progress

1 files changed, 49 insertions, 0 deletions

diff --git a/util.c b/util.c
index fe044fc..9b3a783 100644
--- a/util.c
+++ b/util.c
@@ -6,6 +6,11 @@
 
 #include "util.h"
 
+static const unsigned char utfbyte[UTF_SIZ + 1] = {0x80,    0, 0xC0, 0xE0, 0xF0};
+static const unsigned char utfmask[UTF_SIZ + 1] = {0xC0, 0x80, 0xE0, 0xF0, 0xF8};
+static const long utfmin[UTF_SIZ + 1] = {       0,    0,  0x80,  0x800,  0x10000};
+static const long utfmax[UTF_SIZ + 1] = {0x10FFFF, 0x7F, 0x7FF, 0xFFFF, 0x10FFFF};
+
 void *
 ecalloc(size_t nmemb, size_t size)
 {
@@ -33,3 +38,47 @@ die(const char *fmt, ...) {
 
 	exit(1);
 }
+
+long
+utf8decodebyte(const char c, size_t *i)
+{
+	for (*i = 0; *i < (UTF_SIZ + 1); ++(*i))
+		if (((unsigned char)c & utfmask[*i]) == utfbyte[*i])
+			return (unsigned char)c & ~utfmask[*i];
+	return 0;
+}
+
+size_t
+utf8validate(long *u, size_t i)
+{
+	if (!BETWEEN(*u, utfmin[i], utfmax[i]) || BETWEEN(*u, 0xD800, 0xDFFF))
+		*u = UTF_INVALID;
+	for (i = 1; *u > utfmax[i]; ++i)
+		;
+	return i;
+}
+
+size_t
+utf8decode(const char *c, long *u, size_t clen)
+{
+	size_t i, j, len, type;
+	long udecoded;
+
+	*u = UTF_INVALID;
+	if (!clen)
+		return 0;
+	udecoded = utf8decodebyte(c[0], &len);
+	if (!BETWEEN(len, 1, UTF_SIZ))
+		return 1;
+	for (i = 1, j = 1; i < clen && j < len; ++i, ++j) {
+		udecoded = (udecoded << 6) | utf8decodebyte(c[i], &type);
+		if (type)
+			return j;
+	}
+	if (j < len)
+		return 0;
+	*u = udecoded;
+	utf8validate(u, len);
+
+	return len;
+}