[U-Boot] [PATCH v3 1/1] efi_loader: MAX_UTF8_PER_UTF16 = 3

[Heinrich Schuchardt]

The constant MAX_UTF8_PER_UTF16 is used to calculated
required memory when converting from UTF-16 to UTF-8.
If this constant is too big we waste memory.

A code point encoded by one UTF-16 symbol is converted to a
maximum of three UTF-8 symbols, e.g.

0xffff could be encoded as 0xef 0xbf 0xbf.
The first byte carries four bits, the second and third byte
carry six bits each.

A code point encoded by two UTF-16 symbols is converted to four
UTF-8 symbols.

So in this case we need a maximum of two UTF-8 symbols per
UTF-16 symbol.

As the overall maximum is three UTF-8 symobls per UTF-16 symbol
we need MAX_UTF8_PER_UTF16 = 3.

Fixes: 78178bb0c9d lib: add some utf16 handling helpers
Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
The code is only used by efi_loader.
So this patch should go via efi-next.

v3
	fix typo
v2
	rework the commit message
---
 include/charset.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/charset.h b/include/charset.h
index 9c2866bbe6..2f7f7eacc9 100644
--- a/include/charset.h
+++ b/include/charset.h
@@ -9,7 +9,7 @@
 #ifndef __CHARSET_H_
 #define __CHARSET_H_
 
-#define MAX_UTF8_PER_UTF16 4
+#define MAX_UTF8_PER_UTF16 3
 
 /**
  * utf16_strlen() - Get the length of an utf16 string
@@ -52,7 +52,7 @@ uint16_t *utf16_strdup(const uint16_t *s);
  * Converts 'size' characters of the utf16 string 'src' to utf8
  * written to the 'dest' buffer.
  *
- * NOTE that a single utf16 character can generate up to 4 utf8
+ * NOTE that a single utf16 character can generate up to 3 utf8
  * characters.  See MAX_UTF8_PER_UTF16.
  *
  * @dest   the destination buffer to write the utf8 characters
-- 
2.14.1