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|
; Copyright (C) 2011-2013 Free Software Foundation, Inc.
; Contributed by Red Hat.
;
; This file is free software; you can redistribute it and/or modify it
; under the terms of the GNU General Public License as published by the
; Free Software Foundation; either version 3, or (at your option) any
; later version.
;
; This file is distributed in the hope that it will be useful, but
; WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
; General Public License for more details.
;
; Under Section 7 of GPL version 3, you are granted additional
; permissions described in the GCC Runtime Library Exception, version
; 3.1, as published by the Free Software Foundation.
;
; You should have received a copy of the GNU General Public License and
; a copy of the GCC Runtime Library Exception along with this program;
; see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
; <http://www.gnu.org/licenses/>.
r8 = 0xffef0
r16 = 0xffee8
r9 = 0xffef1
r17 = 0xffee9
r10 = 0xffef2
r18 = 0xffeea
r11 = 0xffef3
r19 = 0xffeeb
r12 = 0xffef4
r20 = 0xffeec
r13 = 0xffef5
r21 = 0xffeed
r14 = 0xffef6
r22 = 0xffeee
r15 = 0xffef7
r23 = 0xffeef
.text
.global ___lshrsi3
.type ___lshrsi3, @function
___lshrsi3:
;; input:
;;
;; [zero]
;; [count] <= $sp+8
;; [in MSB]
;; [in]
;; [in]
;; [in LSB] <- $sp+4
;; output:
;;
;; [r8..r11] result
;; registers:
;;
;; AX - temp for shift/rotate
;; B - count
mov a, [sp+8] ; A now contains the count
cmp a, #0x20
bc $.Lcount_is_normal
;; count is out of bounds, just return zero.
movw r8, #0
movw r10, #0
ret
.Lcount_is_normal:
cmp0 a
bnz $.Lcount_is_nonzero
;; count is zero, just copy IN to OUT
movw ax, [sp+4]
movw r8, ax
movw ax, [sp+6]
movw r10, ax
ret
.Lcount_is_nonzero:
mov b, a ; B now contains the count also
bf a.4, $.Lcount_lt_16
;; count >= 16, shift 16 at a time.
movw r10, #0
movw ax, [sp+6]
movw r8, ax
mov a, b
and a, #0x0f
sknz
ret
mov b, a ; B now contains the remaining count
inc b
br $.Lloop_top
.Lcount_lt_16:
;; count is nonzero. Do one
movw ax, [sp+6]
shrw ax,1
movw r10, ax
mov a, [sp+5]
rorc a,1
mov r9, a
mov a, [sp+4]
rorc a,1
mov r8, a
;; we did one shift above; do as many more as we need now.
.Lloop_top:
dec b
sknz
ret
movw ax, r10
shrw ax,1
movw r10, ax
mov a, r9
rorc a,1
mov r9, a
mov a, r8
rorc a,1
mov r8, a
br $.Lloop_top
.size ___lshrsi3, .-___lshrsi3
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