[821] | 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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