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Avoid wcwidth(), wcrtomb() and mbrtowc() on ASCII/ISO8859-1 characters.

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ASCII <-> UTF has trivial mappings.  Avoid wcrtomb() and mbrtowc().

ISO-8859-1 is all narrow characters, and cheap to test for.  It might
be possible to cheaply test other popular UTF blocks and/or planes as
well.

These two changes get 2-3x faster input processing on Linux and
FreeBSD.  Performance improvement in actual usage is more modest but
still significant.
This commit is contained in:
john hood
2014-09-28 02:48:32 -04:00
committed by John Hood
parent f5d814a9c4
commit e4a99256cb
3 changed files with 32 additions and 5 deletions
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src/terminal/terminalframebuffer.h
+17 -1
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@@ -126,8 +126,19 @@ namespace Terminal {
bool compare( const Cell &other ) const;
static void append_to_str( std::string &dest, const wchar_t c )
// Is this a printing ISO 8859-1 character?
static bool isprint_iso8859_1( const wchar_t c )
{
return ( c <= 0xff && c >= 0xa0 ) || ( c <= 0x7e && c >= 0x20 );
}
static void append_to_str( std::string &dest, const wchar_t c )
{
/* ASCII? Cheat. */
if ( static_cast<uint32_t>(c) <= 0x7f ) {
dest.push_back( static_cast<char>(c) );
return;
}
static mbstate_t ps = mbstate_t();
char tmp[MB_LEN_MAX];
size_t ignore = wcrtomb(NULL, 0, &ps);
@@ -138,6 +149,11 @@ namespace Terminal {
void append( const wchar_t c )
{
/* ASCII? Cheat. */
if ( static_cast<uint32_t>(c) <= 0x7f ) {
contents.push_back( static_cast<char>(c) );
return;
}
static mbstate_t ps = mbstate_t();
char tmp[MB_LEN_MAX];
size_t ignore = wcrtomb(NULL, 0, &ps);