1 files changed, 80 insertions, 0 deletions
diff --git a/src/common/impl/strutil.c b/src/common/impl/strutil.c
new file mode 100644
index 0000000..3a801f7
--- /dev/null
+++ b/src/common/impl/strutil.c
@@ -0,0 +1,80 @@
+#include "common/strutil.h"
+
+uint8_t ffUtf8CharLenWidth(const char* str, uint32_t length, uint8_t* width) {
+    if (__builtin_expect(length == 0 || *str == '\0', false)) {
+        if (width) {
+            *width = 0;
+        }
+        return 0;
+    }
+
+    unsigned char first = (unsigned char) *str;
+    if (__builtin_expect(first < 0x80, true)) {
+        if (width) {
+            *width = 1;
+        }
+        return 1;
+    }
+
+    uint8_t bytes;
+    if ((first & 0xE0) == 0xC0) {
+        bytes = 2;
+    } else if ((first & 0xF0) == 0xE0) {
+        bytes = 3;
+    } else if ((first & 0xF8) == 0xF0) {
+        bytes = 4;
+    } else {
+        if (width) {
+            *width = 1;
+        }
+        return 1;
+    }
+
+    if (length < bytes) {
+        if (width) {
+            *width = 1;
+        }
+        return 1;
+    }
+
+    for (uint8_t i = 1; i < bytes; ++i) {
+        unsigned char continuation = (unsigned char) str[i];
+        if (continuation == '\0' || (continuation & 0xC0) != 0x80) {
+            if (width) {
+                *width = 1;
+            }
+            return 1;
+        }
+    }
+
+    uint32_t ucs = (uint32_t) (first & ((1U << (8 - bytes)) - 1));
+    for (uint8_t i = 1; i < bytes; ++i) {
+        ucs <<= 6;
+        ucs |= (uint32_t) ((unsigned char) str[i] & 0x3F);
+    }
+
+    int wcWidth = mk_wcwidth(ucs);
+    if (width) {
+        *width = (uint8_t) (wcWidth < 0 ? 0 : wcWidth);
+    }
+    return bytes;
+}
+
+uint32_t ffUtf8StrWidth(const char* str, uint32_t length) {
+    uint32_t result = 0;
+    const char* ptr = str;
+
+    while (length > 0 && *ptr != '\0') {
+        uint8_t width = 0;
+        uint8_t bytes = ffUtf8CharLenWidth(ptr, length, &width);
+        if (__builtin_expect(bytes == 0, false)) {
+            break;
+        }
+
+        result += width;
+        ptr += bytes;
+        length -= bytes;
+    }
+
+    return result > 0 ? result : (uint32_t) (ptr - str);
+}