1 files changed, 38 insertions, 0 deletions
diff --git a/src/libutf/internal.h b/src/libutf/internal.h
new file mode 100644
index 0000000..9719977
--- /dev/null
+++ b/src/libutf/internal.h
@@ -0,0 +1,38 @@
+#pragma once
+
+#include <u.h>
+#include <base.h>
+#include <libutf.h>
+
+/*
+ * NOTE: we use the preprocessor to ensure we have unsigned constants.
+ * UTF-8 code:
+ * 1 byte:
+ * 0xxxxxxx
+ * 2 byte:
+ * 110xxxxx 10xxxxxx
+ * 3 byte:
+ * 1110xxxx 10xxxxxx 10xxxxxx
+ * 4 byte:
+ * 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+ */
+
+#define Tx     0x80u // 0b10000000 transfer header
+#define TMask  0x3Fu // 0b00111111 transfer mask
+
+#define TByte1 0xC0u // 0b11000000
+#define TByte2 0xE0u // 0b11100000
+#define TByte3 0xF0u // 0b11110000
+#define TByte4 0xF8u // 0b11111000
+
+#define RuneMask  0x1FFFFFu
+
+#define Rune1Byte 0x000080u  // 1 << 8   (1 byte)
+#define Rune2Byte 0x001000u  // 1 << 12  (2 bytes)
+#define Rune3Byte 0x020000u  // 1 << 17  (3 bytes)
+#define Rune4Byte 0x400000u  // 1 << 22  (4 bytes)
+
+
+/* UTF-16 nonsense */
+#define RuneSurrogateMin 0x0D8000
+#define RuneSurrogateMax 0x0D8FFF