dc: support for bases 2 and 8, by Nate Case (ncase AT xes-inc.com)

function                                             old     new   delta
print_base                                            87     176     +89
set_output_base                                       81      95     +14
static.bases                                           -       5      +5
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/0 up/down: 108/0)             Total: 108 bytes

1 files changed, 32 insertions, 6 deletions

diff --git a/miscutils/dc.c b/miscutils/dc.c
index 7d5886eb2..6d4efa943 100644
--- a/miscutils/dc.c
+++ b/miscutils/dc.c
@@ -98,19 +98,45 @@ static void not(void)
 
 static void set_output_base(void)
 {
-        base = (unsigned)pop();
-        if ((base != 10) && (base != 16)) {
-                bb_error_msg("error, base %d is not supported", base);
+        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)
 {
-        if (base == 16)
-                printf("%x\n", (unsigned)print);
-        else
+        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)