Update internal.h to conditionally include asm/string.h

[oweals/busybox.git] / math.c

diff --git a/math.c b/math.c
index 75b4cdeb590bc2e66724f2fda140d14d3be94ee1..eb8f331fdb96705bc520eaaad6e9aa69318a2f49 100644 (file)
--- a/math.c
+++ b/math.c
@@ -1,5 +1,6 @@
 /* vi: set sw=4 ts=4: */
 #include "internal.h"
+#include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -7,7 +8,13 @@
 
 /* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */
 
-static const char math_usage[] = "math expression ...";
+static const char math_usage[] = "math expression ...\n"
+#ifndef BB_FEATURE_TRIVIAL_HELP
+               "\nThis is a Tiny RPN calculator that understands the\n"
+               "following operations: +, -, /, *, and, or, not, eor.\n"
+               "i.e. 'math 2 2 add' -> 4, and 'math 8 8 \\* 2 2 + /' -> 16\n"
+#endif
+               ;
 
 static double stack[100];
 static unsigned int pointer;
@@ -85,14 +92,14 @@ struct op {
 };
 
 static const struct op operators[] = {
-       {"add", add},
+       {"+", add},
+       {"-", sub},
+       {"*", mul},
+       {"/", divide},
        {"and", and},
-       {"div", divide},
-       {"eor", eor},
-       {"mul", mul},
-       {"not", not},
        {"or", or},
-       {"sub", sub},
+       {"not", not},
+       {"eor", eor},
        {0, 0}
 };
 
@@ -125,13 +132,59 @@ static void stack_machine(const char *argument)
        exit(-1);
 }
 
+/* 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 math_main(int argc, char **argv)
 {
-       while (argc >= 2) {
-               stack_machine(argv[1]);
-               argv++;
-               argc--;
+       /* 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 = cstring_lineFromFile(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]=='-')
+                       usage(math_usage);
+               while (argc >= 2) {
+                       stack_machine(argv[1]);
+                       argv++;
+                       argc--;
+               }
        }
        stack_machine(0);
-       return 0;
+       return( TRUE);
 }