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- ; Copyright (C) 2011-2022 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/>.
- #include "vregs.h"
-
- START_FUNC ___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
- END_FUNC ___lshrsi3
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