svgtopt/gfx2d/src/GfxMultiply.s
author hgs
Wed, 03 Nov 2010 18:56:10 +0200
changeset 46 88edb906c587
permissions -rw-r--r--
201044
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/*
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* Copyright (c) 2003 Nokia Corporation and/or its subsidiary(-ies).
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* All rights reserved.
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* This component and the accompanying materials are made available
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* under the terms of "Eclipse Public License v1.0"
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* which accompanies this distribution, and is available
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* at the URL "http://www.eclipse.org/legal/epl-v10.html".
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*
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* Initial Contributors:
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* Nokia Corporation - initial contribution.
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*
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* Contributors:
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*
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* Description:  Graphics Extension Library source file
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 *
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*/
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@ 
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@   GfxMultiplyAsm - Multiply a 16:16 fixed point factor into iValue.
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@
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@       This function multiplies a 16:16 fixed point factor into iValue using
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@   an ARM 64 bit multiply instruction.  This is much faster than using the
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@   Symbian TInt64 class.  Note that iValue MUST be the first data member of
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@   this class.
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@
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@       r0 = Pointer to iValue (First data item in TFixPt class).
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@       r1 = Second factor to multiply.
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        .align  2
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        .globl  GfxMultiplyAsm__6TFixPti
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        .thumb_func
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        .code   16
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GfxMultiplyAsm__6TFixPti:
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        add     r2, pc, #4            @ Switch from Thumb to ARM execution.
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        bx      r2
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        nop
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        .align  2
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        .code   32
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        ldr     r2, [r0]              @ r2 = *this, r1 = aVal.iValue.
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        smull   r3, r2, r1, r2        @ r2:r3 = iValue * aVal.iValue.
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        mov     r2, r2, lsl #16
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        orr     r2, r2, r3, lsr #16   @ Extract middle 32 bits from 64 bit product.
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        str     r2, [r0]              @ Store into iValue.
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        bx      lr
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