Last change
on this file since 7bf3856 was 3ae31e9, checked in by Thomas Lopatic <thomas@…>, 7 years ago |
Imported original source code.
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File size:
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1 | /*
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2 | =============================================================================
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3 | strtol.c -- convert a string of ASCII digits to a long
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4 | Version 1 -- 1987-06-12
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5 | =============================================================================
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6 | */
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7 |
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8 | #include "ctype.h"
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9 |
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10 | #define DIGIT(x) (isdigit(x) ? (x)-'0' : islower(x) ? (x)+10-'a' : (x)+10-'A')
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11 |
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12 | #define MBASE ('z' - 'a' + 1 + 10)
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13 |
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14 | long
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15 | strtol(str, ptr, base)
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16 | register char *str;
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17 | char **ptr;
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18 | register int base;
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19 | {
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20 | register long val;
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21 | register int c;
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22 | int xx, neg = 0;
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23 |
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24 | if (ptr != (char **)0)
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25 | *ptr = str; /* in case no number is formed */
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26 |
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27 | if (base < 0 || base > MBASE)
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28 | return (0); /* base is invalid -- should be a fatal error */
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29 |
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30 | if (!isalnum(c = *str)) {
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31 |
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32 | while (isspace(c))
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33 | c = *++str;
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34 |
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35 | switch (c) {
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36 |
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37 | case '-':
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38 | neg++;
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39 |
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40 | case '+': /* fall-through */
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41 | c = *++str;
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42 | }
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43 | }
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44 |
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45 | if (base == 0)
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46 | if (c != '0')
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47 | base = 10;
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48 | else if (str[1] == 'x' || str[1] == 'X')
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49 | base = 16;
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50 | else
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51 | base = 8;
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52 | /*
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53 | for any base > 10, the digits incrementally following
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54 | 9 are assumed to be "abc...z" or "ABC...Z"
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55 | */
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56 |
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57 | if (!isalnum(c) || (xx = DIGIT(c)) >= base)
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58 | return (0); /* no number formed */
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59 |
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60 | if (base == 16 && c == '0' && isxdigit(str[2]) &&
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61 | (str[1] == 'x' || str[1] == 'X'))
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62 | c = *(str += 2); /* skip over leading "0x" or "0X" */
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63 |
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64 | for (val = -DIGIT(c); isalnum(c = *++str) && (xx = DIGIT(c)) < base; )
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65 | /* accumulate neg avoids surprises near MAXLONG */
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66 | val = base * val - xx;
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67 |
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68 | if (ptr != (char **)0)
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69 | *ptr = str;
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70 |
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71 | return (neg ? val : -val);
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72 | }
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