Commit 85eeac93 authored by Chong Yidong's avatar Chong Yidong

Consistently hex notation to represent character codes.

* nonascii.texi (Text Representations, Character Codes)
(Converting Representations, Explicit Encoding)
(Translation of Characters): Use hex notation consistently.
(Character Sets): Fix map-charset-chars doc (Bug#5197).
parent b894c439
2010-01-02 Chong Yidong <cyd@stupidchicken.com>
* nonascii.texi (Text Representations, Character Codes)
(Converting Representations, Explicit Encoding)
(Translation of Characters): Use hex notation consistently.
(Character Sets): Fix map-charset-chars doc (Bug#5197).
2010-01-01 Chong Yidong <cyd@stupidchicken.com>
* loading.texi (Where Defined): Make it clearer that these are
......
......@@ -46,12 +46,12 @@ in most any known written language.
follows the @dfn{Unicode Standard}. The Unicode Standard assigns a
unique number, called a @dfn{codepoint}, to each and every character.
The range of codepoints defined by Unicode, or the Unicode
@dfn{codespace}, is @code{0..10FFFF} (in hex), inclusive. Emacs
extends this range with codepoints in the range @code{110000..3FFFFF},
which it uses for representing characters that are not unified with
Unicode and raw 8-bit bytes that cannot be interpreted as characters
(the latter occupy the range @code{3FFF80..3FFFFF}). Thus, a
character codepoint in Emacs is a 22-bit integer number.
@dfn{codespace}, is @code{0..#x10FFFF} (in hexadecimal notation),
inclusive. Emacs extends this range with codepoints in the range
@code{#x110000..#x3FFFFF}, which it uses for representing characters
that are not unified with Unicode and @dfn{raw 8-bit bytes} that
cannot be interpreted as characters. Thus, a character codepoint in
Emacs is a 22-bit integer number.
@cindex internal representation of characters
@cindex characters, representation in buffers and strings
......@@ -189,8 +189,8 @@ of characters as @var{string}. If @var{string} is a multibyte string,
it is returned unchanged. The function assumes that @var{string}
includes only @acronym{ASCII} characters and raw 8-bit bytes; the
latter are converted to their multibyte representation corresponding
to the codepoints in the @code{3FFF80..3FFFFF} area (@pxref{Text
Representations, codepoints}).
to the codepoints @code{#x3FFF80} through @code{#x3FFFFF}, inclusive
(@pxref{Text Representations, codepoints}).
@end defun
@defun string-to-unibyte string
......@@ -271,15 +271,19 @@ contains no text properties.
The unibyte and multibyte text representations use different
character codes. The valid character codes for unibyte representation
range from 0 to 255---the values that can fit in one byte. The valid
character codes for multibyte representation range from 0 to 4194303
(#x3FFFFF). In this code space, values 0 through 127 are for
@acronym{ASCII} characters, and values 128 through 4194175 (#x3FFF7F)
are for non-@acronym{ASCII} characters. Values 0 through 1114111
(#10FFFF) correspond to Unicode characters of the same codepoint;
values 1114112 (#110000) through 4194175 (#x3FFF7F) represent
characters that are not unified with Unicode; and values 4194176
(#x3FFF80) through 4194303 (#x3FFFFF) represent eight-bit raw bytes.
range from 0 to @code{#xFF} (255)---the values that can fit in one
byte. The valid character codes for multibyte representation range
from 0 to @code{#x3FFFFF}. In this code space, values 0 through
@code{#x7F} (127) are for @acronym{ASCII} characters, and values
@code{#x80} (128) through @code{#x3FFF7F} (4194175) are for
non-@acronym{ASCII} characters.
Emacs character codes are a superset of the Unicode standard.
Values 0 through @code{#x10FFFF} (1114111) correspond to Unicode
characters of the same codepoint; values @code{#x110000} (1114112)
through @code{#x3FFF7F} (4194175) represent characters that are not
unified with Unicode; and values @code{#x3FFF80} (4194176) through
@code{#x3FFFFF} (4194303) represent eight-bit raw bytes.
@defun characterp charcode
This returns @code{t} if @var{charcode} is a valid character, and
......@@ -540,7 +544,7 @@ and strings.
@cindex @code{eight-bit}, a charset
Emacs defines several special character sets. The character set
@code{unicode} includes all the characters whose Emacs code points are
in the range @code{0..10FFFF}. The character set @code{emacs}
in the range @code{0..#x10FFFF}. The character set @code{emacs}
includes all @acronym{ASCII} and non-@acronym{ASCII} characters.
Finally, the @code{eight-bit} charset includes the 8-bit raw bytes;
Emacs uses it to represent raw bytes encountered in text.
......@@ -628,12 +632,12 @@ that fits the second argument of @code{decode-char} above. If
The following function comes in handy for applying a certain
function to all or part of the characters in a charset:
@defun map-charset-chars function charset &optional arg from to
@defun map-charset-chars function charset &optional arg from-code to-code
Call @var{function} for characters in @var{charset}. @var{function}
is called with two arguments. The first one is a cons cell
@code{(@var{from} . @var{to})}, where @var{from} and @var{to}
indicate a range of characters contained in charset. The second
argument is the optional argument @var{arg}.
argument passed to @var{function} is @var{arg}.
By default, the range of codepoints passed to @var{function} includes
all the characters in @var{charset}, but optional arguments
......@@ -751,7 +755,7 @@ This variable automatically becomes buffer-local when set.
@defun make-translation-table-from-vector vec
This function returns a translation table made from @var{vec} that is
an array of 256 elements to map byte values 0 through 255 to
an array of 256 elements to map bytes (values 0 through #xFF) to
characters. Elements may be @code{nil} for untranslated bytes. The
returned table has a translation table for reverse mapping in the
first extra slot, and the value @code{1} in the second extra slot.
......@@ -1562,10 +1566,10 @@ in this section.
text. They logically consist of a series of byte values; that is, a
series of @acronym{ASCII} and eight-bit characters. In unibyte
buffers and strings, these characters have codes in the range 0
through 255. In a multibyte buffer or string, eight-bit characters
have character codes higher than 255 (@pxref{Text Representations}),
but Emacs transparently converts them to their single-byte values when
you encode or decode such text.
through #xFF (255). In a multibyte buffer or string, eight-bit
characters have character codes higher than #xFF (@pxref{Text
Representations}), but Emacs transparently converts them to their
single-byte values when you encode or decode such text.
The usual way to read a file into a buffer as a sequence of bytes, so
you can decode the contents explicitly, is with
......
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