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23
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1 /*
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2 input.c
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3
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4 Copyright © 2011 William Astle
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5
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6 This file is part of LWTOOLS.
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7
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8 LWTOOLS is free software: you can redistribute it and/or modify it under the
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9 terms of the GNU General Public License as published by the Free Software
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10 Foundation, either version 3 of the License, or (at your option) any later
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11 version.
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12
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13 This program is distributed in the hope that it will be useful, but WITHOUT
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14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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16 more details.
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17
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18 You should have received a copy of the GNU General Public License along with
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19 this program. If not, see <http://www.gnu.org/licenses/>.
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20 */
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21
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22 /*
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23 handle reading input for the rest of the system
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24 */
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25
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26 #include <stdlib.h>
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27 #include <stdio.h>
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28 #include <string.h>
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29
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30 #include <lw_alloc.h>
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31
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32 #define __input_c_seen__
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33 #include "lwbasic.h"
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34
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35 struct input_state
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36 {
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37 FILE *fp;
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38 int error;
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39 };
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40
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41 static void input_init(cstate *state)
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42 {
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43 struct input_state *sp;
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44
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45 sp = lw_alloc(sizeof(struct input_state));
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46 sp -> error = 0;
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47
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48 if (!(state -> input_file) || strcmp(state -> input_file, "-"))
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49 {
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50 sp -> fp = stdin;
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51 }
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52 else
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53 {
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54 sp -> fp = fopen(state -> input_file, "rb");
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55 if (!(sp -> fp))
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56 {
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57 fprintf(stderr, "Cannot open input file\n");
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58 exit(1);
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59 }
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60 }
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61
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62 state -> input_state = sp;
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63 }
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64
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65 int input_getchar(cstate *state)
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66 {
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67 int r;
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68 struct input_state *sp;
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69
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70 if (!(state -> input_state))
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71 input_init(state);
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72 sp = state -> input_state;
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73
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74
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75 if (sp -> error)
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76 return -2;
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77
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78 if (feof(sp -> fp))
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79 return -1;
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80
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81 r = fgetc(sp -> fp);
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82 if (r == EOF)
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83 return -1;
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84 return r;
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85 }
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