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/***************************************************************************
* Copyright (C) 2014 by Angus Gratton *
* Derived from stm32f1x.S:
* Copyright (C) 2011 by Andreas Fritiofson *
* andreas.fritiofson@gmail.com *
* Copyright (C) 2013 by Roman Dmitrienko *
* me@iamroman.org *
* *
* 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 program 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. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program. If not, see <http://www.gnu.org/licenses/>. *
***************************************************************************/
.text
.syntax unified
.cpu cortex-m0
.thumb
.thumb_func
/* Written for NRF51822 (src/flash/nor/nrf51.c) however the NRF NVMC is
* very generic (CPU blocks during flash writes), so this is actually
* just a generic word-oriented copy routine for cortex-m0 (also
* suitable for cortex m0plus/m3/m4.)
*
* To assemble:
* arm-none-eabi-gcc -c cortex-m0.S
*
* To disassemble:
* arm-none-eabi-objdump -o cortex-m0.o
*
* Thanks to Jens Bauer for providing advice on some of the tweaks.
*/
/* Params:
* r0 - byte count (in)
* r1 - workarea start
* r2 - workarea end
* r3 - target address
* Clobbered:
* r4 - rp
* r5 - wp, tmp
*/
wait_fifo:
ldr r5, [r1, #0] /* read wp */
cmp r5, #0 /* abort if wp == 0 */
beq exit
ldr r4, [r1, #4] /* read rp */
cmp r4, r5 /* wait until rp != wp */
beq wait_fifo
ldmia r4!, {r5} /* "*target_address++ = *rp++" */
stmia r3!, {r5}
cmp r4, r2 /* wrap rp at end of work area buffer */
bcc no_wrap
mov r4, r1
adds r4, #8 /* skip rp,wp at start of work area */
no_wrap:
str r4, [r1, #4] /* write back rp */
subs r0, #4 /* decrement byte count */
bne wait_fifo /* loop if not done */
exit:
bkpt #0
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