mirror of
https://github.com/sheumann/hush.git
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293 lines
5.3 KiB
C
293 lines
5.3 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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#include "libbb.h"
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#include <math.h>
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//usage:#define dc_trivial_usage
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//usage: "EXPRESSION..."
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//usage:
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//usage:#define dc_full_usage "\n\n"
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//usage: "Tiny RPN calculator. Operations:\n"
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//usage: "+, add, -, sub, *, mul, /, div, %, mod, "IF_FEATURE_DC_LIBM("**, exp, ")"and, or, not, eor,\n"
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//usage: "p - print top of the stack (without popping),\n"
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//usage: "f - print entire stack,\n"
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//usage: "o - pop the value and set output radix (must be 10, 16, 8 or 2).\n"
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//usage: "Examples: 'dc 2 2 add' -> 4, 'dc 8 8 * 2 2 + /' -> 16"
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//usage:
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//usage:#define dc_example_usage
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//usage: "$ dc 2 2 + p\n"
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//usage: "4\n"
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//usage: "$ dc 8 8 \\* 2 2 + / p\n"
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//usage: "16\n"
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//usage: "$ dc 0 1 and p\n"
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//usage: "0\n"
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//usage: "$ dc 0 1 or p\n"
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//usage: "1\n"
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//usage: "$ echo 72 9 div 8 mul p | dc\n"
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//usage: "64\n"
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#if 0
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typedef unsigned data_t;
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#define DATA_FMT ""
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#elif 0
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typedef unsigned long data_t;
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#define DATA_FMT "l"
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#else
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typedef unsigned long long data_t;
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#define DATA_FMT "ll"
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#endif
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struct globals {
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unsigned pointer;
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unsigned base;
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double stack[1];
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} FIX_ALIASING;
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enum { STACK_SIZE = (COMMON_BUFSIZE - offsetof(struct globals, stack)) / sizeof(double) };
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#define G (*(struct globals*)&bb_common_bufsiz1)
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#define pointer (G.pointer )
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#define base (G.base )
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#define stack (G.stack )
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#define INIT_G() do { \
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base = 10; \
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} while (0)
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static void push(double a)
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{
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if (pointer >= STACK_SIZE)
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bb_error_msg_and_die("stack overflow");
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stack[pointer++] = a;
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}
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static double pop(void)
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{
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if (pointer == 0)
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bb_error_msg_and_die("stack underflow");
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return stack[--pointer];
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}
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static void add(void)
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{
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push(pop() + pop());
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}
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static void sub(void)
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{
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double subtrahend = pop();
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push(pop() - subtrahend);
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}
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static void mul(void)
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{
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push(pop() * pop());
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}
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#if ENABLE_FEATURE_DC_LIBM
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static void power(void)
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{
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double topower = pop();
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push(pow(pop(), topower));
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}
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#endif
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static void divide(void)
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{
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double divisor = pop();
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push(pop() / divisor);
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}
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static void mod(void)
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{
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data_t d = pop();
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push((data_t) pop() % d);
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}
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static void and(void)
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{
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push((data_t) pop() & (data_t) pop());
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}
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static void or(void)
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{
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push((data_t) pop() | (data_t) pop());
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}
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static void eor(void)
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{
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push((data_t) pop() ^ (data_t) pop());
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}
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static void not(void)
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{
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push(~(data_t) pop());
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}
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static void set_output_base(void)
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{
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static const char bases[] ALIGN1 = { 2, 8, 10, 16, 0 };
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unsigned b = (unsigned)pop();
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base = *strchrnul(bases, b);
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if (base == 0) {
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bb_error_msg("error, base %u is not supported", b);
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base = 10;
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}
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}
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static void print_base(double print)
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{
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data_t x, i;
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x = (data_t) print;
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if (base == 10) {
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if (x == print) /* exactly representable as unsigned integer */
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printf("%"DATA_FMT"u\n", x);
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else
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printf("%g\n", print);
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return;
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}
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switch (base) {
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case 16:
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printf("%"DATA_FMT"x\n", x);
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break;
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case 8:
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printf("%"DATA_FMT"o\n", x);
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break;
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default: /* base 2 */
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i = MAXINT(data_t) - (MAXINT(data_t) >> 1);
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/* i is 100000...00000 */
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do {
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if (x & i)
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break;
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i >>= 1;
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} while (i > 1);
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do {
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bb_putchar('1' - !(x & i));
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i >>= 1;
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} while (i);
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bb_putchar('\n');
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}
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}
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static void print_stack_no_pop(void)
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{
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unsigned i = pointer;
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while (i)
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print_base(stack[--i]);
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}
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static void print_no_pop(void)
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{
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print_base(stack[pointer-1]);
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}
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struct op {
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const char name[4];
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void (*function) (void);
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};
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static const struct op operators[] = {
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{"+", add},
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{"add", add},
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{"-", sub},
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{"sub", sub},
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{"*", mul},
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{"mul", mul},
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{"/", divide},
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{"div", divide},
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#if ENABLE_FEATURE_DC_LIBM
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{"**", power},
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{"exp", power},
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{"pow", power},
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#endif
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{"%", mod},
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{"mod", mod},
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{"and", and},
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{"or", or},
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{"not", not},
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{"eor", eor},
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{"xor", eor},
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{"p", print_no_pop},
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{"f", print_stack_no_pop},
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{"o", set_output_base},
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{ "", NULL }
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};
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static void stack_machine(const char *argument)
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{
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char *endPointer;
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double d;
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const struct op *o = operators;
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d = strtod(argument, &endPointer);
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if (endPointer != argument && *endPointer == '\0') {
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push(d);
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return;
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}
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while (o->function) {
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if (strcmp(o->name, argument) == 0) {
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o->function();
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return;
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}
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o++;
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}
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bb_error_msg_and_die("syntax error at '%s'", argument);
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}
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/* return pointer to next token in buffer and set *buffer to one char
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* past the end of the above mentioned token
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*/
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static char *get_token(char **buffer)
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{
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char *current = skip_whitespace(*buffer);
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if (*current != '\0') {
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*buffer = skip_non_whitespace(current);
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return current;
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}
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return NULL;
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}
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int dc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int dc_main(int argc UNUSED_PARAM, char **argv)
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{
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INIT_G();
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argv++;
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if (!argv[0]) {
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/* take stuff from stdin if no args are given */
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char *line;
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char *cursor;
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char *token;
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while ((line = xmalloc_fgetline(stdin)) != NULL) {
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cursor = line;
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while (1) {
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token = get_token(&cursor);
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if (!token)
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break;
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*cursor++ = '\0';
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stack_machine(token);
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}
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free(line);
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}
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} else {
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// why? it breaks "dc -2 2 * p"
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//if (argv[0][0] == '-')
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// bb_show_usage();
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do {
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stack_machine(*argv);
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} while (*++argv);
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}
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return EXIT_SUCCESS;
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}
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