[RFC PATCH 2/3] nls: Simplify ISO-8859-1 implementation

["Pali Rohár" <pali@kernel.org>]

Conversion between ISO-8859-1 and UNICODE code point is simple because all
ISO-8859-1 values has 1:1 mapping in UNICODE code points. ISO-8859-1 is
just subset of UNICODE code points.

So define conversion between ISO-8859-1 and UNICODE code point in
straightforward way.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
 fs/nls/nls_iso8859-1.c | 142 +++--------------------------------------
 1 file changed, 9 insertions(+), 133 deletions(-)

diff --git a/fs/nls/nls_iso8859-1.c b/fs/nls/nls_iso8859-1.c
index 69ac020d43b1..17144c17b40c 100644
--- a/fs/nls/nls_iso8859-1.c
+++ b/fs/nls/nls_iso8859-1.c
@@ -13,129 +13,6 @@
 #include <linux/nls.h>
 #include <linux/errno.h>
 
-static const wchar_t charset2uni[256] = {
-	/* 0x00*/
-	0x0000, 0x0001, 0x0002, 0x0003,
-	0x0004, 0x0005, 0x0006, 0x0007,
-	0x0008, 0x0009, 0x000a, 0x000b,
-	0x000c, 0x000d, 0x000e, 0x000f,
-	/* 0x10*/
-	0x0010, 0x0011, 0x0012, 0x0013,
-	0x0014, 0x0015, 0x0016, 0x0017,
-	0x0018, 0x0019, 0x001a, 0x001b,
-	0x001c, 0x001d, 0x001e, 0x001f,
-	/* 0x20*/
-	0x0020, 0x0021, 0x0022, 0x0023,
-	0x0024, 0x0025, 0x0026, 0x0027,
-	0x0028, 0x0029, 0x002a, 0x002b,
-	0x002c, 0x002d, 0x002e, 0x002f,
-	/* 0x30*/
-	0x0030, 0x0031, 0x0032, 0x0033,
-	0x0034, 0x0035, 0x0036, 0x0037,
-	0x0038, 0x0039, 0x003a, 0x003b,
-	0x003c, 0x003d, 0x003e, 0x003f,
-	/* 0x40*/
-	0x0040, 0x0041, 0x0042, 0x0043,
-	0x0044, 0x0045, 0x0046, 0x0047,
-	0x0048, 0x0049, 0x004a, 0x004b,
-	0x004c, 0x004d, 0x004e, 0x004f,
-	/* 0x50*/
-	0x0050, 0x0051, 0x0052, 0x0053,
-	0x0054, 0x0055, 0x0056, 0x0057,
-	0x0058, 0x0059, 0x005a, 0x005b,
-	0x005c, 0x005d, 0x005e, 0x005f,
-	/* 0x60*/
-	0x0060, 0x0061, 0x0062, 0x0063,
-	0x0064, 0x0065, 0x0066, 0x0067,
-	0x0068, 0x0069, 0x006a, 0x006b,
-	0x006c, 0x006d, 0x006e, 0x006f,
-	/* 0x70*/
-	0x0070, 0x0071, 0x0072, 0x0073,
-	0x0074, 0x0075, 0x0076, 0x0077,
-	0x0078, 0x0079, 0x007a, 0x007b,
-	0x007c, 0x007d, 0x007e, 0x007f,
-	/* 0x80*/
-	0x0080, 0x0081, 0x0082, 0x0083,
-	0x0084, 0x0085, 0x0086, 0x0087,
-	0x0088, 0x0089, 0x008a, 0x008b,
-	0x008c, 0x008d, 0x008e, 0x008f,
-	/* 0x90*/
-	0x0090, 0x0091, 0x0092, 0x0093,
-	0x0094, 0x0095, 0x0096, 0x0097,
-	0x0098, 0x0099, 0x009a, 0x009b,
-	0x009c, 0x009d, 0x009e, 0x009f,
-	/* 0xa0*/
-	0x00a0, 0x00a1, 0x00a2, 0x00a3,
-	0x00a4, 0x00a5, 0x00a6, 0x00a7,
-	0x00a8, 0x00a9, 0x00aa, 0x00ab,
-	0x00ac, 0x00ad, 0x00ae, 0x00af,
-	/* 0xb0*/
-	0x00b0, 0x00b1, 0x00b2, 0x00b3,
-	0x00b4, 0x00b5, 0x00b6, 0x00b7,
-	0x00b8, 0x00b9, 0x00ba, 0x00bb,
-	0x00bc, 0x00bd, 0x00be, 0x00bf,
-	/* 0xc0*/
-	0x00c0, 0x00c1, 0x00c2, 0x00c3,
-	0x00c4, 0x00c5, 0x00c6, 0x00c7,
-	0x00c8, 0x00c9, 0x00ca, 0x00cb,
-	0x00cc, 0x00cd, 0x00ce, 0x00cf,
-	/* 0xd0*/
-	0x00d0, 0x00d1, 0x00d2, 0x00d3,
-	0x00d4, 0x00d5, 0x00d6, 0x00d7,
-	0x00d8, 0x00d9, 0x00da, 0x00db,
-	0x00dc, 0x00dd, 0x00de, 0x00df,
-	/* 0xe0*/
-	0x00e0, 0x00e1, 0x00e2, 0x00e3,
-	0x00e4, 0x00e5, 0x00e6, 0x00e7,
-	0x00e8, 0x00e9, 0x00ea, 0x00eb,
-	0x00ec, 0x00ed, 0x00ee, 0x00ef,
-	/* 0xf0*/
-	0x00f0, 0x00f1, 0x00f2, 0x00f3,
-	0x00f4, 0x00f5, 0x00f6, 0x00f7,
-	0x00f8, 0x00f9, 0x00fa, 0x00fb,
-	0x00fc, 0x00fd, 0x00fe, 0x00ff,
-};
-
-static const unsigned char page00[256] = {
-	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, /* 0x00-0x07 */
-	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, /* 0x08-0x0f */
-	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, /* 0x10-0x17 */
-	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, /* 0x18-0x1f */
-	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, /* 0x20-0x27 */
-	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, /* 0x28-0x2f */
-	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, /* 0x30-0x37 */
-	0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, /* 0x38-0x3f */
-	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, /* 0x40-0x47 */
-	0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, /* 0x48-0x4f */
-	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, /* 0x50-0x57 */
-	0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, /* 0x58-0x5f */
-	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, /* 0x60-0x67 */
-	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, /* 0x68-0x6f */
-	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, /* 0x70-0x77 */
-	0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, /* 0x78-0x7f */
-
-	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, /* 0x80-0x87 */
-	0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, /* 0x88-0x8f */
-	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, /* 0x90-0x97 */
-	0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, /* 0x98-0x9f */
-	0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, /* 0xa0-0xa7 */
-	0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, /* 0xa8-0xaf */
-	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, /* 0xb0-0xb7 */
-	0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, /* 0xb8-0xbf */
-	0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, /* 0xc0-0xc7 */
-	0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, /* 0xc8-0xcf */
-	0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, /* 0xd0-0xd7 */
-	0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, /* 0xd8-0xdf */
-	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, /* 0xe0-0xe7 */
-	0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, /* 0xe8-0xef */
-	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, /* 0xf0-0xf7 */
-	0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, /* 0xf8-0xff */
-};
-
-static const unsigned char *const page_uni2charset[256] = {
-	page00, NULL,   NULL,   NULL,   NULL,   NULL,   NULL,   NULL,   
-};
-
 static const unsigned char charset2lower[256] = {
 	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, /* 0x00-0x07 */
 	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, /* 0x08-0x0f */
@@ -210,26 +87,25 @@ static const unsigned char charset2upper[256] = {
 
 static int uni2char(wchar_t uni, unsigned char *out, int boundlen)
 {
-	const unsigned char *uni2charset;
-	unsigned char cl = uni & 0x00ff;
-	unsigned char ch = (uni & 0xff00) >> 8;
-
 	if (boundlen <= 0)
 		return -ENAMETOOLONG;
 
-	uni2charset = page_uni2charset[ch];
-	if (uni2charset && uni2charset[cl])
-		out[0] = uni2charset[cl];
-	else
+	if (!uni || uni > 255)
 		return -EINVAL;
+
+	out[0] = uni;
 	return 1;
 }
 
 static int char2uni(const unsigned char *rawstring, int boundlen, wchar_t *uni)
 {
-	*uni = charset2uni[*rawstring];
-	if (*uni == 0x0000)
+	if (boundlen <= 0)
+		return -ENAMETOOLONG;
+
+	if (!*rawstring)
 		return -EINVAL;
+
+	*uni = *rawstring;
 	return 1;
 }
 
-- 
2.20.1