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   1 /***************************************************************************
   2  *   Copyright (C) 2010 by Spencer Oliver                                  *
   3  *   spen@spen-soft.co.uk                                                  *
   4  *                                                                         *
   5  *   This program is free software; you can redistribute it and/or modify  *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation; either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   This program is distributed in the hope that it will be useful,       *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15  *   You should have received a copy of the GNU General Public License     *
  16  *   along with this program; if not, write to the                         *
  17  *   Free Software Foundation, Inc.,                                       *
  18  *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.           *
  19  ***************************************************************************/
  20
  21 /*
  22         parameters:
  23         r0 - pointer to struct { uint32_t size_in_result_out, uint32_t addr }
  24         r1 - value to check
  25 */
  26
  27         .text
  28         .syntax unified
  29         .cpu cortex-m0
  30         .thumb
  31         .thumb_func
  32
  33         .align  2
  34
  35 BLOCK_SIZE_RESULT       = 0
  36 BLOCK_ADDRESS           = 4
  37 SIZEOF_STRUCT_BLOCK     = 8
  38
  39 start:
  40 block_loop:
  41         ldr     r2, [r0, #BLOCK_SIZE_RESULT]    /* get size */
  42         tst     r2, r2
  43         beq     done
  44
  45         ldr     r3, [r0, #BLOCK_ADDRESS]        /* get address */
  46
  47 word_loop:
  48         ldr     r4, [r3]        /* read word */
  49         adds    r3, #4
  50
  51         cmp     r4, r1
  52         bne     not_erased
  53
  54         subs    r2, #1
  55         bne     word_loop
  56
  57         movs    r4, #1          /* block is erased */
  58 save_result:
  59         str     r4, [r0, #BLOCK_SIZE_RESULT]
  60         adds    r0, #SIZEOF_STRUCT_BLOCK
  61         b       block_loop
  62
  63 not_erased:
  64         movs    r4, #0
  65         b       save_result
  66
  67 /* Avoid padding at .text segment end. Otherwise exit point check fails. */
  68         .skip   ( . - start + 2) & 2, 0
  69
  70 done:
  71         bkpt    #0
  72
  73         .end