Implement a better num2str()
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/lib/num2str.c b/lib/num2str.c
new file mode 100644
index 0000000..e114cdf
--- /dev/null
+++ b/lib/num2str.c
@@ -0,0 +1,48 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+/*
+ * Cheesy number->string conversion, complete with carry rounding error.
+ */
+char *num2str(unsigned long num, int maxlen, int base, int pow2)
+{
+ char postfix[] = { ' ', 'K', 'M', 'G', 'P', 'E' };
+ unsigned int thousand[] = { 1000, 1024 };
+ unsigned int modulo, decimals;
+ int post_index;
+ char tmp[32], fmt[8];
+ char *buf;
+
+ buf = malloc(128);
+
+ for (post_index = 0; base > 1; post_index++)
+ base /= thousand[!!pow2];
+
+ modulo = -1U;
+ while (post_index < sizeof(postfix)) {
+ sprintf(tmp, "%lu", num);
+ if (strlen(tmp) <= maxlen)
+ break;
+
+ modulo = num % thousand[!!pow2];
+ num /= thousand[!!pow2];
+ post_index++;
+ }
+
+ if (modulo == -1U) {
+done:
+ sprintf(buf, "%lu%c", num, postfix[post_index]);
+ return buf;
+ }
+
+ sprintf(tmp, "%lu", num);
+ decimals = maxlen - strlen(tmp);
+ if (decimals <= 1)
+ goto done;
+
+ sprintf(fmt, "%%.%uu", decimals - 1);
+ sprintf(tmp, fmt, modulo);
+ sprintf(buf, "%lu.%s%c", num, tmp, postfix[post_index]);
+ return buf;
+}