1 | /* vi: set sw=4 ts=4: */
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2 | #include "busybox.h"
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3 | #include <ctype.h>
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4 | #include <stdio.h>
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5 | #include <stdlib.h>
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6 | #include <string.h>
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7 | #include <unistd.h>
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8 | #include <math.h>
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9 |
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10 | /* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */
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11 |
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12 | static double stack[100];
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13 | static unsigned int pointer;
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14 | static unsigned char base;
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15 |
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16 | static void push(double a)
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17 | {
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18 | if (pointer >= (sizeof(stack) / sizeof(*stack)))
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19 | bb_error_msg_and_die("stack overflow");
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20 | stack[pointer++] = a;
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21 | }
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22 |
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23 | static double pop(void)
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24 | {
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25 | if (pointer == 0)
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26 | bb_error_msg_and_die("stack underflow");
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27 | return stack[--pointer];
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28 | }
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29 |
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30 | static void add(void)
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31 | {
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32 | push(pop() + pop());
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33 | }
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34 |
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35 | static void sub(void)
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36 | {
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37 | double subtrahend = pop();
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38 |
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39 | push(pop() - subtrahend);
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40 | }
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41 |
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42 | static void mul(void)
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43 | {
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44 | push(pop() * pop());
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45 | }
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46 |
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47 | static void power(void)
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48 | {
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49 | double topower = pop();
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50 |
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51 | push(pow(pop(), topower));
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52 | }
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53 |
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54 | static void divide(void)
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55 | {
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56 | double divisor = pop();
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57 |
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58 | push(pop() / divisor);
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59 | }
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60 |
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61 | static void mod(void)
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62 | {
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63 | unsigned int d = pop();
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64 |
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65 | push((unsigned int) pop() % d);
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66 | }
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67 |
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68 | static void and(void)
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69 | {
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70 | push((unsigned int) pop() & (unsigned int) pop());
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71 | }
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72 |
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73 | static void or(void)
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74 | {
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75 | push((unsigned int) pop() | (unsigned int) pop());
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76 | }
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77 |
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78 | static void eor(void)
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79 | {
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80 | push((unsigned int) pop() ^ (unsigned int) pop());
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81 | }
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82 |
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83 | static void not(void)
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84 | {
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85 | push(~(unsigned int) pop());
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86 | }
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87 |
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88 | static void set_output_base(void)
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89 | {
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90 | base=(unsigned char)pop();
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91 | if ((base != 10) && (base != 16)) {
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92 | fprintf(stderr, "Error: base = %d is not supported.\n", base);
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93 | base=10;
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94 | }
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95 | }
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96 |
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97 | static void print_base(double print)
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98 | {
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99 | if (base == 16)
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100 | printf("%x\n", (unsigned int)print);
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101 | else
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102 | printf("%g\n", print);
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103 | }
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104 |
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105 | static void print_stack_no_pop(void)
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106 | {
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107 | unsigned int i=pointer;
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108 | while (i)
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109 | print_base(stack[--i]);
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110 | }
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111 |
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112 | static void print_no_pop(void)
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113 | {
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114 | print_base(stack[pointer-1]);
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115 | }
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116 |
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117 | struct op {
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118 | const char *name;
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119 | void (*function) (void);
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120 | };
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121 |
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122 | static const struct op operators[] = {
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123 | {"+", add},
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124 | {"add", add},
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125 | {"-", sub},
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126 | {"sub", sub},
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127 | {"*", mul},
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128 | {"mul", mul},
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129 | {"/", divide},
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130 | {"div", divide},
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131 | {"**", power},
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132 | {"exp", power},
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133 | {"pow", power},
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134 | {"%", mod},
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135 | {"mod", mod},
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136 | {"and", and},
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137 | {"or", or},
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138 | {"not", not},
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139 | {"eor", eor},
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140 | {"xor", eor},
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141 | {"p", print_no_pop},
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142 | {"f", print_stack_no_pop},
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143 | {"o", set_output_base},
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144 | {0, 0}
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145 | };
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146 |
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147 | static void stack_machine(const char *argument)
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148 | {
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149 | char *endPointer = 0;
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150 | double d;
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151 | const struct op *o = operators;
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152 |
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153 | if (argument == 0)
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154 | return;
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155 |
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156 | d = strtod(argument, &endPointer);
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157 |
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158 | if (endPointer != argument) {
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159 | push(d);
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160 | return;
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161 | }
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162 |
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163 | while (o->name != 0) {
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164 | if (strcmp(o->name, argument) == 0) {
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165 | (*(o->function)) ();
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166 | return;
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167 | }
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168 | o++;
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169 | }
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170 | bb_error_msg_and_die("%s: syntax error.", argument);
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171 | }
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172 |
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173 | /* return pointer to next token in buffer and set *buffer to one char
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174 | * past the end of the above mentioned token
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175 | */
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176 | static char *get_token(char **buffer)
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177 | {
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178 | char *start = NULL;
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179 | char *current = *buffer;
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180 |
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181 | while (isspace(*current)) { current++; }
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182 | if (*current != 0) {
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183 | start = current;
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184 | while (!isspace(*current) && *current != 0) { current++; }
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185 | *buffer = current;
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186 | }
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187 | return start;
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188 | }
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189 |
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190 | /* In Perl one might say, scalar m|\s*(\S+)\s*|g */
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191 | static int number_of_tokens(char *buffer)
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192 | {
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193 | int i = 0;
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194 | char *b = buffer;
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195 | while (get_token(&b)) { i++; }
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196 | return i;
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197 | }
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198 |
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199 | int dc_main(int argc, char **argv)
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200 | {
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201 | /* take stuff from stdin if no args are given */
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202 | if (argc <= 1) {
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203 | int i, len;
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204 | char *line = NULL;
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205 | char *cursor = NULL;
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206 | char *token = NULL;
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207 | while ((line = bb_get_chomped_line_from_file(stdin))) {
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208 | cursor = line;
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209 | len = number_of_tokens(line);
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210 | for (i = 0; i < len; i++) {
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211 | token = get_token(&cursor);
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212 | *cursor++ = 0;
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213 | stack_machine(token);
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214 | }
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215 | free(line);
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216 | }
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217 | } else {
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218 | if (*argv[1]=='-')
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219 | bb_show_usage();
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220 | while (argc >= 2) {
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221 | stack_machine(argv[1]);
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222 | argv++;
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223 | argc--;
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224 | }
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225 | }
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226 | return EXIT_SUCCESS;
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227 | }
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