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

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * Copyright (C) 1999-2000 Hewlett-Packard Co
   4 * Copyright (C) 1999-2000 David Mosberger-Tang <davidm@hpl.hp.com>
   5 *
   6 * 64-bit integer division.
   7 *
   8 * This code is based on the application note entitled "Divide, Square Root
   9 * and Remainder Algorithms for the IA-64 Architecture".  This document
  10 * is available as Intel document number 248725-002 or via the web at
  11 * http://developer.intel.com/software/opensource/numerics/
  12 *
  13 * For more details on the theory behind these algorithms, see "IA-64
  14 * and Elementary Functions" by Peter Markstein; HP Professional Books
  15 * (http://www.goodreads.com/book/show/2019887.Ia_64_and_Elementary_Functions)
  16 */
  17
  18#include <asm/asmmacro.h>
  19#include <asm/export.h>
  20
  21#ifdef MODULO
  22# define OP     mod
  23#else
  24# define OP     div
  25#endif
  26
  27#ifdef UNSIGNED
  28# define SGN    u
  29# define INT_TO_FP(a,b) fcvt.xuf.s1 a=b
  30# define FP_TO_INT(a,b) fcvt.fxu.trunc.s1 a=b
  31#else
  32# define SGN
  33# define INT_TO_FP(a,b) fcvt.xf a=b
  34# define FP_TO_INT(a,b) fcvt.fx.trunc.s1 a=b
  35#endif
  36
  37#define PASTE1(a,b)     a##b
  38#define PASTE(a,b)      PASTE1(a,b)
  39#define NAME            PASTE(PASTE(__,SGN),PASTE(OP,di3))
  40
  41GLOBAL_ENTRY(NAME)
  42        .regstk 2,0,0,0
  43        // Transfer inputs to FP registers.
  44        setf.sig f8 = in0
  45        setf.sig f9 = in1
  46        ;;
  47        // Convert the inputs to FP, to avoid FP software-assist faults.
  48        INT_TO_FP(f8, f8)
  49        INT_TO_FP(f9, f9)
  50        ;;
  51        frcpa.s1 f11, p6 = f8, f9       // y0 = frcpa(b)
  52        ;;
  53(p6)    fmpy.s1 f7 = f8, f11            // q0 = a*y0
  54(p6)    fnma.s1 f6 = f9, f11, f1        // e0 = -b*y0 + 1
  55        ;;
  56(p6)    fma.s1 f10 = f7, f6, f7         // q1 = q0*e0 + q0
  57(p6)    fmpy.s1 f7 = f6, f6             // e1 = e0*e0
  58        ;;
  59#ifdef MODULO
  60        sub in1 = r0, in1               // in1 = -b
  61#endif
  62(p6)    fma.s1 f10 = f10, f7, f10       // q2 = q1*e1 + q1
  63(p6)    fma.s1 f6 = f11, f6, f11        // y1 = y0*e0 + y0
  64        ;;
  65(p6)    fma.s1 f6 = f6, f7, f6          // y2 = y1*e1 + y1
  66(p6)    fnma.s1 f7 = f9, f10, f8        // r = -b*q2 + a
  67        ;;
  68#ifdef MODULO
  69        setf.sig f8 = in0               // f8 = a
  70        setf.sig f9 = in1               // f9 = -b
  71#endif
  72(p6)    fma.s1 f11 = f7, f6, f10        // q3 = r*y2 + q2
  73        ;;
  74        FP_TO_INT(f11, f11)             // q = trunc(q3)
  75        ;;
  76#ifdef MODULO
  77        xma.l f11 = f11, f9, f8         // r = q*(-b) + a
  78        ;;
  79#endif
  80        getf.sig r8 = f11               // transfer result to result register
  81        br.ret.sptk.many rp
  82END(NAME)
  83EXPORT_SYMBOL(NAME)
  84