Feat(libunicode): Added an explicit unicode library

Refactored code to pull out utf8 functions from base into a standalone
library. Also left the required function inside arg.c so that code that
calls ARG_BEGIN doesn't have to link to libunicode.

1 files changed, 26 insertions, 0 deletions

diff --git a/sys/libunicode/findrune.c b/sys/libunicode/findrune.c
new file mode 100644
index 0000000..97edc3c
--- /dev/null
+++ b/sys/libunicode/findrune.c
@@ -0,0 +1,26 @@
+#include "internal.h"
+
+byte*
+utf8·findrune(byte* s, long c)
+{
+    long c1;
+    rune r;
+    int  n;
+
+    if (c < RuneSync) return strchr(s, c);
+
+    for (;;) {
+        c1 = *(ubyte*)s;
+        if (c1 < RuneSelf) {
+            if (c1 == 0) return nil;
+            if (c1 == c) return s;
+            s++;
+            continue;
+        }
+        n = utf8·bytetorune(&r, s);
+        if (r == c) return s;
+        s += n;
+    }
+
+    return nil;
+}