1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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4 | */
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5 |
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6 | #include "libbb.h"
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7 | #include <math.h>
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8 |
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9 | /* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */
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10 |
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11 | enum { STACK_SIZE = COMMON_BUFSIZE / sizeof(double) };
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12 |
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13 | #define stack ((double*)&bb_common_bufsiz1)
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14 | static unsigned int pointer;
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15 | static unsigned char base;
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16 |
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17 | static void push(double a)
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18 | {
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19 | if (pointer >= STACK_SIZE)
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20 | bb_error_msg_and_die("stack overflow");
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21 | stack[pointer++] = a;
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22 | }
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23 |
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24 | static double pop(void)
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25 | {
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26 | if (pointer == 0)
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27 | bb_error_msg_and_die("stack underflow");
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28 | return stack[--pointer];
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29 | }
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30 |
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31 | static void add(void)
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32 | {
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33 | push(pop() + pop());
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34 | }
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35 |
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36 | static void sub(void)
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37 | {
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38 | double subtrahend = pop();
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39 |
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40 | push(pop() - subtrahend);
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41 | }
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42 |
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43 | static void mul(void)
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44 | {
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45 | push(pop() * pop());
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46 | }
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47 |
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48 | static void power(void)
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49 | {
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50 | double topower = pop();
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51 |
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52 | push(pow(pop(), topower));
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53 | }
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54 |
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55 | static void divide(void)
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56 | {
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57 | double divisor = pop();
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58 |
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59 | push(pop() / divisor);
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60 | }
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61 |
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62 | static void mod(void)
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63 | {
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64 | unsigned int d = pop();
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65 |
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66 | push((unsigned int) pop() % d);
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67 | }
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68 |
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69 | static void and(void)
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70 | {
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71 | push((unsigned int) pop() & (unsigned int) pop());
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72 | }
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73 |
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74 | static void or(void)
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75 | {
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76 | push((unsigned int) pop() | (unsigned int) pop());
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77 | }
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78 |
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79 | static void eor(void)
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80 | {
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81 | push((unsigned int) pop() ^ (unsigned int) pop());
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82 | }
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83 |
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84 | static void not(void)
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85 | {
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86 | push(~(unsigned int) pop());
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87 | }
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88 |
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89 | static void set_output_base(void)
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90 | {
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91 | base = (unsigned char)pop();
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92 | if ((base != 10) && (base != 16)) {
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93 | bb_error_msg("error, base %d is not supported", base);
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94 | base = 10;
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95 | }
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96 | }
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97 |
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98 | static void print_base(double print)
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99 | {
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100 | if (base == 16)
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101 | printf("%x\n", (unsigned int)print);
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102 | else
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103 | printf("%g\n", print);
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104 | }
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105 |
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106 | static void print_stack_no_pop(void)
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107 | {
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108 | unsigned int i = pointer;
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109 | while (i)
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110 | print_base(stack[--i]);
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111 | }
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112 |
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113 | static void print_no_pop(void)
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114 | {
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115 | print_base(stack[pointer-1]);
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116 | }
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117 |
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118 | struct op {
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119 | const char name[4];
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120 | void (*function) (void);
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121 | };
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122 |
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123 | static const struct op operators[] = {
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124 | {"+", add},
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125 | {"add", add},
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126 | {"-", sub},
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127 | {"sub", sub},
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128 | {"*", mul},
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129 | {"mul", mul},
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130 | {"/", divide},
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131 | {"div", divide},
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132 | {"**", power},
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133 | {"exp", power},
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134 | {"pow", power},
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135 | {"%", mod},
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136 | {"mod", mod},
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137 | {"and", and},
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138 | {"or", or},
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139 | {"not", not},
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140 | {"eor", eor},
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141 | {"xor", eor},
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142 | {"p", print_no_pop},
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143 | {"f", print_stack_no_pop},
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144 | {"o", set_output_base},
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145 | {"", 0}
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146 | };
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147 |
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148 | static void stack_machine(const char *argument)
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149 | {
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150 | char *endPointer = 0;
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151 | double d;
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152 | const struct op *o = operators;
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153 |
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154 | if (argument == 0)
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155 | return;
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156 |
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157 | d = strtod(argument, &endPointer);
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158 |
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159 | if (endPointer != argument) {
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160 | push(d);
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161 | return;
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162 | }
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163 |
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164 | while (o->name[0]) {
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165 | if (strcmp(o->name, argument) == 0) {
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166 | o->function();
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167 | return;
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168 | }
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169 | o++;
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170 | }
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171 | bb_error_msg_and_die("%s: syntax error", argument);
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172 | }
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173 |
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174 | /* return pointer to next token in buffer and set *buffer to one char
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175 | * past the end of the above mentioned token
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176 | */
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177 | static char *get_token(char **buffer)
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178 | {
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179 | char *start = NULL;
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180 | char *current;
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181 |
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182 | current = skip_whitespace(*buffer);
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183 | if (*current != 0) {
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184 | start = current;
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185 | current = skip_non_whitespace(current);
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186 | *buffer = current;
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187 | }
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188 | return start;
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189 | }
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190 |
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191 | /* In Perl one might say, scalar m|\s*(\S+)\s*|g */
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192 | static int number_of_tokens(char *buffer)
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193 | {
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194 | int i = 0;
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195 | char *b = buffer;
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196 | while (get_token(&b)) { i++; }
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197 | return i;
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198 | }
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199 |
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200 | int dc_main(int argc, char **argv);
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201 | int dc_main(int argc, char **argv)
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202 | {
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203 | /* take stuff from stdin if no args are given */
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204 | if (argc <= 1) {
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205 | int i, len;
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206 | char *line = NULL;
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207 | char *cursor = NULL;
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208 | char *token = NULL;
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209 | while ((line = xmalloc_getline(stdin))) {
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210 | cursor = line;
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211 | len = number_of_tokens(line);
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212 | for (i = 0; i < len; i++) {
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213 | token = get_token(&cursor);
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214 | *cursor++ = 0;
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215 | stack_machine(token);
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216 | }
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217 | free(line);
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218 | }
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219 | } else {
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220 | if (*argv[1] == '-')
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221 | bb_show_usage();
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222 | while (argc >= 2) {
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223 | stack_machine(argv[1]);
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224 | argv++;
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225 | argc--;
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226 | }
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227 | }
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228 | return EXIT_SUCCESS;
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229 | }
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