LXR uboot/arch/powerpc/lib/

   1/*
   2 * This code was copied from arch/powerpc/kernel/misc_32.S in the Linux
   3 * kernel sources (commit 85e2efbb1db9a18d218006706d6e4fbeb0216213, also
   4 * known as 2.6.38-rc5).  The source file copyrights are as follows:
   5 *
   6 * (C) Copyright 1995-1996 Gary Thomas (gdt@linuxppc.org)
   7 *
   8 * Largely rewritten by Cort Dougan (cort@cs.nmt.edu)
   9 * and Paul Mackerras.
  10 *
  11 * This program is free software; you can redistribute it and/or
  12 * modify it under the terms of the GNU General Public License as
  13 * published by the Free Software Foundation; either version 2 of
  14 * the License, or (at your option) any later version.
  15 */
  16
  17#include <ppc_asm.tmpl>
  18#include <ppc_defs.h>
  19#include <config.h>
  20
  21/*
  22 * Extended precision shifts.
  23 *
  24 * Updated to be valid for shift counts from 0 to 63 inclusive.
  25 * -- Gabriel
  26 *
  27 * R3/R4 has 64 bit value
  28 * R5    has shift count
  29 * result in R3/R4
  30 *
  31 *  ashrdi3: arithmetic right shift (sign propagation)
  32 *  lshrdi3: logical right shift
  33 *  ashldi3: left shift
  34 */
  35        .globl __lshrdi3
  36__lshrdi3:
  37        subfic  r6,r5,32
  38        srw     r4,r4,r5        # LSW = count > 31 ? 0 : LSW >> count
  39        addi    r7,r5,32        # could be xori, or addi with -32
  40        slw     r6,r3,r6        # t1 = count > 31 ? 0 : MSW << (32-count)
  41        srw     r7,r3,r7        # t2 = count < 32 ? 0 : MSW >> (count-32)
  42        or      r4,r4,r6        # LSW |= t1
  43        srw     r3,r3,r5        # MSW = MSW >> count
  44        or      r4,r4,r7        # LSW |= t2
  45        blr
  46