Goetz Bock writes:

Dear list,

during my quest do pack busybox into an RPM, I've fixed a small bug
(missing \n) in dc's usage. And added two additional operations: mod and
exp/power.

Feel free to drop them.

2 files changed, 24 insertions, 2 deletions

diff --git a/include/usage.h b/include/usage.h
index 851023ea5..268c23cac 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -280,8 +280,10 @@
         "expression ..."
 #define dc_full_usage \
         "This is a Tiny RPN calculator that understands the\n" \
-        "following operations: +, -, /, *, and, or, not, eor.\n" \
-        "i.e., 'dc 2 2 add' -> 4, and 'dc 8 8 \\* 2 2 + /' -> 16" \
+        "following operations: +, add, -, sub, *, mul, /, div, %, mod, "\
+        "**, exp, and, or, not, eor.\n" \
+        "For example: 'dc 2 2 add' -> 4, and 'dc 8 8 \\* 2 2 + /' -> 16.\n" \
+        "\nOptions:\n" \
         "p - Prints the value on the top of the stack, without altering the stack.\n" \
         "f - Prints the entire contents of the stack without altering anything.\n" \
         "o - Pops the value off the top of the stack and uses it to set the output radix.\n" \
diff --git a/miscutils/dc.c b/miscutils/dc.c
index 451423c62..f574ae4a0 100644
--- a/miscutils/dc.c
+++ b/miscutils/dc.c
@@ -44,6 +44,13 @@ 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();
@@ -51,6 +58,13 @@ static void divide(void)
         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());
@@ -119,10 +133,16 @@ static const struct op operators[] = {
         {"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},