Changes in uspace/lib/c/generic/str.c [1772e6d:568693b] in mainline

File:

• uspace/lib/c/generic/str.c (modified) (2 diffs)

uspace/lib/c/generic/str.c

@@ -136 +136 @@
 }
 
+/** Decode a single character from a string to the left.
+ *
+ * Decode a single character from a string of size @a size. Decoding starts
+ * at @a offset and this offset is moved to the beginning of the previous
+ * character. In case of decoding error, offset generally decreases at least
+ * by one. However, offset is never moved before 0.
+ *
+ * @param str    String (not necessarily NULL-terminated).
+ * @param offset Byte offset in string where to start decoding.
+ * @param size   Size of the string (in bytes).
+ *
+ * @return Value of decoded character, U_SPECIAL on decoding error or
+ *         NULL if attempt to decode beyond @a start of str.
+ *
+ */
+wchar_t str_decode_reverse(const char *str, size_t *offset, size_t size)
+{
+        if (*offset == 0)
+                return 0;
+        
+        size_t processed = 0;
+        /* Continue while continuation bytes found */
+        while (*offset > 0 && processed < 4) {
+                uint8_t b = (uint8_t) str[--(*offset)];
+                
+                if (processed == 0 && (b & 0x80) == 0) {
+                        /* 0xxxxxxx (Plain ASCII) */
+                        return b & 0x7f;
+                }
+                else if ((b & 0xe0) == 0xc0 || (b & 0xf0) == 0xe0 ||
+                    (b & 0xf8) == 0xf0) {
+                        /* Start byte */
+                        size_t start_offset = *offset;
+                        return str_decode(str, &start_offset, size);
+                }
+                else if ((b & 0xc0) != 0x80) {
+                        /* Not a continuation byte */
+                        return U_SPECIAL;
+                }
+                processed++;
+        }
+        /* Too many continuation bytes */
+        return U_SPECIAL;
+}
+
 /** Encode a single character to string representation.
  *
@@ -397 +442 @@
         
         return len;
+}
+
+/** Get character display width on a character cell display.
+ *
+ * @param ch    Character
+ * @return      Width of character in cells.
+ */
+size_t chr_width(wchar_t ch)
+{
+        return 1;
+}
+
+/** Get string display width on a character cell display.
+ *
+ * @param str   String
+ * @return      Width of string in cells.
+ */
+size_t str_width(const char *str)
+{
+        size_t width = 0;
+        size_t offset = 0;
+        wchar_t ch;
+        
+        while ((ch = str_decode(str, &offset, STR_NO_LIMIT)) != 0)
+                width += chr_width(ch);
+        
+        return width;
 }