diff options
Diffstat (limited to 'libraries/liblunicode/ucdata/format.txt')
| -rw-r--r-- | libraries/liblunicode/ucdata/format.txt | 267 |
1 files changed, 267 insertions, 0 deletions
diff --git a/libraries/liblunicode/ucdata/format.txt b/libraries/liblunicode/ucdata/format.txt new file mode 100644 index 0000000..e285b39 --- /dev/null +++ b/libraries/liblunicode/ucdata/format.txt @@ -0,0 +1,267 @@ +# +# $Id: format.txt,v 1.2 2001/01/02 18:46:20 mleisher Exp $ +# + +CHARACTER DATA +============== + +This package generates some data files that contain character properties useful +for text processing. + +CHARACTER PROPERTIES +==================== + +The first data file is called "ctype.dat" and contains a compressed form of +the character properties found in the Unicode Character Database (UCDB). +Additional properties can be specified in limited UCDB format in another file +to avoid modifying the original UCDB. + +The following is a property name and code table to be used with the character +data: + +NAME CODE DESCRIPTION +--------------------- +Mn 0 Mark, Non-Spacing +Mc 1 Mark, Spacing Combining +Me 2 Mark, Enclosing +Nd 3 Number, Decimal Digit +Nl 4 Number, Letter +No 5 Number, Other +Zs 6 Separator, Space +Zl 7 Separator, Line +Zp 8 Separator, Paragraph +Cc 9 Other, Control +Cf 10 Other, Format +Cs 11 Other, Surrogate +Co 12 Other, Private Use +Cn 13 Other, Not Assigned +Lu 14 Letter, Uppercase +Ll 15 Letter, Lowercase +Lt 16 Letter, Titlecase +Lm 17 Letter, Modifier +Lo 18 Letter, Other +Pc 19 Punctuation, Connector +Pd 20 Punctuation, Dash +Ps 21 Punctuation, Open +Pe 22 Punctuation, Close +Po 23 Punctuation, Other +Sm 24 Symbol, Math +Sc 25 Symbol, Currency +Sk 26 Symbol, Modifier +So 27 Symbol, Other +L 28 Left-To-Right +R 29 Right-To-Left +EN 30 European Number +ES 31 European Number Separator +ET 32 European Number Terminator +AN 33 Arabic Number +CS 34 Common Number Separator +B 35 Block Separator +S 36 Segment Separator +WS 37 Whitespace +ON 38 Other Neutrals +Pi 47 Punctuation, Initial +Pf 48 Punctuation, Final +# +# Implementation specific properties. +# +Cm 39 Composite +Nb 40 Non-Breaking +Sy 41 Symmetric (characters which are part of open/close pairs) +Hd 42 Hex Digit +Qm 43 Quote Mark +Mr 44 Mirroring +Ss 45 Space, Other (controls viewed as spaces in ctype isspace()) +Cp 46 Defined character + +The actual binary data is formatted as follows: + + Assumptions: unsigned short is at least 16-bits in size and unsigned long + is at least 32-bits in size. + + unsigned short ByteOrderMark + unsigned short OffsetArraySize + unsigned long Bytes + unsigned short Offsets[OffsetArraySize + 1] + unsigned long Ranges[N], N = value of Offsets[OffsetArraySize] + + The Bytes field provides the total byte count used for the Offsets[] and + Ranges[] arrays. The Offsets[] array is aligned on a 4-byte boundary and + there is always one extra node on the end to hold the final index of the + Ranges[] array. The Ranges[] array contains pairs of 4-byte values + representing a range of Unicode characters. The pairs are arranged in + increasing order by the first character code in the range. + + Determining if a particular character is in the property list requires a + simple binary search to determine if a character is in any of the ranges + for the property. + + If the ByteOrderMark is equal to 0xFFFE, then the data was generated on a + machine with a different endian order and the values must be byte-swapped. + + To swap a 16-bit value: + c = (c >> 8) | ((c & 0xff) << 8) + + To swap a 32-bit value: + c = ((c & 0xff) << 24) | (((c >> 8) & 0xff) << 16) | + (((c >> 16) & 0xff) << 8) | (c >> 24) + +CASE MAPPINGS +============= + +The next data file is called "case.dat" and contains three case mapping tables +in the following order: upper, lower, and title case. Each table is in +increasing order by character code and each mapping contains 3 unsigned longs +which represent the possible mappings. + +The format for the binary form of these tables is: + + unsigned short ByteOrderMark + unsigned short NumMappingNodes, count of all mapping nodes + unsigned short CaseTableSizes[2], upper and lower mapping node counts + unsigned long CaseTables[NumMappingNodes] + + The starting indexes of the case tables are calculated as following: + + UpperIndex = 0; + LowerIndex = CaseTableSizes[0] * 3; + TitleIndex = LowerIndex + CaseTableSizes[1] * 3; + + The order of the fields for the three tables are: + + Upper case + ---------- + unsigned long upper; + unsigned long lower; + unsigned long title; + + Lower case + ---------- + unsigned long lower; + unsigned long upper; + unsigned long title; + + Title case + ---------- + unsigned long title; + unsigned long upper; + unsigned long lower; + + If the ByteOrderMark is equal to 0xFFFE, endian swapping is required in the + same way as described in the CHARACTER PROPERTIES section. + + Because the tables are in increasing order by character code, locating a + mapping requires a simple binary search on one of the 3 codes that make up + each node. + + It is important to note that there can only be 65536 mapping nodes which + divided into 3 portions allows 21845 nodes for each case mapping table. The + distribution of mappings may be more or less than 21845 per table, but only + 65536 are allowed. + +COMPOSITIONS +============ + +This data file is called "comp.dat" and contains data that tracks character +pairs that have a single Unicode value representing the combination of the two +characters. + +The format for the binary form of this table is: + + unsigned short ByteOrderMark + unsigned short NumCompositionNodes, count of composition nodes + unsigned long Bytes, total number of bytes used for composition nodes + unsigned long CompositionNodes[NumCompositionNodes * 4] + + If the ByteOrderMark is equal to 0xFFFE, endian swapping is required in the + same way as described in the CHARACTER PROPERTIES section. + + The CompositionNodes[] array consists of groups of 4 unsigned longs. The + first of these is the character code representing the combination of two + other character codes, the second records the number of character codes that + make up the composition (not currently used), and the last two are the pair + of character codes whose combination is represented by the character code in + the first field. + +DECOMPOSITIONS +============== + +The next data file is called "decomp.dat" and contains the decomposition data +for all characters with decompositions containing more than one character and +are *not* compatibility decompositions. Compatibility decompositions are +signaled in the UCDB format by the use of the <compat> tag in the +decomposition field. Each list of character codes represents a full +decomposition of a composite character. The nodes are arranged in increasing +order by character code. + +The format for the binary form of this table is: + + unsigned short ByteOrderMark + unsigned short NumDecompNodes, count of all decomposition nodes + unsigned long Bytes + unsigned long DecompNodes[(NumDecompNodes * 2) + 1] + unsigned long Decomp[N], N = sum of all counts in DecompNodes[] + + If the ByteOrderMark is equal to 0xFFFE, endian swapping is required in the + same way as described in the CHARACTER PROPERTIES section. + + The DecompNodes[] array consists of pairs of unsigned longs, the first of + which is the character code and the second is the initial index of the list + of character codes representing the decomposition. + + Locating the decomposition of a composite character requires a binary search + for a character code in the DecompNodes[] array and using its index to + locate the start of the decomposition. The length of the decomposition list + is the index in the following element in DecompNode[] minus the current + index. + +COMBINING CLASSES +================= + +The fourth data file is called "cmbcl.dat" and contains the characters with +non-zero combining classes. + +The format for the binary form of this table is: + + unsigned short ByteOrderMark + unsigned short NumCCLNodes + unsigned long Bytes + unsigned long CCLNodes[NumCCLNodes * 3] + + If the ByteOrderMark is equal to 0xFFFE, endian swapping is required in the + same way as described in the CHARACTER PROPERTIES section. + + The CCLNodes[] array consists of groups of three unsigned longs. The first + and second are the beginning and ending of a range and the third is the + combining class of that range. + + If a character is not found in this table, then the combining class is + assumed to be 0. + + It is important to note that only 65536 distinct ranges plus combining class + can be specified because the NumCCLNodes is usually a 16-bit number. + +NUMBER TABLE +============ + +The final data file is called "num.dat" and contains the characters that have +a numeric value associated with them. + +The format for the binary form of the table is: + + unsigned short ByteOrderMark + unsigned short NumNumberNodes + unsigned long Bytes + unsigned long NumberNodes[NumNumberNodes] + unsigned short ValueNodes[(Bytes - (NumNumberNodes * sizeof(unsigned long))) + / sizeof(short)] + + If the ByteOrderMark is equal to 0xFFFE, endian swapping is required in the + same way as described in the CHARACTER PROPERTIES section. + + The NumberNodes array contains pairs of values, the first of which is the + character code and the second an index into the ValueNodes array. The + ValueNodes array contains pairs of integers which represent the numerator + and denominator of the numeric value of the character. If the character + happens to map to an integer, both the values in ValueNodes will be the + same. |