| /* vi: set sw=4 ts=4: */ |
| /* |
| * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
| */ |
| |
| #include "busybox.h" |
| #include <ctype.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <unistd.h> |
| #include <math.h> |
| |
| /* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */ |
| |
| static double stack[100]; |
| static unsigned int pointer; |
| static unsigned char base; |
| |
| static void push(double a) |
| { |
| if (pointer >= (sizeof(stack) / sizeof(*stack))) |
| 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()); |
| } |
| |
| static void power(void) |
| { |
| double topower = pop(); |
| |
| push(pow(pop(), topower)); |
| } |
| |
| static void divide(void) |
| { |
| double divisor = pop(); |
| |
| push(pop() / divisor); |
| } |
| |
| static void mod(void) |
| { |
| unsigned int d = pop(); |
| |
| push((unsigned int) pop() % d); |
| } |
| |
| static void and(void) |
| { |
| push((unsigned int) pop() & (unsigned int) pop()); |
| } |
| |
| static void or(void) |
| { |
| push((unsigned int) pop() | (unsigned int) pop()); |
| } |
| |
| static void eor(void) |
| { |
| push((unsigned int) pop() ^ (unsigned int) pop()); |
| } |
| |
| static void not(void) |
| { |
| push(~(unsigned int) pop()); |
| } |
| |
| static void set_output_base(void) |
| { |
| base=(unsigned char)pop(); |
| if ((base != 10) && (base != 16)) { |
| fprintf(stderr, "Error: base = %d is not supported.\n", base); |
| base=10; |
| } |
| } |
| |
| static void print_base(double print) |
| { |
| if (base == 16) |
| printf("%x\n", (unsigned int)print); |
| else |
| printf("%g\n", print); |
| } |
| |
| static void print_stack_no_pop(void) |
| { |
| unsigned int i=pointer; |
| while (i) |
| print_base(stack[--i]); |
| } |
| |
| static void print_no_pop(void) |
| { |
| print_base(stack[pointer-1]); |
| } |
| |
| struct op { |
| const char *name; |
| void (*function) (void); |
| }; |
| |
| static const struct op operators[] = { |
| {"+", add}, |
| {"add", add}, |
| {"-", sub}, |
| {"sub", sub}, |
| {"*", mul}, |
| {"mul", mul}, |
| {"/", divide}, |
| {"div", divide}, |
| {"**", power}, |
| {"exp", power}, |
| {"pow", power}, |
| {"%", 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}, |
| {0, 0} |
| }; |
| |
| static void stack_machine(const char *argument) |
| { |
| char *endPointer = 0; |
| 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 *start = NULL; |
| char *current; |
| |
| current = skip_whitespace(*buffer); |
| if (*current != 0) { |
| start = current; |
| while (!isspace(*current) && *current != 0) { current++; } |
| *buffer = current; |
| } |
| return start; |
| } |
| |
| /* In Perl one might say, scalar m|\s*(\S+)\s*|g */ |
| static int number_of_tokens(char *buffer) |
| { |
| int i = 0; |
| char *b = buffer; |
| while (get_token(&b)) { i++; } |
| return i; |
| } |
| |
| int dc_main(int argc, char **argv) |
| { |
| /* take stuff from stdin if no args are given */ |
| if (argc <= 1) { |
| int i, len; |
| char *line = NULL; |
| char *cursor = NULL; |
| char *token = NULL; |
| while ((line = xmalloc_getline(stdin))) { |
| cursor = line; |
| len = number_of_tokens(line); |
| for (i = 0; i < len; i++) { |
| token = get_token(&cursor); |
| *cursor++ = 0; |
| stack_machine(token); |
| } |
| free(line); |
| } |
| } else { |
| if (*argv[1]=='-') |
| bb_show_usage(); |
| while (argc >= 2) { |
| stack_machine(argv[1]); |
| argv++; |
| argc--; |
| } |
| } |
| return EXIT_SUCCESS; |
| } |