istlangch.c

T-kernel 的extension源代码

/*
 *----------------------------------------------------------------------
 *    T-Kernel / Standard Extension
 *
 *    Copyright (C) 2006 by Ken Sakamura. All rights reserved.
 *    T-Kernel / Standard Extension is distributed 
 *      under the T-License for T-Kernel / Standard Extension.
 *----------------------------------------------------------------------
 *
 *    Version:   1.00.00
 *    Released by T-Engine Forum(http://www.t-engine.org) at 2006/8/11.
 *
 *----------------------------------------------------------------------
 */

/*
 *	istlangch.c (libtcstr)
 */

#include <basic.h>
#include <tlang.h>

#define MAX_FE             128
#define TSD_ITH_VAL_2      2
#define TSD_ITH_MSK_0XFF00 (TC)0xff00
#define TSD_ITH_MAX_0XFD   (TC)0xfd
#define TSD_ITH_RTN_M1     (-1)
#define TSD_ITH_RTN_M2     (-2)
#define TSD_ITH_VAL_0XFEFE (TC)0xfefe
#define TSD_ITH_MSK_0XFF   (TC)0xff
#define TSD_ITH_CH_0XFE00  0xfe00U
#define TSD_ITH_CH_0X0000  0x0000U
#define TSD_ITH_MIN_0X21   (TC)0x21
#define TSD_ITH_MAX_0X7E   (TC)0x7e
#define TSD_ITH_MIN_0X80   (TC)0x80
#define TSD_ITH_SFT_MCR    ((UW)(nn-1) << 8)

/*
 * Determination of language (script) specification code
 *	Determine the language specification code characters one by one (in TC).
 * Return value	> 0	Language specification code (TLANG is returned)
 *		= 0	Not language specification code
 *		= -1	Invalid language specification code
 *		= -2	Indefinite language specification code (The code is not complete)
 *
 *	Initialize *n to "*n = 0" when calling it for the first time. Subsequently, call the returned
 *	value *n repeatedly without change to determine the language specification code.
 *
 *	(Ex. of use)
 *		n = 0;
 *		while ( (lang = isTLANGch(*tp++, &n)) == -2 );
 */
EXPORT W isTLANGch( TC ch, W *n )
{
	W	nn;

	if ( ch == TSD_ITH_VAL_0XFEFE ) {
		*n += TSD_ITH_VAL_2;
		return TSD_ITH_RTN_M2;
	}

	nn = *n;
	*n = 0;

	switch ( ch & TSD_ITH_MSK_0XFF00 ) {
	  case TSD_ITH_CH_0XFE00:
		nn++;
		ch &= TSD_ITH_MSK_0XFF;
		/* no break */

	  case TSD_ITH_CH_0X0000:
		if (( nn == 0 )||( nn > MAX_FE )) {
			break;
		}

		if ( ((ch >= TSD_ITH_MIN_0X21 )&&( ch <= TSD_ITH_MAX_0X7E))
		  || ((ch >= TSD_ITH_MIN_0X80 )&&( ch <= TSD_ITH_MAX_0XFD)) ) {
			/* Language specification code */
			return (W)(TSD_ITH_SFT_MCR | ch);
		}
		break;
	  default:
		/* nothing to do */
		break;
	}

	/* nn = 0 : Not language specification code
	   nn > 0 : Invalid language specification code */
	return ( nn == 0 )? 0: TSD_ITH_RTN_M1;
}