smart_ulltoa5: make available in libbb

git-svn-id: svn://busybox.net/trunk/busybox@16510 69ca8d6d-28ef-0310-b511-8ec308f3f277

1 files changed, 54 insertions, 6 deletions

diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index c72265003..352515af4 100644
--- a/libbb/xfuncs.c
+++ b/libbb/xfuncs.c
@@ -201,23 +201,71 @@ void xsetenv(const char *key, const char *value)
                 bb_error_msg_and_die(bb_msg_memory_exhausted);
 }
 
+
+// Converts unsigned long long value into compact 4-char
+// representation. Examples: "1234", "1.2k", " 27M", "123T"
+// Fifth char is always '\0'
+void smart_ulltoa5(unsigned long long ul, char buf[5])
+{
+        char *fmt;
+        char c;
+        unsigned v,idx = 0;
+        ul *= 10;
+        if (ul > 9999*10) { // do not scale if 9999 or less
+                while (ul >= 10000) {
+                        ul /= 1024;
+                        idx++;
+                }
+        }
+        v = ul; // ullong divisions are expensive, avoid them
+
+        fmt = " 123456789";
+        if (!idx) {             // 9999 or less: use 1234 format
+                c = buf[0] = " 123456789"[v/10000];
+                if (c!=' ') fmt = "0123456789";
+                c = buf[1] = fmt[v/1000%10];
+                if (c!=' ') fmt = "0123456789";
+                buf[2] = fmt[v/100%10];
+                buf[3] = "0123456789"[v/10%10];
+        } else {
+                if (v>=10*10) { // scaled value is >=10: use 123M format
+                        c = buf[0] = " 123456789"[v/1000];
+                        if (c!=' ') fmt = "0123456789";
+                        buf[1] = fmt[v/100%10];
+                        buf[2] = "0123456789"[v/10%10];
+                } else {        // scaled value is <10: use 1.2M format
+                        buf[0] = "0123456789"[v/10];
+                        buf[1] = '.';
+                        buf[2] = "0123456789"[v%10];
+                }
+                // see http://en.wikipedia.org/wiki/Tera
+                buf[3] = " kMGTPEZY"[idx];
+        }
+        buf[4] = '\0';
+}
+
+
 // Convert unsigned integer to ascii, writing into supplied buffer.  A
 // truncated result is always null terminated (unless buflen is 0), and
 // contains the first few digits of the result ala strncpy.
+void BUG_sizeof_unsigned_not_4(void);
 void utoa_to_buf(unsigned n, char *buf, unsigned buflen)
 {
-        int i, out = 0;
+        unsigned i, out, res;
+        if (sizeof(unsigned) != 4)
+                BUG_sizeof_unsigned_not_4();
         if (buflen) {
-                for (i=1000000000; i; i/=10) {
-                        int res = n/i;
-
-                        if ((res || out || i == 1) && --buflen>0) {
+                out = 0;
+                for (i = 1000000000; i; i /= 10) {
+                        res = n / i;
+                        if (res || out || i == 1) {
+                                if (!--buflen) break;
                                 out++;
                                 n -= res*i;
                                 *buf++ = '0' + res;
                         }
                 }
-                *buf = 0;
+                *buf = '\0';
         }
 }