67 lines
1.4 KiB
C
67 lines
1.4 KiB
C
/*
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* MWC86 CPS Version 3.1.1.
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* Copyright (c) 1982-1986 by Mark Williams Company, Chicago.
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* All rights reserved. May not be copied or disclosed without permission.
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*/
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#include <ctype.h>
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#define ERROR 0x10 /* largest input base */
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/*
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* atod() converts the string 'num' to a double and returns its value.
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* If there is a non-digit in the string, or if there is an overflow,
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* then atod() exits with an appropriate error message.
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* atod() accepts leading zero for octal and leading 0x for hexidecimal;
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* in the latter case, 'a'-'f' and 'A'-'F' are accepted as digits.
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*/
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double
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atod(num)
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char *num;
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{
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register char *str;
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register int i;
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double res = 0,
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base = 10;
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str = num;
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i = *str++;
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if (i == '0')
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if ((i = *str++) == 'x') {
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i = *str++;
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base = 0x10;
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} else
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base = 010;
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for (; i != '\0'; i = *str++) {
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i = todigit(i);
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if (i >= base)
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die("bad number '%s'", num);
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res = res * base + i;
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if (res+1 == res)
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die("number too big '%s'", num);
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}
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return (res);
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}
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/*
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* todigit() converts character 'ch' to an integer equivalent,
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* assuming that 'ch' is a digit or 'a'-'f' or 'A'-'F'.
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* If this is not true, then it returns ERROR.
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*/
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todigit(ch)
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register int ch;
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{
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if (!isascii(ch))
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return (ERROR);
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if (isdigit(ch))
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return (ch - '0' + 0);
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if (isupper(ch))
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ch = tolower(ch);
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if ('a' <= ch && ch <= 'f')
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return (ch - 'a' + 0xA);
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return (ERROR);
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}
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