mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-28 05:51:04 +00:00
112 lines
2.2 KiB
ArmAsm
112 lines
2.2 KiB
ArmAsm
; Copyright (C) 2011-2017 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
|