From 29b56ef4e4113bcd091b19d6926f18814162ca53 Mon Sep 17 00:00:00 2001
From: Nicholas Noll <nbnoll@eml.cc>
Date: Tue, 26 Oct 2021 21:01:41 -0700
Subject: 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.
---
 sys/libunicode/findlastrune.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 sys/libunicode/findlastrune.c

(limited to 'sys/libunicode/findlastrune.c')

diff --git a/sys/libunicode/findlastrune.c b/sys/libunicode/findlastrune.c
new file mode 100644
index 0000000..0dc5032
--- /dev/null
+++ b/sys/libunicode/findlastrune.c
@@ -0,0 +1,29 @@
+#include "internal.h"
+
+byte*
+utf8·findlastrune(byte* s, long c)
+{
+    long c1;
+    rune r;
+    byte *l;
+
+    if (c < RuneSync)
+        return strrchr(s, c);
+
+    l = nil;
+    for(;;){
+        c1 = *(ubyte*)s;
+        if (c1 < RuneSelf) {
+            if (c1 == 0) return l;
+            if (c1 == c) l = s;
+            s++;
+            continue;
+        }
+        c1 = utf8·bytetorune(&r, s);
+        if (r == c) 
+            l = s;
+        s += c1;
+    }
+
+    return nil;
+}
-- 
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