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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/ia64/lib/idiv64.S
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/*

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 * Copyright (C) 1999-2000 Hewlett-Packard Co

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 * Copyright (C) 1999-2000 David Mosberger-Tang <[email protected]>

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 *

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 * 64-bit integer division.

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 *

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 * This code is based on the application note entitled "Divide, Square Root

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 * and Remainder Algorithms for the IA-64 Architecture".  This document

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 * is available as Intel document number 248725-002 or via the web at

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 * http://developer.intel.com/software/opensource/numerics/

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 *

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 * For more details on the theory behind these algorithms, see "IA-64

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 * and Elementary Functions" by Peter Markstein; HP Professional Books

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 * (http://www.hp.com/go/retailbooks/)

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 */

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#include <asm/asmmacro.h>

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#ifdef MODULO

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# define OP	mod

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#else

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# define OP	div

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#endif

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#ifdef UNSIGNED

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# define SGN	u

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# define INT_TO_FP(a,b)	fcvt.xuf.s1 a=b

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# define FP_TO_INT(a,b)	fcvt.fxu.trunc.s1 a=b

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#else

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# define SGN

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# define INT_TO_FP(a,b)	fcvt.xf a=b

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# define FP_TO_INT(a,b)	fcvt.fx.trunc.s1 a=b

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#endif

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#define PASTE1(a,b)	a##b

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#define PASTE(a,b)	PASTE1(a,b)

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#define NAME		PASTE(PASTE(__,SGN),PASTE(OP,di3))

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GLOBAL_ENTRY(NAME)

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	.regstk 2,0,0,0

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	// Transfer inputs to FP registers.

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	setf.sig f8 = in0

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	setf.sig f9 = in1

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	;;

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	// Convert the inputs to FP, to avoid FP software-assist faults.

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	INT_TO_FP(f8, f8)

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	INT_TO_FP(f9, f9)

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	;;

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	frcpa.s1 f11, p6 = f8, f9	// y0 = frcpa(b)

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	;;

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(p6)	fmpy.s1 f7 = f8, f11		// q0 = a*y0

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(p6)	fnma.s1 f6 = f9, f11, f1	// e0 = -b*y0 + 1

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	;;

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(p6)	fma.s1 f10 = f7, f6, f7		// q1 = q0*e0 + q0

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(p6)	fmpy.s1 f7 = f6, f6		// e1 = e0*e0

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	;;

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#ifdef MODULO

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	sub in1 = r0, in1		// in1 = -b

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#endif

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(p6)	fma.s1 f10 = f10, f7, f10	// q2 = q1*e1 + q1

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(p6)	fma.s1 f6 = f11, f6, f11	// y1 = y0*e0 + y0

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	;;

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(p6)	fma.s1 f6 = f6, f7, f6		// y2 = y1*e1 + y1

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(p6)	fnma.s1 f7 = f9, f10, f8	// r = -b*q2 + a

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	;;

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#ifdef MODULO

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	setf.sig f8 = in0		// f8 = a

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	setf.sig f9 = in1		// f9 = -b

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#endif

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(p6)	fma.s1 f11 = f7, f6, f10	// q3 = r*y2 + q2

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	;;

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	FP_TO_INT(f11, f11)		// q = trunc(q3)

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	;;

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#ifdef MODULO

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	xma.l f11 = f11, f9, f8		// r = q*(-b) + a

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	;;

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#endif

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	getf.sig r8 = f11		// transfer result to result register

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	br.ret.sptk.many rp

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END(NAME)

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