163 lines
3.7 KiB
C
163 lines
3.7 KiB
C
/* Modified (m) 2017 Thomas Wolff: revise Unicode and locale/wchar handling */
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#include <_ansi.h>
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#include <wctype.h>
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#include <stdint.h>
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//#include <errno.h>
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#include "local.h"
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/*
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struct caseconv_entry describes the case conversion behaviour
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of a range of Unicode characters.
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It was designed to be compact for a minimal table size.
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The range is first...first + diff.
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Conversion behaviour for a character c in the respective range:
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mode == TOLO towlower (c) = c + delta
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mode == TOUP towupper (c) = c + delta
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mode == TOBOTH (titling case characters)
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towlower (c) = c + 1
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towupper (c) = c - 1
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mode == TO1 capital/small letters are alternating
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delta == EVENCAP even codes are capital
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delta == ODDCAP odd codes are capital
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(this correlates with an even/odd first range value
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as of Unicode 10.0 but we do not rely on this)
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As of Unicode 10.0, the following field lengths are sufficient
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first: 17 bits
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diff: 8 bits
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delta: 17 bits
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mode: 2 bits
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The reserve of 4 bits (to limit the struct to 6 bytes)
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is currently added to the 'first' field;
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should a future Unicode version make it necessary to expand the others,
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the 'first' field could be reduced as needed, or larger ranges could
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be split up (reduce limit max=255 e.g. to max=127 or max=63 in
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script mkcaseconv, check increasing table size).
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*/
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enum {TO1, TOLO, TOUP, TOBOTH};
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enum {EVENCAP, ODDCAP};
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static struct caseconv_entry {
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uint_least32_t first: 21;
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uint_least32_t diff: 8;
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uint_least32_t mode: 2;
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int_least32_t delta: 17;
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} __attribute__ ((packed))
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caseconv_table [] = {
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#include "caseconv.t"
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};
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#define first(ce) ce.first
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#define last(ce) (ce.first + ce.diff)
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/* auxiliary function for binary search in interval properties table */
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static const struct caseconv_entry *
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bisearch (wint_t ucs, const struct caseconv_entry *table, int max)
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{
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int min = 0;
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int mid;
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if (ucs < first(table[0]) || ucs > last(table[max]))
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return 0;
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while (max >= min)
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{
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mid = (min + max) / 2;
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if (ucs > last(table[mid]))
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min = mid + 1;
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else if (ucs < first(table[mid]))
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max = mid - 1;
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else
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return &table[mid];
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}
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return 0;
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}
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static wint_t
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toulower (wint_t c)
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{
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const struct caseconv_entry * cce =
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bisearch(c, caseconv_table,
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sizeof(caseconv_table) / sizeof(*caseconv_table) - 1);
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if (cce)
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switch (cce->mode)
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{
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case TOLO:
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return c + cce->delta;
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case TOBOTH:
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return c + 1;
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case TO1:
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switch (cce->delta)
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{
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case EVENCAP:
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if (!(c & 1))
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return c + 1;
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break;
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case ODDCAP:
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if (c & 1)
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return c + 1;
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break;
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default:
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break;
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}
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default:
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break;
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}
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return c;
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}
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static wint_t
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touupper (wint_t c)
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{
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const struct caseconv_entry * cce =
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bisearch(c, caseconv_table,
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sizeof(caseconv_table) / sizeof(*caseconv_table) - 1);
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if (cce)
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switch (cce->mode)
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{
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case TOUP:
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return c + cce->delta;
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case TOBOTH:
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return c - 1;
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case TO1:
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switch (cce->delta)
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{
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case EVENCAP:
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if (c & 1)
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return c - 1;
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break;
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case ODDCAP:
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if (!(c & 1))
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return c - 1;
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break;
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default:
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break;
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}
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default:
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break;
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}
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return c;
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}
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wint_t
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towctrans_l (wint_t c, wctrans_t w, struct __locale_t *locale)
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{
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wint_t u = _jp2uc_l (c, locale);
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wint_t res;
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if (w == WCT_TOLOWER)
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res = toulower (u);
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else if (w == WCT_TOUPPER)
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res = touupper (u);
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else
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{
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// skipping the errno setting that was previously involved
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// by delegating to towctrans; it was causing trouble (cygwin crash)
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// and there is no errno specified for towctrans
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return c;
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}
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if (res != u)
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return _uc2jp_l (res, locale);
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else
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return c;
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}
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