busybox

/* vi: set sw=4 ts=4: */

/*

 * Licensed under GPLv2 or later, see file LICENSE in this source tree.

 */

​

#include "libbb.h"

#include <math.h>

​

//usage:#define dc_trivial_usage

//usage:       "EXPRESSION..."

//usage:

//usage:#define dc_full_usage "\n\n"

//usage:       "Tiny RPN calculator. Operations:\n"

//usage:       "+, add, -, sub, *, mul, /, div, %, mod, "IF_FEATURE_DC_LIBM("**, exp, ")"and, or, not, xor,\n"

//usage:       "p - print top of the stack (without popping),\n"

//usage:       "f - print entire stack,\n"

//usage:       "o - pop the value and set output radix (must be 10, 16, 8 or 2).\n"

//usage:       "Examples: 'dc 2 2 add p' -> 4, 'dc 8 8 mul 2 2 + / p' -> 16"

//usage:

//usage:#define dc_example_usage

//usage:       "$ dc 2 2 + p\n"

//usage:       "4\n"

//usage:       "$ dc 8 8 \\* 2 2 + / p\n"

//usage:       "16\n"

//usage:       "$ dc 0 1 and p\n"

//usage:       "0\n"

//usage:       "$ dc 0 1 or p\n"

//usage:       "1\n"

//usage:       "$ echo 72 9 div 8 mul p | dc\n"

//usage:       "64\n"

​

#if 0

typedef unsigned data_t;

#define DATA_FMT ""

#elif 0

typedef unsigned long data_t;

#define DATA_FMT "l"

#else

typedef unsigned long long data_t;

#define DATA_FMT "ll"

#endif

​

​

struct globals {

    unsigned pointer;

    unsigned base;

    double stack[1];

} FIX_ALIASING;

enum { STACK_SIZE = (COMMON_BUFSIZE - offsetof(struct globals, stack)) / sizeof(double) };

#define G (*(struct globals*)&bb_common_bufsiz1)

#define pointer   (G.pointer   )

#define base      (G.base      )

#define stack     (G.stack     )

#define INIT_G() do { \

    base = 10; \

} while (0)

​

​

static void push(double a)

{

    if (pointer >= STACK_SIZE)

        bb_error_msg_and_die("stack overflow");

    stack[pointer++] = a;

}

​

static double pop(void)

{

    if (pointer == 0)

        bb_error_msg_and_die("stack underflow");

    return stack[--pointer];

}

​

static void add(void)

{

    push(pop() + pop());

}

​

static void sub(void)

{

    double subtrahend = pop();

​

    push(pop() - subtrahend);

}

​

static void mul(void)

{

    push(pop() * pop());

}

​

#if ENABLE_FEATURE_DC_LIBM

static void power(void)

{