112 lines
2.2 KiB
ArmAsm
112 lines
2.2 KiB
ArmAsm
; Copyright (C) 2011-2017 Free Software Foundation, Inc.
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; Contributed by Red Hat.
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;
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; This file is free software; you can redistribute it and/or modify it
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; under the terms of the GNU General Public License as published by the
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; Free Software Foundation; either version 3, or (at your option) any
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; later version.
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;
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; This file is distributed in the hope that it will be useful, but
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; WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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; General Public License for more details.
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;
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; Under Section 7 of GPL version 3, you are granted additional
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; permissions described in the GCC Runtime Library Exception, version
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; 3.1, as published by the Free Software Foundation.
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;
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; You should have received a copy of the GNU General Public License and
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; a copy of the GCC Runtime Library Exception along with this program;
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; see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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; <http://www.gnu.org/licenses/>.
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#include "vregs.h"
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START_FUNC ___lshrsi3
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;; input:
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;;
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;; [zero]
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;; [count] <= $sp+8
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;; [in MSB]
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;; [in]
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;; [in]
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;; [in LSB] <- $sp+4
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;; output:
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;;
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;; [r8..r11] result
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;; registers:
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;;
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;; AX - temp for shift/rotate
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;; B - count
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mov a, [sp+8] ; A now contains the count
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cmp a, #0x20
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bc $.Lcount_is_normal
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;; count is out of bounds, just return zero.
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movw r8, #0
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movw r10, #0
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ret
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.Lcount_is_normal:
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cmp0 a
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bnz $.Lcount_is_nonzero
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;; count is zero, just copy IN to OUT
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movw ax, [sp+4]
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movw r8, ax
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movw ax, [sp+6]
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movw r10, ax
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ret
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.Lcount_is_nonzero:
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mov b, a ; B now contains the count also
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bf a.4, $.Lcount_lt_16
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;; count >= 16, shift 16 at a time.
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movw r10, #0
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movw ax, [sp+6]
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movw r8, ax
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mov a, b
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and a, #0x0f
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sknz
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ret
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mov b, a ; B now contains the remaining count
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inc b
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br $.Lloop_top
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.Lcount_lt_16:
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;; count is nonzero. Do one
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movw ax, [sp+6]
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shrw ax,1
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movw r10, ax
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mov a, [sp+5]
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rorc a,1
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mov r9, a
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mov a, [sp+4]
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rorc a,1
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mov r8, a
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;; we did one shift above; do as many more as we need now.
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.Lloop_top:
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dec b
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sknz
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ret
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movw ax, r10
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shrw ax,1
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movw r10, ax
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mov a, r9
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rorc a,1
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mov r9, a
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mov a, r8
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rorc a,1
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mov r8, a
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br $.Lloop_top
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END_FUNC ___lshrsi3
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