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Tom Rini83d290c2018-05-06 17:58:06 -04001/* SPDX-License-Identifier: GPL-2.0+ */
Kyle Moffett01baa052011-02-23 06:40:38 +00002/*
3 * This code was copied from arch/powerpc/kernel/misc_32.S in the Linux
4 * kernel sources (commit 85e2efbb1db9a18d218006706d6e4fbeb0216213, also
5 * known as 2.6.38-rc5). The source file copyrights are as follows:
6 *
7 * (C) Copyright 1995-1996 Gary Thomas (gdt@linuxppc.org)
8 *
9 * Largely rewritten by Cort Dougan (cort@cs.nmt.edu)
10 * and Paul Mackerras.
Kyle Moffett01baa052011-02-23 06:40:38 +000011 */
12
13#include <ppc_asm.tmpl>
14#include <ppc_defs.h>
15#include <config.h>
16
17/*
18 * Extended precision shifts.
19 *
20 * Updated to be valid for shift counts from 0 to 63 inclusive.
21 * -- Gabriel
22 *
23 * R3/R4 has 64 bit value
24 * R5 has shift count
25 * result in R3/R4
26 *
27 * ashrdi3: arithmetic right shift (sign propagation)
28 * lshrdi3: logical right shift
29 * ashldi3: left shift
30 */
31 .globl __lshrdi3
32__lshrdi3:
33 subfic r6,r5,32
34 srw r4,r4,r5 # LSW = count > 31 ? 0 : LSW >> count
35 addi r7,r5,32 # could be xori, or addi with -32
36 slw r6,r3,r6 # t1 = count > 31 ? 0 : MSW << (32-count)
37 srw r7,r3,r7 # t2 = count < 32 ? 0 : MSW >> (count-32)
38 or r4,r4,r6 # LSW |= t1
39 srw r3,r3,r5 # MSW = MSW >> count
40 or r4,r4,r7 # LSW |= t2
41 blr