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optimize Shift_JIS iconv converter
- From: Bruno Haible <bruno at clisp dot org>
- To: libc-alpha at sources dot redhat dot com
- Date: Wed, 17 Apr 2002 16:49:37 +0200 (CEST)
- Subject: optimize Shift_JIS iconv converter
Here is an optimization of the Shift_JIS converter: Use a simple addition
instead of an array access.
2002-04-15 Bruno Haible <bruno@clisp.org>
* iconvdata/sjis.c (halfkana_to_ucs4): Remove array.
(BODY for FROM_LOOP): Optimize the JISX0201:GR to Unicode conversion.
--- glibc-20020408/iconvdata/sjis.c.bak 2001-08-15 21:39:08.000000000 +0200
+++ glibc-20020408/iconvdata/sjis.c 2002-04-16 02:16:55.000000000 +0200
@@ -1,5 +1,5 @@
/* Mapping tables for SJIS handling.
- Copyright (C) 1997, 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
+ Copyright (C) 1997-1999, 2000-2002 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
@@ -22,18 +22,6 @@
#include <stdint.h>
#include <wchar.h>
-static const uint32_t halfkana_to_ucs4[] =
-{
- 0xff61, 0xff62, 0xff63, 0xff64, 0xff65, 0xff66, 0xff67, 0xff68,
- 0xff69, 0xff6a, 0xff6b, 0xff6c, 0xff6d, 0xff6e, 0xff6f, 0xff70,
- 0xff71, 0xff72, 0xff73, 0xff74, 0xff75, 0xff76, 0xff77, 0xff78,
- 0xff79, 0xff7a, 0xff7b, 0xff7c, 0xff7d, 0xff7e, 0xff7f, 0xff80,
- 0xff81, 0xff82, 0xff83, 0xff84, 0xff85, 0xff86, 0xff87, 0xff88,
- 0xff89, 0xff8a, 0xff8b, 0xff8c, 0xff8d, 0xff8e, 0xff8f, 0xff90,
- 0xff91, 0xff92, 0xff93, 0xff94, 0xff95, 0xff96, 0xff97, 0xff98,
- 0xff99, 0xff9a, 0xff9b, 0xff9c, 0xff9d, 0xff9e, 0xff9f
-};
-
/* The following table can be generated from the file
unix/mappings/eastasia/jis/shiftjis.txt
@@ -4357,7 +4345,7 @@
++inptr; \
else if (ch >= 0xa1 && ch <= 0xdf) \
{ \
- ch = halfkana_to_ucs4[ch - 0xa1]; \
+ ch += 0xfec0; \
++inptr; \
} \
else if (__builtin_expect (ch > 0xea, 0) \
@@ -4378,14 +4366,14 @@
} \
else \
{ \
- /* Two-byte character. First test whether the next character \
+ /* Two-byte character. First test whether the next byte \
is also available. */ \
uint32_t ch2; \
uint_fast32_t idx; \
\
if (__builtin_expect (inptr + 1 >= inend, 0)) \
{ \
- /* The second character is not available. Store \
+ /* The second byte is not available. Store \
the intermediate result. */ \
result = __GCONV_INCOMPLETE_INPUT; \
break; \