1 files changed, 256 insertions, 0 deletions
diff --git a/miscutils/dc.c b/miscutils/dc.c
new file mode 100644
index 0000000..ff2bc3b
--- /dev/null
+++ b/miscutils/dc.c
@@ -0,0 +1,256 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+
+#include "libbb.h"
+#include <math.h>
+
+/* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */
+
+
+struct globals {
+	unsigned pointer;
+	unsigned base;
+	double stack[1];
+};
+enum { STACK_SIZE = (COMMON_BUFSIZE - offsetof(struct globals, stack)) / sizeof(double) };
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define pointer   (G.pointer   )
+#define base      (G.base      )
+#define stack     (G.stack     )
+#define INIT_G() do { \
+	base = 10; \
+} while (0)
+
+
+static void push(double a)
+{
+	if (pointer >= STACK_SIZE)
+		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());
+}
+
+#if ENABLE_FEATURE_DC_LIBM
+static void power(void)
+{
+	double topower = pop();
+
+	push(pow(pop(), topower));
+}
+#endif
+
+static void divide(void)
+{
+	double divisor = pop();
+
+	push(pop() / divisor);
+}
+
+static void mod(void)
+{
+	unsigned d = pop();
+
+	push((unsigned) pop() % d);
+}
+
+static void and(void)
+{
+	push((unsigned) pop() & (unsigned) pop());
+}
+
+static void or(void)
+{
+	push((unsigned) pop() | (unsigned) pop());
+}
+
+static void eor(void)
+{
+	push((unsigned) pop() ^ (unsigned) pop());
+}
+
+static void not(void)
+{
+	push(~(unsigned) pop());
+}
+
+static void set_output_base(void)
+{
+	static const char bases[] ALIGN1 = { 2, 8, 10, 16, 0 };
+	unsigned b = (unsigned)pop();
+
+	base = *strchrnul(bases, b);
+	if (base == 0) {
+		bb_error_msg("error, base %u is not supported", b);
+		base = 10;
+	}
+}
+
+static void print_base(double print)
+{
+	unsigned x, i;
+
+	if (base == 10) {
+		printf("%g\n", print);
+		return;
+	}
+
+	x = (unsigned)print;
+	switch (base) {
+	case 16:
+		printf("%x\n", x);
+		break;
+	case 8:
+		printf("%o\n", x);
+		break;
+	default: /* base 2 */
+		i = (unsigned)INT_MAX + 1;
+		do {
+			if (x & i) break;
+			i >>= 1;
+		} while (i > 1);
+		do {
+			bb_putchar('1' - !(x & i));
+			i >>= 1;
+		} while (i);
+		bb_putchar('\n');
+	}
+}
+
+static void print_stack_no_pop(void)
+{
+	unsigned i = pointer;
+	while (i)
+		print_base(stack[--i]);
+}
+
+static void print_no_pop(void)
+{
+	print_base(stack[pointer-1]);
+}
+
+struct op {
+	const char name[4];
+	void (*function) (void);
+};
+
+static const struct op operators[] = {
+	{"+",   add},
+	{"add", add},
+	{"-",   sub},
+	{"sub", sub},
+	{"*",   mul},
+	{"mul", mul},
+	{"/",   divide},
+	{"div", divide},
+#if ENABLE_FEATURE_DC_LIBM
+	{"**",  power},
+	{"exp", power},
+	{"pow", power},
+#endif
+	{"%",   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},
+	{ /* zero filled */ }
+};
+
+static void stack_machine(const char *argument)
+{
+	char *endPointer;
+	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 *current = skip_whitespace(*buffer);
+	if (*current != '\0') {
+		*buffer = skip_non_whitespace(current);
+		return current;
+	}
+	return NULL;
+}
+
+int dc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int dc_main(int argc UNUSED_PARAM, char **argv)
+{
+	INIT_G();
+
+	argv++;
+	if (!argv[0]) {
+		/* take stuff from stdin if no args are given */
+		char *line;
+		char *cursor;
+		char *token;
+		while ((line = xmalloc_fgetline(stdin)) != NULL) {
+			cursor = line;
+			while (1) {
+				token = get_token(&cursor);
+				if (!token) break;
+				*cursor++ = '\0';
+				stack_machine(token);
+			}
+			free(line);
+		}
+	} else {
+		if (argv[0][0] == '-')
+			bb_show_usage();
+		do {
+			stack_machine(*argv);
+		} while (*++argv);
+	}
+	return EXIT_SUCCESS;
+}