NAME

_XConvertCTToWC − conversion from  CT string to  WC string

SYNOPSIS

int _XConvertCTToWC(xlocale, ct_str, ct_bytes, wc_str, wc_len,
scanned_bytes, state)
XLocale xlocale;
char *ct_str;
int ct_bytes;
wchar *wc_str;
int *wc_len;
int *scanned_bytes;
_State *state;

ARGUMENTS

xlocaleIn: specifies locale, the default NULL is the current locale. 

ct_strIn: CT string. 

ct_bytesIn: length of CT strings, counted in bytes. 

wc_strOut: conversion buffer of result wchar string. 

wc_lenIn/Out: as "In" it is length of buffer wc_str passed by caller; as "Out" it is the returned number of converted wchars. 

scanned_bytes
Number of CT bytes converted when the function returns.

stateIn/Out: as "In" it is the state at the beginning of the CT string; as "Out" it is the current state stopped at last converted CT encoding.  The state is defined internally by Xlib.  If this pointer is null, the function will assume the state to be the default CT state. Of course, nothing will be put in the null pointer. Do not modify or free this data. 

DESCRIPTION

The _XConvertCTToWC converts the string encoded in CT to string encoded in wchar.  After a successful conversion, the null character WNULL will be appended to wc_str if there is room for it in the buffer.  The terminator WNULL of wchar string is not counted in length of output buffer wc_len. 

The returned state will point to a state of the encoding in the internal table, so do not modify or free this pointer. 

When function returns at any time, scanned_bytes always remembers where stopped, and state always remembers the current CT state if it is not null pointer. 

The caller of this function has to provide the output buffer wc_str, and store the buffer length(in wchars) into wc_len as input.  By using scanned_bytes and state, the caller can break a large CT string into pieces, and convert one piece at a time. 

In other hand caller can pass any broken CT string to this function for doing conversion.  For example, caller can still be trying of conversion when the error BadBuffer is occurred (output buffer was exhausted).  Usually, the application passes the NULL to state for first conversion as the following:

char *state = NULL;
_XConvertCTToWC(NULL, ct_str, ct_len, mb_str,
            &mb_len, &scanned, &state)

The conversion function returns the value of variable state to use for the conversion of the next unconverted piece of the same string.  And so on. 

If the value of state is invalid or null-pointer, the function will suppose the default state of CT as initial.  The default state of CT is defined in 3 cases of encoding:

1. no control sequence, GL and GR of Latin-1 is supposed. 

2. control sequence of Latin-1 GL only, GR of Latin-1 is supposed too. 

3. control sequence of Latin-1 GR only, GL of Latin-1 is supposed too. 

The function returns the BadBuffer meaning that the output buffer wc_str was exhausted.  The function returns the BadTerminate meaning that the CT string ct_str is terminated uncompletely, e.g., uncompleted ESC sequence or uncompleted code point ended at tail of ct_str. 

Only in both the case of BadBuffer and BadTerminate the caller can move pointer ct_str to (ct_str + *scanned_bytes), then continue to do conversion.  And function ensure that the wc_str stores the already converted wchar string; wc_len counts the number of them in wchars(not bytes); the state stores the last state of encoding. 

The function returns a number greater than zero meaning a number of wrong codepoints recovered by the function.  The wrong codepoint will be recovered with the first codepoint of the charset at which the wrong codepoint occurs.  After replaced, the function will continue to do conversion until one of the results Success, BadTerminate, BadBuffer or BadEncoding is met. 

The function returns BadEncoding meaning for unrecoverable wrong code which is actually wrong escape sequence, or not registered by system yet. 

Both the null character and ct_bytes will terminate the conversion. 

All error status are defined to be less than zero, i.e.:

#define Success          0

#define BadBuffer       -1

#define BadTerminate    -2

#define BadEncoding     -3

RETURNED VALUE

The _XConvertCTToWC will return the following values:

Success
successful conversion.

BadBuffer
output buffer(wc_str) was exhausted.

BadTerminate

BadEncoding
wrong codepoints can not be recovered.

> 0 number of wrong codepoints, but recovered. 

SEE ALSO

Refer to "CT and WC" for their definitions.