man: add manpage for dna4_revcomp

man/dna4_revcomp.3

@@ -0,0 +1,37 @@
+.TH DNA4_REVCOMP 3 2019-08-12 "LIBDNA" "LIBDNA"
+
+.SH NAME
+dna4_revcomp \- compute the reverse complement
+
+.SH SYNOPSIS
+.nf
+.B #include <dna.h>
+.PP
+.BI "char *dna4_revcomp(const char *" begin ", const char *" end ", const char *" dest ");"
+.fi
+
+.SH DESCRIPTION
+The \fBdna4_revcomp\fR() function efficiently computes the reverse complement. The input string is delimited by \fIbegin\fR and \fIend\fR (exclusive). The result is stored at \fIdest\fR.
+
+The result is undefined if the input string contains characters besides
+.IR A ,
+.IR C ,
+.IR G " and"
+.IR T .
+Lowercase letters are also not allowed.
+
+.SH RETURN VALUE
+The return value points one byte past the last character written (i.e. \fIdest + end - begin\fR). You may want to write a null byte there.
+
+.SH EXAMPLE
+.in +4
+.EX
+const char str[] = "ACGTACGTACGT";
+char buffer[13];
+char *end = dna4_revcomp(str, str + sizeof(str) - 1, buffer);
+*end = '\\0';
+
+assert(strncmp(str, buffer, 12) == 0);
+
+.SH SEE ALSO
+.BR dnax_revcomp (3)

test/Tdna4_revcomp.cxx

@@ -22,6 +22,13 @@ repeat(std::string in, int count)
 
 TEST_CASE("Basic revcomp checks")
 {
+	const char str[] = "ACGTACGTACGT";
+	char buf[13];
+	char *end = dna4_revcomp(str, str + sizeof(str) - 1, buf);
+	*end = (unsigned char)'\0';
+
+	REQUIRE(strncmp(str, buf, 12) == 0);
+
 	auto forward = repeat("ACGT", 10);
 
 	auto buffer = new char[forward.size() + 1];