1 files changed, 97 insertions, 0 deletions
diff --git a/vendor/librune/lib/utf8/u8chr.c b/vendor/librune/lib/utf8/u8chr.c
new file mode 100644
index 0000000..4ecbd10
--- /dev/null
+++ b/vendor/librune/lib/utf8/u8chr.c
@@ -0,0 +1,97 @@
+#include <stdint.h>
+#include <string.h>
+
+#include "utf8.h"
+
+#include "internal/common.h"
+
+/* NOTE: The memmem*() functions were taken directly from the memmem()
+   implementation on OpenBSD.  As a result, these functions are licensed under
+   OpenBSDs 2-Clause BSD License instead of this libraries 0-Clause BSD License.
+
+   The license for these functions is as follows:
+
+       Copyright © 2005–2020 Rich Felker, et al.
+
+       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. */
+
+static const char8_t *
+memmem2(const char8_t *h, size_t k, const char8_t *n)
+{
+	uint16_t hw, nw;
+	hw = h[0] << 8 | h[1];
+	nw = n[0] << 8 | n[1];
+
+	for (h += 2, k -= 2; k; k--, hw = hw << 8 | *h++) {
+		if (hw == nw)
+			return h - 2;
+	}
+	return hw == nw ? h - 2 : nullptr;
+}
+
+static const char8_t *
+memmem3(const char8_t *h, size_t k, const char8_t *n)
+{
+	uint32_t hw, nw;
+	hw = h[0] << 24 | h[1] << 16 | h[2] << 8;
+	nw = n[0] << 24 | n[1] << 16 | n[2] << 8;
+
+	for (h += 3, k -= 3; k; k--, hw = (hw | *h++) << 8) {
+		if (hw == nw)
+			return h - 3;
+	}
+	return hw == nw ? h - 3 : nullptr;
+}
+
+static const char8_t *
+memmem4(const char8_t *h, size_t k, const char8_t *n)
+{
+	uint32_t hw, nw;
+	hw = h[0] << 24 | h[1] << 16 | h[2] << 8 | h[3];
+	nw = n[0] << 24 | n[1] << 16 | n[2] << 8 | n[3];
+
+	for (h += 4, k -= 4; k; k--, hw = hw << 8 | *h++) {
+		if (hw == nw)
+			return h - 4;
+	}
+	return hw == nw ? h - 4 : nullptr;
+}
+
+const char8_t *
+u8chr(const char8_t *s, rune ch, size_t n)
+{
+	char8_t buf[U8_LEN_MAX];
+	int m = rtou8(buf, ch, sizeof(buf));
+
+	if (n < (size_t)m)
+		return nullptr;
+	switch (m) {
+	case 1:
+		return memchr(s, ch, n);
+	case 2:
+		return memmem2(s, n, buf);
+	case 3:
+		return memmem3(s, n, buf);
+	case 4:
+		return memmem4(s, n, buf);
+	}
+
+	unreachable();
+}