mirror of
https://github.com/topjohnwu/ndk-busybox.git
synced 2024-12-05 02:16:49 +00:00
225 lines
3.7 KiB
C
225 lines
3.7 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 tarball for details.
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*/
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#include "libbb.h"
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#include <math.h>
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/* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */
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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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};
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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 { } 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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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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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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unsigned d = pop();
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push((unsigned) pop() % d);
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}
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static void and(void)
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{
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push((unsigned) pop() & (unsigned) pop());
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}
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static void or(void)
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{
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push((unsigned) pop() | (unsigned) pop());
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}
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static void eor(void)
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{
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push((unsigned) pop() ^ (unsigned) pop());
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}
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static void not(void)
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{
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push(~(unsigned) pop());
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}
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static void set_output_base(void)
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{
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base = (unsigned)pop();
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if ((base != 10) && (base != 16)) {
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bb_error_msg("error, base %d is not supported", base);
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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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if (base == 16)
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printf("%x\n", (unsigned)print);
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else
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printf("%g\n", print);
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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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{"**", power},
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{"exp", power},
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{"pow", power},
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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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{ /* zero filled */ }
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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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if (argument == 0)
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return;
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d = strtod(argument, &endPointer);
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if (endPointer != argument) {
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push(d);
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return;
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}
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while (o->name[0]) {
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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("%s: syntax error", 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) 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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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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