84 строки
2.0 KiB
ArmAsm
84 строки
2.0 KiB
ArmAsm
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/*
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* Copyright (C) 2000 Hewlett-Packard Co
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* Copyright (C) 2000 David Mosberger-Tang <davidm@hpl.hp.com>
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*
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* 32-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 EXTEND zxt4
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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 EXTEND sxt4
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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,si3))
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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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mov r2 = 0xffdd // r2 = -34 + 65535 (fp reg format bias)
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EXTEND in0 = in0 // in0 = a
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EXTEND in1 = in1 // in1 = b
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;;
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setf.sig f8 = in0
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setf.sig f9 = in1
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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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;;
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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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setf.exp f7 = r2 // f7 = 2^-34
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frcpa.s1 f6, p6 = f8, f9 // y0 = frcpa(b)
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;;
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(p6) fmpy.s1 f8 = f8, f6 // q0 = a*y0
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(p6) fnma.s1 f6 = f9, f6, f1 // e0 = -b*y0 + 1
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;;
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#ifdef MODULO
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setf.sig f9 = in1 // f9 = -b
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#endif
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(p6) fma.s1 f8 = f6, f8, f8 // q1 = e0*q0 + q0
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(p6) fma.s1 f6 = f6, f6, f7 // e1 = e0*e0 + 2^-34
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;;
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#ifdef MODULO
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setf.sig f7 = in0
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#endif
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(p6) fma.s1 f6 = f6, f8, f8 // q2 = e1*q1 + q1
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;;
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FP_TO_INT(f6, f6) // q = trunc(q2)
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;;
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#ifdef MODULO
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xma.l f6 = f6, f9, f7 // r = q*(-b) + a
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;;
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#endif
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getf.sig r8 = f6 // transfer result to result register
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br.ret.sptk.many rp
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END(NAME)
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