156 lines
3.9 KiB
NASM
156 lines
3.9 KiB
NASM
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page ,132
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title 87fmod - fmod function
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;***
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;87fmod.asm - fmod function (8087/emulator version)
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;
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; Copyright (c) 1984-2001, Microsoft Corporation. All rights reserved.
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;
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;Purpose:
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; Implements fmod() library function for computing floating-point
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; remainder. Uses FPREM 8087 instruction or its emulated equivalent.
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;
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;Revision History:
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; 12-09-84 GFW Added copyright message
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; 05-12-85 GFW Changed fmod(x,0) = 0 for System V.2 compatibility
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; 10-15-86 GFW In-line instructions rather than call _fpmath
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; 05-08-87 BCM Added intrinsic version (_CIfmod)
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; 10-12-87 BCM OS/2 support C library changes
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; Including pascal naming and calling conv. & no _fac
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; 01-18-88 BCM Eliminated IBMC20 switches; ifos2,noos2 ==> ifmt,nomt
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; OS2_SUPPORT ==> MTHREAD
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; 08-26-88 WAJ 386 version.
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; 08-17-90 WAJ Now uses _stdcall.
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; 05-17-91 WAJ Added _STDCALL ifdefs.
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; 03-04-92 GDP Changed behavior for INF args
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; 03-22-92 GDP Fixed bug: removed fxch out of the remloop
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; 09-22-93 SKS Removed obsolete _FIamod (no longer needed by FORTRAN)
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; 12-09-94 JWM Modified fFMOD to test for bogus Pentiums and call an FPREM workaround
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; 12-13-94 SKS Correct spelling of _adjust_fdiv
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; 10-15-95 BWT Don't do _adjust_fdiv test for NT.
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;
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;*******************************************************************************
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.xlist
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include cruntime.inc
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include mrt386.inc
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include elem87.inc
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.list
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.data
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ifndef NT_BUILD
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extrn _adjust_fdiv:dword
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endif
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jmptab OP_FMOD,4,<'fmod',0,0>,<0,0,0,0,0,0>,2
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DNCPTR codeoffset fFMOD ; 0000 NOS Valid non-0, TOS Valid non-0
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DNCPTR codeoffset _rtindfpop ; 0001 NOS Valid non-0, TOS 0
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DNCPTR codeoffset _tosnan2 ; 0010 NOS Valid non-0, TOS NAN
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DNCPTR codeoffset _rtindfpop ; 0011 NOS Valid non-0, TOS Inf
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DNCPTR codeoffset _rtzeropop ; 0100 NOS 0, TOS Valid non-0
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DNCPTR codeoffset _rtindfpop ; 0101 NOS 0, TOS 0
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DNCPTR codeoffset _tosnan2 ; 0110 NOS 0, TOS NAN
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DNCPTR codeoffset _rtindfpop ; 0111 NOS 0, TOS Inf
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DNCPTR codeoffset _nosnan2 ; 1000 NOS NAN, TOS Valid non-0
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DNCPTR codeoffset _nosnan2 ; 1001 NOS NAN, TOS 0
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DNCPTR codeoffset _nan2 ; 1010 NOS NAN, TOS NAN
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DNCPTR codeoffset _nosnan2 ; 1011 NOS NAN, TOS Inf
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DNCPTR codeoffset _rtindfpop ; 1100 NOS Inf, TOS Valid non-0
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DNCPTR codeoffset _rtindfpop ; 1101 NOS Inf, TOS 0
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DNCPTR codeoffset _tosnan2 ; 1110 NOS Inf, TOS NAN
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DNCPTR codeoffset _rtindfpop ; 1111 NOS Inf, TOS Inf
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page
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CODESEG
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extrn _ctrandisp2:near
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extrn _cintrindisp2:near
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extrn _rtindfpop:near
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extrn _rtnospop:near
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extrn _rtzeropop:near
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extrn _tosnan2:near
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extrn _nosnan2:near
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extrn _nan2:near
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ifndef NT_BUILD
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extrn _adj_fprem:near
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endif
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.386
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;***
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;fFMOD - floating-point remainder (8087/emulator intrinsic version)
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;Purpose:
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; fmod(x,y) computes floating-point remainder of x/y, i.e. the
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; floating-point number f such that x = iy + f where f and x have
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; the same sign, and |f| < |y|, and i is an integer.
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;
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; Uses the FPREM instruction to compute the remainder.
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; (Formerly used FDIV.)
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;
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;Entry:
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; floating-point numerator in ST(1)
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; floating-point denominator in ST(0)
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;
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;Exit:
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; floating-point result in ST(0);
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; (pops one of the arguments, replaces the other with the result)
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;
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;Uses:
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; AX, Flags.
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;
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;Exceptions:
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; fmod(x, 0.0) currently returns 0.0 -- see System V specification
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;*******************************************************************************
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public fmod
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fmod proc
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mov edx, OFFSET _OP_FMODjmptab
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jmp _ctrandisp2
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fmod endp
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public _CIfmod
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_CIfmod proc
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mov edx, OFFSET _OP_FMODjmptab
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jmp _cintrindisp2
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_CIfmod endp
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lab fFMOD
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fxch
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lab remloop
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ifdef NT_BUILD ; NT handles the P5 bug in the OS
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fprem ; do fprem's until reduction is done
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else
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cmp _adjust_fdiv, 1
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jz badP5_fprem
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fprem ; do fprem's until reduction is done
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jmp fprem_done
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lab badP5_fprem
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call _adj_fprem
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lab fprem_done
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endif
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fstsw ax
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fwait
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sahf ; load fprem flags into flags
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JSPE remloop ; not done with range reduction
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fstp st(1) ; get rid of divisor
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ret
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end
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