LXR linux/arch/ia64/lib/idiv64.S

   1/*
   2 * Copyright (C) 1999-2000 Hewlett-Packard Co
   3 * Copyright (C) 1999-2000 David Mosberger-Tang <davidm@hpl.hp.com>
   4 *
   5 * 64-bit integer division.
   6 *
   7 * This code is based on the application note entitled "Divide, Square Root
   8 * and Remainder Algorithms for the IA-64 Architecture".  This document
   9 * is available as Intel document number 248725-002 or via the web at
  10 * http://developer.intel.com/software/opensource/numerics/
  11 *
  12 * For more details on the theory behind these algorithms, see "IA-64
  13 * and Elementary Functions" by Peter Markstein; HP Professional Books
  14 * (http://www.hp.com/go/retailbooks/)
  15 */
  16
  17#include <asm/asmmacro.h>
  18
  19#ifdef MODULO
  20# define OP     mod
  21#else
  22# define OP     div
  23#endif
  24
  25#ifdef UNSIGNED
  26# define SGN    u
  27# define INT_TO_FP(a,b) fcvt.xuf.s1 a=b
  28# define FP_TO_INT(a,b) fcvt.fxu.trunc.s1 a=b
  29#else
  30# define SGN
  31# define INT_TO_FP(a,b) fcvt.xf a=b
  32# define FP_TO_INT(a,b) fcvt.fx.trunc.s1 a=b
  33#endif
  34
  35#define PASTE1(a,b)     a##b
  36#define PASTE(a,b)      PASTE1(a,b)
  37#define NAME            PASTE(PASTE(__,SGN),PASTE(OP,di3))
  38
  39GLOBAL_ENTRY(NAME)
  40        .regstk 2,0,0,0
  41        // Transfer inputs to FP registers.
  42        setf.sig f8 = in0
  43        setf.sig f9 = in1
  44        ;;
  45        // Convert the inputs to FP, to avoid FP software-assist faults.
  46        INT_TO_FP(f8, f8)
  47        INT_TO_FP(f9, f9)
  48        ;;
  49        frcpa.s1 f11, p6 = f8, f9       // y0 = frcpa(b)
  50        ;;
  51(p6)    fmpy.s1 f7 = f8, f11            // q0 = a*y0
  52(p6)    fnma.s1 f6 = f9, f11, f1        // e0 = -b*y0 + 1
  53        ;;
  54(p6)    fma.s1 f10 = f7, f6, f7         // q1 = q0*e0 + q0
  55(p6)    fmpy.s1 f7 = f6, f6             // e1 = e0*e0
  56        ;;
  57#ifdef MODULO
  58        sub in1 = r0, in1               // in1 = -b
  59#endif
  60(p6)    fma.s1 f10 = f10, f7, f10       // q2 = q1*e1 + q1
  61(p6)    fma.s1 f6 = f11, f6, f11        // y1 = y0*e0 + y0
  62        ;;
  63(p6)    fma.s1 f6 = f6, f7, f6          // y2 = y1*e1 + y1
  64(p6)    fnma.s1 f7 = f9, f10, f8        // r = -b*q2 + a
  65        ;;
  66#ifdef MODULO
  67        setf.sig f8 = in0               // f8 = a
  68        setf.sig f9 = in1               // f9 = -b
  69#endif
  70(p6)    fma.s1 f11 = f7, f6, f10        // q3 = r*y2 + q2
  71        ;;
  72        FP_TO_INT(f11, f11)             // q = trunc(q3)
  73        ;;
  74#ifdef MODULO
  75        xma.l f11 = f11, f9, f8         // r = q*(-b) + a
  76        ;;
  77#endif
  78        getf.sig r8 = f11               // transfer result to result register
  79        br.ret.sptk.many rp
  80END(NAME)
  81