1 files changed, 66 insertions, 0 deletions
diff --git a/src/utf8.c b/src/utf8.c
new file mode 100644
index 0000000..177f76d
--- /dev/null
+++ b/src/utf8.c
@@ -0,0 +1,66 @@
+#include "aplos.h"
+
+int
+utf8_char_length(const char8_t *p)
+{
+	uint8_t v = *p;
+	if((v >> 5) == 0b110)
+		return 2;
+	if((v >> 4) == 0b1110)
+		return 3;
+	if((v >> 3) == 0b11110)
+		return 4;
+	return 1;
+}
+
+int
+utf8_cmp_n(const char8_t *a, const char8_t *b, uint64_t n)
+{
+	uint32_t aval, bval;
+	while(*a && *b && n){
+		aval = utf8_value(a);
+		bval = utf8_value(b);
+
+		if(aval < bval)
+			return -1;
+		if(aval > bval)
+			return 1;
+		a += utf8_char_length(a);
+		b += utf8_char_length(b);
+		n--;
+	}
+	if((n == 0) || (*a == *b))
+		return 0;
+	if(*a)
+		return 1;
+	else
+		return -1;
+}
+
+uint32_t
+utf8_value(const char8_t *p)
+{
+	uint32_t v = 0;
+	int n = utf8_char_length(p);
+	switch(n){
+	case 1:
+		v = *p;
+		break;
+	case 2:
+		v = *p & 0b00011111;
+		break;
+	case 3:
+		v = *p & 0b00001111;
+		break;
+	case 4:
+		v = *p & 0b00000111;
+		break;
+	}
+
+	while(--n){
+		p++;
+		v <<= 6;
+		v |= *p & 0b00111111;
+	}
+	return v;
+}