pop AX And AX,0F000h JNZ Have_387 ; if not clear, quit, have 80387 Mov AX,1287 ; report have 80C287A/80287XL Jmp Short Chk_87_END Have_387: Mov AX,387 ; report have 80387 Chk_87_END: Mov Byte Ptr CS:[Orig_CW+1],00010011b ; select affine infinity, even rouding, 64 bit precision ; but don't touch lower byte since QB sets it to control ; its own exception handling FLDCW Word Ptr CS:[Orig_CW] ; re-load modified original word Popf ; restore flags Ret ; end, return to main routine CHECK87 ENDP END Math chip control word, high byte ┌──┬──┬──┬──┬──┬──┬──┬──┐ │F │E │D │C │B │A │9 │8 │ bits within high byte └┬─┴┬─┴┬─┴┬─┴┬─┴┬─┴┬─┴┬─┘ │ │ │ │ │ │ └──┴───Precision Control │ │ │ │ │ │ (00 = 24 bits) │ │ │ │ │ │ (01 = undefined) │ │ │ │ │ │ (10 = 53 bits) │ │ │ │ │ │ (11 = 64 bits) DEFAULT │ │ │ │ └──┴─────────Rounding Control │ │ │ │ (00 = Nearest or Even) DEFAULT │ │ │ │ (01 = Round Down to minus infinity) │ │ │ │ (10 = Round Up to positive infinity) │ │ │ │ (11 = Chop/truncate toward 0) │ │ │ └───────────────Infinity Control │ │ │ (0 = Projective infinity) │ │ │ Default on FINIT on 8087/80287 │ │ │ (1 = Affine infinity) QBASIC default └──┴──┴──────────────────Reserved (All 0) After FINIT, the default high byte is 03h, or Projective infinity, round nearest, 64 bits of precision QBASIC uses 13h for high byte or Affine infinity, round nearest, 64 bits of precision Low byte of control word ┌──┬──┬──┬──┬──┬──┬──┬──┐ │7 │6 │5 │4 │3 │2 │1 │0 │ bits within low byte └┬─┴┬─┴┬─┴┬─┴┬─┴┬─┴┬─┴┬─┘ │ │ │ │ │ │ │ └─── Invalid operation (IM) │ │ │ │ │ │ └────── Denormalized operation (DM) │ │ │ │ │ └───────── Divide by zero error (ZM) │ │ │ │ └──────────── Overflow (UM) │ │ │ └─────────────── Underflow (UM) │ │ └────────────────── Precision error (PM) │ └───────────────────── Reserved └──────────────────────── Interrupt enable mask (IEM) 0 = enabled 1 = disabled. Busy bit on 80287+ After FINIT, the default low byte is 7Fh, or Exceptions disabled, Interrupt mask (IEM) disabled. QBASIC uses 70h for low byte or Exceptions enabled (all but PM), Interrupt mask (IEM) disabled