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102 lines
2.6 KiB
C++
102 lines
2.6 KiB
C++
// Emacs style mode select -*- C++ -*-
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//-----------------------------------------------------------------------------
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//
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// $Id:$
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//
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// Copyright (C) 1993-1996 by id Software, Inc.
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//
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// This source is available for distribution and/or modification
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// only under the terms of the DOOM Source Code License as
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// published by id Software. All rights reserved.
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//
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// The source is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code License
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// for more details.
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//
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// DESCRIPTION:
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// Fixed point arithemtics, implementation.
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//
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//-----------------------------------------------------------------------------
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#ifndef __M_FIXED__
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#define __M_FIXED__
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#include "doomtype.h"
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//
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// Fixed point, 32bit as 16.16.
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//
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#define FRACBITS 16
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#define FRACUNIT (1<<FRACBITS)
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typedef int fixed_t;
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fixed_t
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#ifndef _MSC_VER
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STACK_ARGS
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#endif
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FixedMul_ASM (fixed_t a, fixed_t b);
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fixed_t STACK_ARGS FixedDiv_ASM (fixed_t a, fixed_t b);
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fixed_t FixedMul_C (fixed_t a, fixed_t b);
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fixed_t FixedDiv_C (fixed_t a, fixed_t b);
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#ifdef USEASM
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#ifdef DJGPP
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// killough 5/10/98: In djgpp, use inlined assembly for performance
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__inline__ static fixed_t FixedMul(fixed_t a, fixed_t b)
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{
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fixed_t result;
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asm(" imull %2 ;"
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" shrdl $16,%%edx,%0 ;"
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: "=a,=a" (result) // eax is always the result
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: "0,0" (a), // eax is also first operand
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"m,r" (b) // second operand can be mem or reg
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: "%edx", "%cc" // edx and condition codes clobbered
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);
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return result;
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}
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// killough 5/10/98: In djgpp, use inlined assembly for performance
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__inline__ static fixed_t FixedDiv(fixed_t a, fixed_t b)
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{
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fixed_t result;
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if (abs(a) >> 14 >= abs(b))
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return (a^b)<0 ? MININT : MAXINT;
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asm(" movl %0, %%edx ;"
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" sall $16,%%eax ;"
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" sarl $16,%%edx ;"
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" idivl %2 ;"
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: "=a,=a" (result) // eax is always the result
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: "0,0" (a), // eax is also the first operand
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"m,r" (b) // second operand can be mem or reg (not imm)
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: "%edx", "%cc" // edx and condition codes are clobbered
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);
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return result;
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}
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#else // DJGPP
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#define FixedMul(a,b) FixedMul_ASM(a,b)
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#define FixedDiv(a,b) FixedDiv_ASM(a,b)
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#endif // DJGPP
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#else // USEASM
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#define FixedMul(a,b) FixedMul_C(a,b)
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#define FixedDiv(a,b) FixedDiv_C(a,b)
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#endif
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#endif
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//-----------------------------------------------------------------------------
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//
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// $Log:$
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//
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//-----------------------------------------------------------------------------
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