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authorGravatar John Beppu <beppu@lbox.org>2000-06-21 19:06:16 +0000
committerGravatar John Beppu <beppu@lbox.org>2000-06-21 19:06:16 +0000
commit0021679b0dc5767e0c023b28b36eeb1476dc2364 (patch)
tree04ff8031a2151a0f95040bbc4bdf2f616d68a540 /miscutils/dc.c
parentb405dfa54df117201d93dcb7d24e9e9873737da6 (diff)
downloadbusybox-0021679b0dc5767e0c023b28b36eeb1476dc2364.tar.gz
busybox-0021679b0dc5767e0c023b28b36eeb1476dc2364.tar.bz2
+ added dc (aka the function formerly known as math)
+ did all the housekeeping that this change requires.
Diffstat (limited to 'miscutils/dc.c')
-rw-r--r--miscutils/dc.c194
1 files changed, 194 insertions, 0 deletions
diff --git a/miscutils/dc.c b/miscutils/dc.c
new file mode 100644
index 000000000..37c7731d2
--- /dev/null
+++ b/miscutils/dc.c
@@ -0,0 +1,194 @@
+/* vi: set sw=4 ts=4: */
+#include "internal.h"
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <math.h>
+
+/* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */
+
+static const char dc_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;
+
+static void push(double a)
+{
+ if (pointer >= (sizeof(stack) / sizeof(*stack))) {
+ fprintf(stderr, "math: stack overflow\n");
+ exit(-1);
+ } else
+ stack[pointer++] = a;
+}
+
+static double pop()
+{
+ if (pointer == 0) {
+ fprintf(stderr, "math: stack underflow\n");
+ exit(-1);
+ }
+ 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++;
+ }
+ fprintf(stderr, "math: %s: syntax error.\n", 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 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 = 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(dc_usage);
+ while (argc >= 2) {
+ stack_machine(argv[1]);
+ argv++;
+ argc--;
+ }
+ }
+ stack_machine(0);
+ return( TRUE);
+}