54 lines
971 B
C
54 lines
971 B
C
///////////////////////////////////////////////////////////////////////////////
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//
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/// \file hex2bin.c
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/// \brief Converts hexadecimal input strings to binary
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//
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// Author: Lasse Collin
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//
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// This file has been put into the public domain.
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// You can do whatever you want with this file.
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//
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///////////////////////////////////////////////////////////////////////////////
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#include "sysdefs.h"
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#include <stdio.h>
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#include <ctype.h>
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static int
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getbin(int x)
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{
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if (x >= '0' && x <= '9')
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return x - '0';
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if (x >= 'A' && x <= 'F')
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return x - 'A' + 10;
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return x - 'a' + 10;
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}
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int
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main(void)
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{
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while (true) {
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int byte = getchar();
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if (byte == EOF)
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return 0;
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if (!isxdigit(byte))
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continue;
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const int digit = getchar();
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if (digit == EOF || !isxdigit(digit)) {
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fprintf(stderr, "Invalid input\n");
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return 1;
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}
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byte = (getbin(byte) << 4) | getbin(digit);
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if (putchar(byte) == EOF) {
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perror(NULL);
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return 1;
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}
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}
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}
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