1 /*****************************************************************************
2 * libc.c: Extra libc function for some systems.
3 *****************************************************************************
4 * Copyright (C) 2002-2006 VLC authors and VideoLAN
6 * Authors: Gildas Bazin <gbazin@videolan.org>
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU Lesser General Public License as published by
10 * the Free Software Foundation; either version 2.1 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public License
19 * along with this program; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
21 *****************************************************************************/
26 #include <vlc_common.h>
27 #include <vlc_charset.h>
36 #if defined(HAVE_ICONV)
40 #if defined(__OS2__) && defined(__INNOTEK_LIBC__)
43 typedef struct os2_iconv_t
49 /*****************************************************************************
50 * Local conversion routine from ISO_6937 to UTF-8 charset. Support for this
51 * is still missing in libiconv, hence multiple operating systems lack it.
52 * The conversion table adds Euro sign (0xA4) as per ETSI EN 300 468 Annex A
53 *****************************************************************************/
55 static const uint16_t to_ucs4
[128] =
57 /* 0x80 */ 0x0080, 0x0081, 0x0082, 0x0083, 0x0084, 0x0085, 0x0086, 0x0087,
58 /* 0x88 */ 0x0088, 0x0089, 0x008a, 0x008b, 0x008c, 0x008d, 0x008e, 0x008f,
59 /* 0x90 */ 0x0090, 0x0091, 0x0092, 0x0093, 0x0094, 0x0095, 0x0096, 0x0097,
60 /* 0x98 */ 0x0098, 0x0099, 0x009a, 0x009b, 0x009c, 0x009d, 0x009e, 0x009f,
61 /* 0xa0 */ 0x00a0, 0x00a1, 0x00a2, 0x00a3, 0x20ac, 0x00a5, 0x0000, 0x00a7,
62 /* 0xa8 */ 0x00a4, 0x2018, 0x201c, 0x00ab, 0x2190, 0x2191, 0x2192, 0x2193,
63 /* 0xb0 */ 0x00b0, 0x00b1, 0x00b2, 0x00b3, 0x00d7, 0x00b5, 0x00b6, 0x00b7,
64 /* 0xb8 */ 0x00f7, 0x2019, 0x201d, 0x00bb, 0x00bc, 0x00bd, 0x00be, 0x00bf,
65 /* 0xc0 */ 0x0000, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff,
66 /* 0xc8 */ 0xffff, 0x0000, 0xffff, 0xffff, 0x0000, 0xffff, 0xffff, 0xffff,
67 /* 0xd0 */ 0x2014, 0x00b9, 0x00ae, 0x00a9, 0x2122, 0x266a, 0x00ac, 0x00a6,
68 /* 0xd8 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x215b, 0x215c, 0x215d, 0x215e,
69 /* 0xe0 */ 0x2126, 0x00c6, 0x00d0, 0x00aa, 0x0126, 0x0000, 0x0132, 0x013f,
70 /* 0xe8 */ 0x0141, 0x00d8, 0x0152, 0x00ba, 0x00de, 0x0166, 0x014a, 0x0149,
71 /* 0xf0 */ 0x0138, 0x00e6, 0x0111, 0x00f0, 0x0127, 0x0131, 0x0133, 0x0140,
72 /* 0xf8 */ 0x0142, 0x00f8, 0x0153, 0x00df, 0x00fe, 0x0167, 0x014b, 0x00ad
75 /* The outer array range runs from 0xc1 to 0xcf, the inner range from 0x40
77 static const uint16_t to_ucs4_comb
[15][64] =
81 /* 0x40 */ 0x0000, 0x00c0, 0x0000, 0x0000, 0x0000, 0x00c8, 0x0000, 0x0000,
82 /* 0x48 */ 0x0000, 0x00cc, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x00d2,
83 /* 0x50 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x00d9, 0x0000, 0x0000,
84 /* 0x58 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
85 /* 0x60 */ 0x0000, 0x00e0, 0x0000, 0x0000, 0x0000, 0x00e8, 0x0000, 0x0000,
86 /* 0x68 */ 0x0000, 0x00ec, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x00f2,
87 /* 0x70 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x00f9, 0x0000, 0x0000,
88 /* 0x78 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
92 /* 0x40 */ 0x0000, 0x00c1, 0x0000, 0x0106, 0x0000, 0x00c9, 0x0000, 0x0000,
93 /* 0x48 */ 0x0000, 0x00cd, 0x0000, 0x0000, 0x0139, 0x0000, 0x0143, 0x00d3,
94 /* 0x50 */ 0x0000, 0x0000, 0x0154, 0x015a, 0x0000, 0x00da, 0x0000, 0x0000,
95 /* 0x58 */ 0x0000, 0x00dd, 0x0179, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
96 /* 0x60 */ 0x0000, 0x00e1, 0x0000, 0x0107, 0x0000, 0x00e9, 0x0000, 0x0000,
97 /* 0x68 */ 0x0000, 0x00ed, 0x0000, 0x0000, 0x013a, 0x0000, 0x0144, 0x00f3,
98 /* 0x70 */ 0x0000, 0x0000, 0x0155, 0x015b, 0x0000, 0x00fa, 0x0000, 0x0000,
99 /* 0x78 */ 0x0000, 0x00fd, 0x017a, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
103 /* 0x40 */ 0x0000, 0x00c2, 0x0000, 0x0108, 0x0000, 0x00ca, 0x0000, 0x011c,
104 /* 0x48 */ 0x0124, 0x00ce, 0x0134, 0x0000, 0x0000, 0x0000, 0x0000, 0x00d4,
105 /* 0x50 */ 0x0000, 0x0000, 0x0000, 0x015c, 0x0000, 0x00db, 0x0000, 0x0174,
106 /* 0x58 */ 0x0000, 0x0176, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
107 /* 0x60 */ 0x0000, 0x00e2, 0x0000, 0x0109, 0x0000, 0x00ea, 0x0000, 0x011d,
108 /* 0x68 */ 0x0125, 0x00ee, 0x0135, 0x0000, 0x0000, 0x0000, 0x0000, 0x00f4,
109 /* 0x70 */ 0x0000, 0x0000, 0x0000, 0x015d, 0x0000, 0x00fb, 0x0000, 0x0175,
110 /* 0x78 */ 0x0000, 0x0177, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
114 /* 0x40 */ 0x0000, 0x00c3, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
115 /* 0x48 */ 0x0000, 0x0128, 0x0000, 0x0000, 0x0000, 0x0000, 0x00d1, 0x00d5,
116 /* 0x50 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0168, 0x0000, 0x0000,
117 /* 0x58 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
118 /* 0x60 */ 0x0000, 0x00e3, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
119 /* 0x68 */ 0x0000, 0x0129, 0x0000, 0x0000, 0x0000, 0x0000, 0x00f1, 0x00f5,
120 /* 0x70 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0169, 0x0000, 0x0000,
121 /* 0x78 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
125 /* 0x40 */ 0x0000, 0x0100, 0x0000, 0x0000, 0x0000, 0x0112, 0x0000, 0x0000,
126 /* 0x48 */ 0x0000, 0x012a, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x014c,
127 /* 0x50 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x016a, 0x0000, 0x0000,
128 /* 0x58 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
129 /* 0x60 */ 0x0000, 0x0101, 0x0000, 0x0000, 0x0000, 0x0113, 0x0000, 0x0000,
130 /* 0x68 */ 0x0000, 0x012b, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x014d,
131 /* 0x70 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x016b, 0x0000, 0x0000,
132 /* 0x78 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
136 /* 0x40 */ 0x0000, 0x0102, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x011e,
137 /* 0x48 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
138 /* 0x50 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x016c, 0x0000, 0x0000,
139 /* 0x58 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
140 /* 0x60 */ 0x0000, 0x0103, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x011f,
141 /* 0x68 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
142 /* 0x70 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x016d, 0x0000, 0x0000,
143 /* 0x78 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
147 /* 0x40 */ 0x0000, 0x0000, 0x0000, 0x010a, 0x0000, 0x0116, 0x0000, 0x0120,
148 /* 0x48 */ 0x0000, 0x0130, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
149 /* 0x50 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
150 /* 0x58 */ 0x0000, 0x0000, 0x017b, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
151 /* 0x60 */ 0x0000, 0x0000, 0x0000, 0x010b, 0x0000, 0x0117, 0x0000, 0x0121,
152 /* 0x68 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
153 /* 0x70 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
154 /* 0x78 */ 0x0000, 0x0000, 0x017c, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
158 /* 0x40 */ 0x0000, 0x00c4, 0x0000, 0x0000, 0x0000, 0x00cb, 0x0000, 0x0000,
159 /* 0x48 */ 0x0000, 0x00cf, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x00d6,
160 /* 0x50 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x00dc, 0x0000, 0x0000,
161 /* 0x58 */ 0x0000, 0x0178, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
162 /* 0x60 */ 0x0000, 0x00e4, 0x0000, 0x0000, 0x0000, 0x00eb, 0x0000, 0x0000,
163 /* 0x68 */ 0x0000, 0x00ef, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x00f6,
164 /* 0x70 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x00fc, 0x0000, 0x0000,
165 /* 0x78 */ 0x0000, 0x00ff, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
173 /* 0x40 */ 0x0000, 0x00c5, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
174 /* 0x48 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
175 /* 0x50 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x016e, 0x0000, 0x0000,
176 /* 0x58 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
177 /* 0x60 */ 0x0000, 0x00e5, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
178 /* 0x68 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
179 /* 0x70 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x016f, 0x0000, 0x0000,
180 /* 0x78 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
184 /* 0x40 */ 0x0000, 0x0000, 0x0000, 0x00c7, 0x0000, 0x0000, 0x0000, 0x0122,
185 /* 0x48 */ 0x0000, 0x0000, 0x0000, 0x0136, 0x013b, 0x0000, 0x0145, 0x0000,
186 /* 0x50 */ 0x0000, 0x0000, 0x0156, 0x015e, 0x0162, 0x0000, 0x0000, 0x0000,
187 /* 0x58 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
188 /* 0x60 */ 0x0000, 0x0000, 0x0000, 0x00e7, 0x0000, 0x0000, 0x0000, 0x0123,
189 /* 0x68 */ 0x0000, 0x0000, 0x0000, 0x0137, 0x013c, 0x0000, 0x0146, 0x0000,
190 /* 0x70 */ 0x0000, 0x0000, 0x0157, 0x015f, 0x0163, 0x0000, 0x0000, 0x0000,
191 /* 0x78 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
199 /* 0x40 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
200 /* 0x48 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0150,
201 /* 0x50 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0170, 0x0000, 0x0000,
202 /* 0x58 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
203 /* 0x60 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
204 /* 0x68 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0151,
205 /* 0x70 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0171, 0x0000, 0x0000,
206 /* 0x78 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
210 /* 0x40 */ 0x0000, 0x0104, 0x0000, 0x0000, 0x0000, 0x0118, 0x0000, 0x0000,
211 /* 0x48 */ 0x0000, 0x012e, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
212 /* 0x50 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0172, 0x0000, 0x0000,
213 /* 0x58 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
214 /* 0x60 */ 0x0000, 0x0105, 0x0000, 0x0000, 0x0000, 0x0119, 0x0000, 0x0000,
215 /* 0x68 */ 0x0000, 0x012f, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
216 /* 0x70 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0173, 0x0000, 0x0000,
217 /* 0x78 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
221 /* 0x40 */ 0x0000, 0x0000, 0x0000, 0x010c, 0x010e, 0x011a, 0x0000, 0x0000,
222 /* 0x48 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x013d, 0x0000, 0x0147, 0x0000,
223 /* 0x50 */ 0x0000, 0x0000, 0x0158, 0x0160, 0x0164, 0x0000, 0x0000, 0x0000,
224 /* 0x58 */ 0x0000, 0x0000, 0x017d, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
225 /* 0x60 */ 0x0000, 0x0000, 0x0000, 0x010d, 0x010f, 0x011b, 0x0000, 0x0000,
226 /* 0x68 */ 0x0000, 0x0000, 0x0000, 0x0000, 0x013e, 0x0000, 0x0148, 0x0000,
227 /* 0x70 */ 0x0000, 0x0000, 0x0159, 0x0161, 0x0165, 0x0000, 0x0000, 0x0000,
228 /* 0x78 */ 0x0000, 0x0000, 0x017e, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000
232 static size_t ISO6937toUTF8( const char **inbuf
, size_t *inbytesleft
,
233 unsigned char **outbuf
, size_t *outbytesleft
)
237 if( !inbuf
|| !(*inbuf
) )
238 return (size_t)(0); /* Reset state requested */
240 const char *iptr
= *inbuf
;
241 const char *iend
= iptr
+ *inbytesleft
;
242 unsigned char *optr
= *outbuf
;
243 unsigned char *oend
= optr
+ *outbytesleft
;
246 while ( iptr
< iend
)
248 unsigned char c1
= *iptr
;
255 break; /* No space in outbuf */
262 if ( optr
+ 2 >= oend
)
265 break; /* No space in outbuf for multibyte char */
268 uint_fast16_t ch
= to_ucs4
[c1
- 0x80];
272 /* Composed character */
273 if ( iptr
+ 1 >= iend
)
276 break; /* No next character */
279 unsigned char c2
= iptr
[1];
280 if ( c2
< 0x40 || c2
>= 0x80 ||
281 !(ch
= to_ucs4_comb
[c1
- 0xc1][c2
- 0x40]) )
284 break; /* Illegal combination */
301 optr
[1] = 0x80 | (ch
& 0x3f);
302 optr
[0] = 0xc0 | (ch
>> 6);
307 optr
[2] = 0x80 | (ch
& 0x3f);
309 optr
[1] = 0x80 | (ch
& 0x3f);
310 optr
[0] = 0xe0 | (ch
>> 6);
317 *inbytesleft
= iend
- iptr
;
318 *outbytesleft
= oend
- optr
;
331 /*****************************************************************************
333 *****************************************************************************/
334 vlc_iconv_t
vlc_iconv_open( const char *tocode
, const char *fromcode
)
337 if( !strcasecmp(tocode
, "UTF-8") && !strcasecmp(fromcode
, "ISO_6937") )
338 return (vlc_iconv_t
)(-2);
340 #if defined(HAVE_ICONV)
341 # if defined(__OS2__) && defined(__INNOTEK_LIBC__)
342 char tocode_ucs2
[] = "UCS-2LE";
343 char fromcode_ucs2
[] = "UCS-2LE";
344 os2_iconv_t
*p_os2_iconv
;
346 /* Workaround for UTF-16 because OS/2 supports UCS-2 only not UTF-16 */
347 if( !strncmp( tocode
, "UTF-16", 6 ))
349 strncpy( tocode_ucs2
+ 5, tocode
+ 6, 2 );
350 tocode
= tocode_ucs2
;
353 if( !strncmp( fromcode
, "UTF-16", 6 ))
355 strncpy( fromcode_ucs2
+ 5, fromcode
+ 6, 2 );
356 fromcode
= fromcode_ucs2
;
359 p_os2_iconv
= ( os2_iconv_t
* )iconv_open( tocode
, fromcode
);
361 if( p_os2_iconv
!= ( iconv_t
)(-1))
363 /* Mimic a behavior of GNU libiconv */
364 uconv_attribute_t attr
;
366 UniQueryUconvObject( p_os2_iconv
->from
, &attr
,
367 sizeof( uconv_attribute_t
),
369 attr
.converttype
|= CVTTYPE_PATH
;
370 UniSetUconvObject( p_os2_iconv
->from
, &attr
);
373 return ( vlc_iconv_t
)p_os2_iconv
;
375 return iconv_open( tocode
, fromcode
);
378 return (vlc_iconv_t
)(-1);
382 size_t vlc_iconv( vlc_iconv_t cd
, const char **inbuf
, size_t *inbytesleft
,
383 char **outbuf
, size_t *outbytesleft
)
388 if ( cd
== (vlc_iconv_t
)(-2) )
390 unsigned char *out
= (unsigned char *)*outbuf
;
392 ret
= ISO6937toUTF8( inbuf
, inbytesleft
, &out
, outbytesleft
);
393 *outbuf
= (char *)out
;
397 #if defined(HAVE_ICONV)
399 ICONV_CONST
char *cin
= (ICONV_CONST
char *)*inbuf
;
401 ret
= iconv( cd
, &cin
, inbytesleft
, outbuf
, outbytesleft
);
410 int vlc_iconv_close( vlc_iconv_t cd
)
413 if ( cd
== (vlc_iconv_t
)(-2) )
416 #if defined(HAVE_ICONV)
417 return iconv_close( cd
);
423 /*****************************************************************************
425 * (adapted from libavcodec, author Michael Niedermayer <michaelni@gmx.at>)
426 *****************************************************************************/
427 bool vlc_ureduce( unsigned *pi_dst_nom
, unsigned *pi_dst_den
,
428 uint64_t i_nom
, uint64_t i_den
, uint64_t i_max
)
440 i_gcd
= GCD( i_nom
, i_den
);
444 if( i_max
== 0 ) i_max
= INT64_C(0xFFFFFFFF);
446 if( i_nom
> i_max
|| i_den
> i_max
)
448 uint64_t i_a0_num
= 0, i_a0_den
= 1, i_a1_num
= 1, i_a1_den
= 0;
453 uint64_t i_x
= i_nom
/ i_den
;
454 uint64_t i_a2n
= i_x
* i_a1_num
+ i_a0_num
;
455 uint64_t i_a2d
= i_x
* i_a1_den
+ i_a0_den
;
457 if( i_a2n
> i_max
|| i_a2d
> i_max
) break;
461 i_a0_num
= i_a1_num
; i_a0_den
= i_a1_den
;
462 i_a1_num
= i_a2n
; i_a1_den
= i_a2d
;
463 if( i_nom
== 0 ) break;
464 i_x
= i_nom
; i_nom
= i_den
; i_den
= i_x
;