Initial import.

src/int/i32_encode.c

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining 
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be 
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "inner.h"
+
+/* see inner.h */
+void
+br_i32_encode(void *dst, size_t len, const uint32_t *x)
+{
+	unsigned char *buf;
+	size_t k;
+
+	buf = dst;
+
+	/*
+	 * Compute the announced size of x in bytes; extra bytes are
+	 * filled with zeros.
+	 */
+	k = (x[0] + 7) >> 3;
+	while (len > k) {
+		*buf ++ = 0;
+		len --;
+	}
+
+	/*
+	 * Now we use k as index within x[]. That index starts at 1;
+	 * we initialize it to the topmost complete word, and process
+	 * any remaining incomplete word.
+	 */
+	k = (len + 3) >> 2;
+	switch (len & 3) {
+	case 3:
+		*buf ++ = x[k] >> 16;
+		/* fall through */
+	case 2:
+		*buf ++ = x[k] >> 8;
+		/* fall through */
+	case 1:
+		*buf ++ = x[k];
+		k --;
+	}
+
+	/*
+	 * Encode all complete words.
+	 */
+	while (k > 0) {
+		br_enc32be(buf, x[k]);
+		k --;
+		buf += 4;
+	}
+}