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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2006 by Jens Arnold
*
* This program 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 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "config.h"
.section .icode,"ax",@progbits
.global memset16
.type memset16,@function
/* Fills a memory region with specified word value
* Start address must be word aligned, length is in words
* This version is optimized for speed
*
* arguments:
* (4,%sp) - start address
* (8,%sp) - data
* (12,%sp) - length
*
* return value:
* %d0 - start address
*
* register usage:
* %d0 - data (spread to both words when using long stores)
* %d1 - temporary / data (for burst transfer)
* %d2 - data (for burst transfer)
* %d3 - data (for burst transfer)
* %a0 - start address
* %a1 - current address (runs down from end to start)
*
* For maximum speed this routine uses both long stores and burst mode,
* storing whole lines with movem.l. The routine fills memory from end
* to start in order to ease returning the start address.
*/
memset16:
move.l (4,%sp),%a0 /* start address */
move.l (8,%sp),%d0 /* data */
move.l (12,%sp),%a1 /* length */
add.l %a1,%a1
add.l %a0,%a1 /* %a1 = end address */
move.l %a0,%d1
addq.l #6,%d1
and.l #0xFFFFFFFC,%d1 /* %d1 = first long bound + 4 */
cmp.l %d1,%a1 /* at least one aligned longword to fill? */
blo.b .no_longs /* no, jump directly to word loop */
and.l #0xFFFF,%d0 /* start: spread data to both words */
move.l %d0,%d1
swap %d1
or.l %d1,%d0 /* data now in both words */
move.l %a1,%d1
and.l #0xFFFFFFFC,%d1 /* %d1 = last long bound */
cmp.l %d1,%a1 /* one extra word? */
bls.b .end_w1 /* no: skip */
move.w %d0,-(%a1) /* set leading word */
.end_w1:
moveq.l #30,%d1
add.l %a0,%d1
and.l #0xFFFFFFF0,%d1 /* %d1 = first line bound + 16 */
cmp.l %d1,%a1 /* at least one full line to fill? */
blo.b .no_lines /* no, jump to longword loop */
mov.l %a1,%d1
and.l #0xFFFFFFF0,%d1 /* %d1 = last line bound */
cmp.l %d1,%a1 /* any longwords to set? */
bls.b .end_l1 /* no: skip longword loop */
/* leading longword loop: sets 0..3 longwords */
.loop_l1:
move.l %d0,-(%a1) /* store longword */
cmp.l %d1,%a1 /* runs %a1 down to last line bound */
bhi.b .loop_l1
.end_l1:
move.l %d2,-(%sp) /* free some registers */
move.l %d3,-(%sp)
move.l %d0,%d1 /* spread data to 4 data registers */
move.l %d0,%d2
move.l %d0,%d3
lea.l (14,%a0),%a0 /* start address += 14, acct. for trl. data */
/* main loop: set whole lines utilising burst mode */
.loop_line:
lea.l (-16,%a1),%a1 /* pre-decrement */
movem.l %d0-%d3,(%a1) /* store line */
cmp.l %a0,%a1 /* runs %a1 down to first line bound */
bhi.b .loop_line
lea.l (-14,%a0),%a0 /* correct start address */
move.l (%sp)+,%d3 /* restore registers */
move.l (%sp)+,%d2
move.l %a0,%d1 /* %d1 = start address ... */
addq.l #2,%d1 /* ... +2, account for possible trailing word */
cmp.l %d1,%a1 /* any longwords left */
bhi.b .loop_l2 /* yes: jump to longword loop */
bra.b .no_longs /* no: skip loop */
.no_lines:
move.l %a0,%d1 /* %d1 = start address ... */
addq.l #2,%d1 /* ... +2, account for possible trailing word */
/* trailing longword loop */
.loop_l2:
move.l %d0,-(%a1) /* store longword */
cmp.l %d1,%a1 /* runs %a1 down to first long bound */
bhi.b .loop_l2
.no_longs:
cmp.l %a0,%a1 /* any words left? */
bls.b .end_w2 /* no: skip loop */
/* trailing word loop */
.loop_w2:
move.w %d0,-(%a1) /* store word */
cmp.l %a0,%a1 /* runs %a1 down to start address */
bhi.b .loop_w2
.end_w2:
move.l %a0,%d0 /* return start address */
rts
.end:
.size memset16,.end-memset16
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