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/* vi: set sw=4 ts=4: */
/*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include "libbb.h"
#include <math.h>
/* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */
struct globals {
unsigned pointer;
unsigned base;
double stack[1];
};
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)
{
double topower = pop();
push(pow(pop(), topower));
}
#endif
static void divide(void)
{
double divisor = pop();
push(pop() / divisor);
}
static void mod(void)
{
unsigned d = pop();
push((unsigned) pop() % d);
}
static void and(void)
{
push((unsigned) pop() & (unsigned) pop());
}
static void or(void)
{
push((unsigned) pop() | (unsigned) pop());
}
static void eor(void)
{
push((unsigned) pop() ^ (unsigned) pop());
}
static void not(void)
{
push(~(unsigned) pop());
}
static void set_output_base(void)
{
static const char bases[] ALIGN1 = { 2, 8, 10, 16, 0 };
unsigned b = (unsigned)pop();
base = *strchrnul(bases, b);
if (base == 0) {
bb_error_msg("error, base %u is not supported", b);
base = 10;
}
}
static void print_base(double print)
{
unsigned x, i;
if (base == 10) {
printf("%g\n", print);
return;
}
x = (unsigned)print;
switch (base) {
case 16:
printf("%x\n", x);
break;
case 8:
printf("%o\n", x);
break;
default: /* base 2 */
i = (unsigned)INT_MAX + 1;
do {
if (x & i) break;
i >>= 1;
} while (i > 1);
do {
bb_putchar('1' - !(x & i));
i >>= 1;
} while (i);
bb_putchar('\n');
}
}
static void print_stack_no_pop(void)
{
unsigned i = pointer;
while (i)
print_base(stack[--i]);
}
static void print_no_pop(void)
{
print_base(stack[pointer-1]);
}
struct op {
const char name[4];
void (*function) (void);
};
static const struct op operators[] = {
{"+", add},
{"add", add},
{"-", sub},
{"sub", sub},
{"*", mul},
{"mul", mul},
{"/", divide},
{"div", divide},
#if ENABLE_FEATURE_DC_LIBM
{"**", power},
{"exp", power},
{"pow", power},
#endif
{"%", mod},
{"mod", mod},
{"and", and},
{"or", or},
{"not", not},
{"eor", eor},
{"xor", eor},
{"p", print_no_pop},
{"f", print_stack_no_pop},
{"o", set_output_base},
{ /* zero filled */ }
};
static void stack_machine(const char *argument)
{
char *endPointer;
double d;
const struct op *o = operators;
if (argument == 0)
return;
d = strtod(argument, &endPointer);
if (endPointer != argument) {
push(d);
return;
}
while (o->name[0]) {
if (strcmp(o->name, argument) == 0) {
o->function();
return;
}
o++;
}
bb_error_msg_and_die("%s: syntax error", argument);
}
/* return pointer to next token in buffer and set *buffer to one char
* past the end of the above mentioned token
*/
static char *get_token(char **buffer)
{
char *current = skip_whitespace(*buffer);
if (*current != '\0') {
*buffer = skip_non_whitespace(current);
return current;
}
return NULL;
}
int dc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int dc_main(int argc UNUSED_PARAM, char **argv)
{
INIT_G();
argv++;
if (!argv[0]) {
/* take stuff from stdin if no args are given */
char *line;
char *cursor;
char *token;
while ((line = xmalloc_fgetline(stdin)) != NULL) {
cursor = line;
while (1) {
token = get_token(&cursor);
if (!token) break;
*cursor++ = '\0';
stack_machine(token);
}
free(line);
}
} else {
if (argv[0][0] == '-')
bb_show_usage();
do {
stack_machine(*argv);
} while (*++argv);
}
return EXIT_SUCCESS;
}
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