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1 /* atob: version 4.0
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2 * stream filter to change printable ascii from "btoa" back into 8 bit bytes
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3 * if bad chars, or Csums do not match: exit(1) [and NO output]
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4 *
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5 * Paul Rutter Joe Orost
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6 * philabs!per petsd!joe
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7 */
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8
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9 #include <stdio.h>
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10
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11 #define reg register
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12
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13 #define streq(s0, s1) strcmp(s0, s1) == 0
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14
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15 #define times85(x) ((((((x<<2)+x)<<2)+x)<<2)+x)
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16
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17 long int Ceor = 0;
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18 long int Csum = 0;
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19 long int Crot = 0;
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20 long int word = 0;
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21 long int bcount = 0;
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22
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23 fatal() {
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24 fprintf(stderr, "bad format or Csum to atob\n");
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25 exit(1);
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26 }
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27
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28 #define DE(c) ((c) - '!')
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29
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30 decode(c)
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31 reg c;
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32 {
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33 if (c == 'z') {
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34 if (bcount != 0) {
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35 fatal();
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36 } else {
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37 byteout(0);
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38 byteout(0);
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39 byteout(0);
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40 byteout(0);
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41 }
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42 } else if ((c >= '!') && (c < ('!' + 85))) {
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43 if (bcount == 0) {
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44 word = DE(c);
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45 ++bcount;
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46 } else if (bcount < 4) {
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47 word = times85(word);
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48 word += DE(c);
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49 ++bcount;
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50 } else {
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51 word = times85(word) + DE(c);
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52 byteout((int)((word >> 24) & 255));
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53 byteout((int)((word >> 16) & 255));
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54 byteout((int)((word >> 8) & 255));
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55 byteout((int)(word & 255));
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56 word = 0;
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57 bcount = 0;
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58 }
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59 } else {
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60 fatal();
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61 }
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62 }
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63
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64 FILE *tmp_file;
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65
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66 byteout(c)
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67 reg c;
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68 {
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69 Ceor ^= c;
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70 Csum += c;
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71 Csum += 1;
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72 if ((Crot & 0x80000000)) {
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73 Crot <<= 1;
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74 Crot += 1;
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75 } else {
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76 Crot <<= 1;
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77 }
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78 Crot += c;
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79 putc(c, tmp_file);
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80 }
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81
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82 main(argc, argv)
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83 char **argv;
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84 {
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85 reg c;
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86 reg long int i;
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87 char tmp_name[100];
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88 char buf[100];
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89 long int n1, n2, oeor, osum, orot;
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90
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91 if (argc != 1) {
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92 fprintf(stderr,"bad args to %s\n", argv[0]);
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93 exit(2);
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94 }
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95 sprintf(tmp_name, "/usr/tmp/atob.%x", getpid());
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96 tmp_file = fopen(tmp_name, "w+");
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97 if (tmp_file == NULL) {
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98 fatal();
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99 }
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100 unlink(tmp_name); /* Make file disappear */
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101 /*search for header line*/
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102 for (;;) {
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103 if (fgets(buf, sizeof buf, stdin) == NULL) {
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104 fatal();
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105 }
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106 if (streq(buf, "xbtoa Begin\n")) {
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107 break;
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108 }
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109 }
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110
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111 while ((c = getchar()) != EOF) {
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112 if (c == '\n') {
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113 continue;
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114 } else if (c == 'x') {
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115 break;
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116 } else {
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117 decode(c);
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118 }
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119 }
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120 if(scanf("btoa End N %ld %lx E %lx S %lx R %lx\n",
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121 &n1, &n2, &oeor, &osum, &orot) != 5) {
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122 fatal();
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123 }
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124 if ((n1 != n2) || (oeor != Ceor) || (osum != Csum) || (orot != Crot)) {
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125 fatal();
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126 } else {
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127 /*copy OK tmp file to stdout*/;
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128 fseek(tmp_file, 0L, 0);
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129 for (i = n1; --i >= 0;) {
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130 putchar(getc(tmp_file));
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131 }
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132 }
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133 exit(0);
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134 }
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