From: Gerhard Sittig <redacted>
Date: Thu, 21 Dec 2023 20:20:55 +0000 (+0100)
Subject: strutil: support special case in power of two calculation
X-Git-Url: http://sigrok.org/gitweb/?p=libsigrok.git;a=commitdiff_plain;h=c3ada48afce7626a980c89e66d592a4242362c57

strutil: support special case in power of two calculation

The sr_next_power_of_two() helper routine rejected input value 0
(an index), considered this case invalid. It is not, requires 1 bit
to hold the value. Return a "power of two" value of 1 for that input,
callers expect that result.
---

diff --git a/src/strutil.c b/src/strutil.c
index 841a682a..2136bd49 100644
--- a/src/strutil.c
+++ b/src/strutil.c
@@ -1844,8 +1844,18 @@ SR_API int sr_next_power_of_two(size_t value, size_t *bits, size_t *power)
 	if (power)
 		*power = 0;
 
-	if (!value)
-		return SR_ERR_ARG;
+	/*
+	 * Handle the special case of input value 0 (needs 1 bit
+	 * and results in "power of two" value 1) here. It is not
+	 * covered by the generic logic below.
+	 */
+	if (!value) {
+		if (bits)
+			*bits = 1;
+		if (power)
+			*power = 1;
+		return SR_OK;
+	}
 
 	need_bits = 0;
 	check_mask = 0;