/* vi: set sw=4 ts=4: */ #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 = *buffer; while (isspace(*current)) { current++; } 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 = bb_get_chomped_line_from_file(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; }