1 files changed, 95 insertions, 0 deletions
diff --git a/tools/src/tinf/adler32.c b/tools/src/tinf/adler32.c
new file mode 100644
index 0000000..5b3c54f
--- /dev/null
+++ b/tools/src/tinf/adler32.c
@@ -0,0 +1,95 @@
+/*
+ * Adler-32 checksum
+ *
+ * Copyright (c) 2003-2019 Joergen Ibsen
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty. In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ *   1. The origin of this software must not be misrepresented; you must
+ *      not claim that you wrote the original software. If you use this
+ *      software in a product, an acknowledgment in the product
+ *      documentation would be appreciated but is not required.
+ *
+ *   2. Altered source versions must be plainly marked as such, and must
+ *      not be misrepresented as being the original software.
+ *
+ *   3. This notice may not be removed or altered from any source
+ *      distribution.
+ */
+
+/*
+ * Adler-32 algorithm taken from the zlib source, which is
+ * Copyright (C) 1995-1998 Jean-loup Gailly and Mark Adler
+ */
+
+#include "tinf.h"
+
+#define A32_BASE 65521
+#define A32_NMAX 5552
+
+unsigned int tinf_adler32(const void *data, unsigned int length)
+{
+	const unsigned char *buf = (const unsigned char *) data;
+
+	unsigned int s1 = 1;
+	unsigned int s2 = 0;
+
+	while (length > 0) {
+		int k = length < A32_NMAX ? length : A32_NMAX;
+		int i;
+
+		for (i = k / 16; i; --i, buf += 16) {
+			s1 += buf[0];
+			s2 += s1;
+			s1 += buf[1];
+			s2 += s1;
+			s1 += buf[2];
+			s2 += s1;
+			s1 += buf[3];
+			s2 += s1;
+			s1 += buf[4];
+			s2 += s1;
+			s1 += buf[5];
+			s2 += s1;
+			s1 += buf[6];
+			s2 += s1;
+			s1 += buf[7];
+			s2 += s1;
+
+			s1 += buf[8];
+			s2 += s1;
+			s1 += buf[9];
+			s2 += s1;
+			s1 += buf[10];
+			s2 += s1;
+			s1 += buf[11];
+			s2 += s1;
+			s1 += buf[12];
+			s2 += s1;
+			s1 += buf[13];
+			s2 += s1;
+			s1 += buf[14];
+			s2 += s1;
+			s1 += buf[15];
+			s2 += s1;
+		}
+
+		for (i = k % 16; i; --i) {
+			s1 += *buf++;
+			s2 += s1;
+		}
+
+		s1 %= A32_BASE;
+		s2 %= A32_BASE;
+
+		length -= k;
+	}
+
+	return (s2 << 16) | s1;
+}