1 files changed, 69 insertions, 0 deletions
diff --git a/sys/libutf/encode.c b/sys/libutf/encode.c
new file mode 100644
index 0000000..fa7c93e
--- /dev/null
+++ b/sys/libutf/encode.c
@@ -0,0 +1,69 @@
+#include "internal.h"
+
+int
+utf8·encode(rune *r, byte *s)
+{
+    rune c;
+
+    c = *r;
+    if(c < Rune1Byte){ // 7 bits
+        s[0] = (uint8)c;
+        return 1;
+    }
+
+    if(c < Rune2Byte){ // 11 bits
+        s[0] = TByte1 | (c >> 6);
+        s[1] = Tx     | (c & TMask);
+        return 2;
+    }
+
+    if(c < Rune3Byte){ // 16 bits
+        s[0] = TByte2 | ((c >> 12));
+        s[1] = Tx     | ((c >> 6) & TMask);
+        s[2] = Tx     | ((c)      & TMask);
+        return 3;
+    }
+
+    // 22 bits
+    if(c > RuneMax || (RuneSurrogateMin <= c && c <= RuneSurrogateMax))
+        c = RuneErr;
+
+    s[0] = TByte3 | ((c >> 18));
+    s[1] = Tx     | ((c >> 12) & TMask);
+    s[2] = Tx     | ((c >> 6)  & TMask);
+    s[3] = Tx     | ((c)       & TMask);
+
+    return 4;
+}
+
+#if 0
+int
+utf8·encode(rune* r, byte* s)
+{
+    int i, j;
+    rune c;
+
+    c = *r;
+    if(c <= Rune1) {
+        s[0] = c;
+        return 1;
+    }
+
+    for(i = 2; i < UTFmax + 1; i++){
+        if(i == 3){
+            if(c > RuneMax)
+                c = RuneErr;
+            if(SurrogateMin <= c && c <= SurrogateMax)
+                c = RuneErr;
+        }
+        if(c <= RuneX(i) || i == UTFmax) {
+            s[0] = Tbyte(i) |  (c >> (i - 1)*Bitx);
+            for(j = 1; j < i; j++)
+                s[j] = Tx | ((c >> (i - j - 1)*Bitx) & Maskx);
+            return i;
+        }
+    }
+
+    return UTFmax;
+}
+#endif