Implement a better num2str()

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/lib/num2str.c b/lib/num2str.c
new file mode 100644
index 00000000..e114cdf8
--- /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;
+}