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| author | Karl Williamson <khw@cpan.org> | 2021-06-14 12:32:41 -0600 |
|---|---|---|
| committer | Karl Williamson <khw@cpan.org> | 2021-08-07 05:14:43 -0600 |
| commit | fcd03d925b4b3a67a6162b516b3ea4194e92bc92 (patch) | |
| tree | c3fceba9a87467207809454f8bb38f6cb8455855 /utf8.h | |
| parent | 36da1e17a35eb23f0d666ee29dbff5c7823cad4c (diff) | |
| download | perl-fcd03d925b4b3a67a6162b516b3ea4194e92bc92.tar.gz | |
utf8.h: Make a bit of EBCDIC known to ASCII
This info is needed in one other place; doing it here means only
specifying it once.
Diffstat (limited to 'utf8.h')
| -rw-r--r-- | utf8.h | 19 |
1 files changed, 15 insertions, 4 deletions
@@ -78,6 +78,15 @@ the string is invariant. #define FOLDEQ_S1_FOLDS_SANE (1 << 4) #define FOLDEQ_S2_FOLDS_SANE (1 << 5) +/* This will be described more fully below, but it turns out that the + * fundamental difference between UTF-8 and UTF-EBCDIC is that the former has + * the upper 2 bits of a continuation byte be '10', and the latter has the + * upper 3 bits be '101', leaving 6 and 5 significant bits respectively. + * + * It is helpful to know the EBCDIC value on ASCII platforms, mainly to avoid + * some #ifdef's */ +#define UTF_EBCDIC_CONTINUATION_BYTE_INFO_BITS 5 + #ifdef EBCDIC /* The equivalent of these macros but implementing UTF-EBCDIC are in the following header file: @@ -287,7 +296,8 @@ are in the character. */ /* This defines the bits that are to be in the continuation bytes of a * multi-byte UTF-8 encoded character that mark it is a continuation byte. * This turns out to be 0x80 in UTF-8, 0xA0 in UTF-EBCDIC. (khw doesn't know - * the underlying reason that B0 works here) */ + * the underlying reason that B0 works here, except it just happens to work. + * One could solve for two linear equations and come up with it.) */ #define UTF_CONTINUATION_MARK (UTF_IS_CONTINUATION_MASK & 0xB0) /* Is the byte 'c' part of a multi-byte UTF8-8 encoded sequence, and not the @@ -439,9 +449,10 @@ encoded as UTF-8. C<cp> is a native (ASCII or EBCDIC) code point if less than #define MAX_UTF8_TWO_BYTE (32 * (1U << UTF_ACCUMULATION_SHIFT) - 1) /* The largest code point representable by two UTF-8 bytes on any platform that - * Perl runs on. This value is constrained by EBCDIC which has 5 bits per - * continuation byte */ -#define MAX_PORTABLE_UTF8_TWO_BYTE (32 * nBIT_UMAX(5)) + * Perl runs on. */ +#define MAX_PORTABLE_UTF8_TWO_BYTE \ + nBIT_UMAX(5 + MIN( UTF_CONTINUATION_BYTE_INFO_BITS, \ + UTF_EBCDIC_CONTINUATION_BYTE_INFO_BITS)) /* |