diff options
| -rw-r--r-- | newlib/libc/ctype/towctrans_l.c | 36 |
1 files changed, 33 insertions, 3 deletions
diff --git a/newlib/libc/ctype/towctrans_l.c b/newlib/libc/ctype/towctrans_l.c index ca7e89f88..9759cf7bc 100644 --- a/newlib/libc/ctype/towctrans_l.c +++ b/newlib/libc/ctype/towctrans_l.c @@ -4,8 +4,36 @@ //#include <errno.h> #include "local.h" -enum {EVENCAP, ODDCAP}; +/* + struct caseconv_entry describes the case conversion behaviour + of a range of Unicode characters. + It was designed to be compact for a minimal table size. + The range is first...first + diff. + Conversion behaviour for a character c in the respective range: + mode == TOLO towlower (c) = c + delta + mode == TOUP towupper (c) = c + delta + mode == TOBOTH (titling case characters) + towlower (c) = c + 1 + towupper (c) = c - 1 + mode == TO1 capital/small letters are alternating + delta == EVENCAP even codes are capital + delta == ODDCAP odd codes are capital + (this correlates with an even/odd first range value + as of Unicode 10.0 but we do not rely on this) + As of Unicode 10.0, the following field lengths are sufficient + first: 17 bits + diff: 8 bits + delta: 17 bits + mode: 2 bits + The reserve of 4 bits (to limit the struct to 6 bytes) + is currently added to the 'first' field; + should a future Unicode version make it necessary to expand the others, + the 'first' field could be reduced as needed, or larger ranges could + be split up (reduce limit max=255 e.g. to max=127 or max=63 in + script mkcaseconv, check increasing table size). + */ enum {TO1, TOLO, TOUP, TOBOTH}; +enum {EVENCAP, ODDCAP}; static struct caseconv_entry { unsigned int first: 21; unsigned short diff: 8; @@ -71,6 +99,7 @@ toulower (wint_t c) default: break; } + return c; } @@ -102,9 +131,10 @@ touupper (wint_t c) default: break; } - default: - break; + default: + break; } + return c; } |