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100 lines
2.5 KiB
C
100 lines
2.5 KiB
C
/***************************************************************************
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* https://github.com/dhylands/projects/blob/master/lpc/lpc-vector-checksum/lpc-vector-checksum.c
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*
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* Copyright (c) 2012 by Dave Hylands
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* All Rights Reserved
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*
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* Permission is granted to any individual or institution to use, copy,
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* modify, or redistribute this file so long as it is not sold for profit,
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* and that this copyright notice is retained.
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*
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***************************************************************************
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*
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* This program calculates the vector checksum used in LPC17xx binary
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* images.
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*
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* Usage: lpc-vector-checksum file
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*
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***************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <errno.h>
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#include <string.h>
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/***************************************************************************/
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/**
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* update_vector_checksum
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*
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* The algorithim is to write the checksum such that the checksum of the
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* first 8 words is equal to zero.
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*
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* The LPC1768 uses little-endian, and this particular routine assumes
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* that it's running on a little-endian architecture.
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*/
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static int update_vector_checksum( const char *filename )
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{
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uint32_t sum;
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uint32_t header[8];
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FILE *fs;
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int i;
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if (( fs = fopen( filename, "r+b" )) == NULL )
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{
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fprintf( stderr, "Unable to open '%s' for reading/writing (%d): %s\n",
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filename, errno, strerror( errno ));
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return 0;
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}
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if ( fread( header, sizeof( header ), 1, fs ) != 1 )
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{
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fprintf( stderr, "Failed to read header from '%s' (perhaps the file is too small?)",
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filename );
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fclose( fs );
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return 0;
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}
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sum = 0;
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for ( i = 0; i < 7; i++ )
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{
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sum += header[i];
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}
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printf( "sum = 0x%08x, value to write = 0x%08x\n", sum, -sum );
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/* write back the checksum to location 7
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* http://sigalrm.blogspot.jp/2011/10/cortex-m3-exception-vector-checksum.html
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*/
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fseek(fs, 0x1c, SEEK_SET);
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sum = -sum;
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fwrite(&sum, 4, 1, fs);
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fclose( fs );
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return 1;
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}
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/***************************************************************************/
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/**
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* main
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*/
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int main( int argc, char **argv )
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{
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int arg;
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if ( argc < 2)
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{
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fprintf( stderr, "Usage: lpc-vector-checksum file ...\n" );
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exit( 1 );
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}
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for ( arg = 1; arg < argc; arg++ )
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{
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update_vector_checksum( argv[ arg ]);
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}
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exit( 0 );
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return 0;
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}
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