arch/powerpc/lib/_ashldi3.S

   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  * SPDX-License-Identifier:     GPL-2.0+
  12  */
  13
  14 #include <ppc_asm.tmpl>
  15 #include <ppc_defs.h>
  16 #include <config.h>
  17
  18 /*
  19  * Extended precision shifts.
  20  *
  21  * Updated to be valid for shift counts from 0 to 63 inclusive.
  22  * -- Gabriel
  23  *
  24  * R3/R4 has 64 bit value
  25  * R5    has shift count
  26  * result in R3/R4
  27  *
  28  *  ashrdi3: arithmetic right shift (sign propagation)
  29  *  lshrdi3: logical right shift
  30  *  ashldi3: left shift
  31  */
  32         .globl __ashldi3
  33 __ashldi3:
  34         subfic  r6,r5,32
  35         slw     r3,r3,r5        # MSW = count > 31 ? 0 : MSW << count
  36         addi    r7,r5,32        # could be xori, or addi with -32
  37         srw     r6,r4,r6        # t1 = count > 31 ? 0 : LSW >> (32-count)
  38         slw     r7,r4,r7        # t2 = count < 32 ? 0 : LSW << (count-32)
  39         or      r3,r3,r6        # MSW |= t1
  40         slw     r4,r4,r5        # LSW = LSW << count
  41         or      r3,r3,r7        # MSW |= t2
  42         blr