diff options
author | Eric Andersen <andersen@codepoet.org> | 2001-10-24 09:00:29 +0400 |
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committer | Eric Andersen <andersen@codepoet.org> | 2001-10-24 09:00:29 +0400 |
commit | bdfd0d78bc44e73d693510e70087857785b3b521 (patch) | |
tree | 153a573095afac8d8d0ea857759ecabd77fb28b7 /dc.c | |
parent | 9260fc5552a3ee52eb95823aa6689d52a1ffd33c (diff) |
Major rework of the directory structure and the entire build system.
-Erik
Diffstat (limited to 'dc.c')
-rw-r--r-- | dc.c | 182 |
1 files changed, 0 insertions, 182 deletions
@@ -1,182 +0,0 @@ -/* vi: set sw=4 ts=4: */ -#include <ctype.h> -#include <stdio.h> -#include <stdlib.h> -#include <string.h> -#include <unistd.h> -#include <math.h> -#include "busybox.h" - -/* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */ - -static double stack[100]; -static unsigned int pointer; - -static void push(double a) -{ - if (pointer >= (sizeof(stack) / sizeof(*stack))) - error_msg_and_die("stack overflow"); - stack[pointer++] = a; -} - -static double pop() -{ - if (pointer == 0) - error_msg_and_die("stack underflow"); - return stack[--pointer]; -} - -static void add() -{ - push(pop() + pop()); -} - -static void sub() -{ - double subtrahend = pop(); - - push(pop() - subtrahend); -} - -static void mul() -{ - push(pop() * pop()); -} - -static void divide() -{ - double divisor = pop(); - - push(pop() / divisor); -} - -static void and() -{ - push((unsigned int) pop() & (unsigned int) pop()); -} - -static void or() -{ - push((unsigned int) pop() | (unsigned int) pop()); -} - -static void eor() -{ - push((unsigned int) pop() ^ (unsigned int) pop()); -} - -static void not() -{ - push(~(unsigned int) pop()); -} - -static void print() -{ - printf("%g\n", pop()); -} - -struct op { - const char *name; - void (*function) (); -}; - -static const struct op operators[] = { - {"+", add}, - {"add", add}, - {"-", sub}, - {"sub", sub}, - {"*", mul}, - {"mul", mul}, - {"/", divide}, - {"div", divide}, - {"and", and}, - {"or", or}, - {"not", not}, - {"eor", eor}, - {0, 0} -}; - -static void stack_machine(const char *argument) -{ - char *endPointer = 0; - double d; - const struct op *o = operators; - - if (argument == 0) { - print(); - 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++; - } - 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 = get_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]=='-') - show_usage(); - while (argc >= 2) { - stack_machine(argv[1]); - argv++; - argc--; - } - } - stack_machine(0); - return EXIT_SUCCESS; -} |