/*====================================================================
 *
 * TXF file buffering module
 *
 *====================================================================
 *                                   copyright(C) 1992-1994 T.Nakatani
 *====================================================================
 */
#include "txf.h"
char far *buf_base;
char far *bufrp;
long int bufremain, bufyet, bufldval, bufoffset, buffsize;

char far *buffileopen(int i)
{
	char *tmpinname, *tmpoutname;
	struct stat sbuf;
	int rd;

	tmpinname = ((tmpinfile == -1) ? inputfile : tfile[tmpinfile]);
	tmpoutname = tfile[((tmpinfile > 0) ? 0 : 1)];
	if (stat(tmpinname, &sbuf) == 0) {
		buffsize = fsize = sbuf.st_size;
	}
	else {
		buffsize = fsize = 0;
	}

	if (*tmpinname != NUL) {
		inputh = open(tmpinname, O_RDONLY | O_BINARY);
	}
	else {
		errexit("Cannot open inputfile.");
	}
	outputh = open(tmpoutname, O_WRONLY | O_BINARY | O_CREAT | O_TRUNC, S_IWRITE);
#ifdef DEBUG
	if (viewmode > 2) {
		fprintf(stderr, "Info:read=%s(%d),write=%s(%d),tmpinfile=%d\n",
			tmpinname, inputh, tmpoutname, outputh, tmpinfile);
	}
#endif
	if ((inputh == -1) || (outputh == -1)) {
		fprintf(stderr, "Error:cannot open TMP file(%d)\n", i);
#ifdef DEBUG
		fprintf(stderr, "Info:read=%s(%d),write=%s(%d)\n",
			tmpinname, inputh, tmpoutname, outputh);
#endif
		exit(1);
	}
	if ((buf_base = farmalloc(rbufsize+2)) == NULL) {
		rbufsize /= 2;
		if ((buf_base = farmalloc(rbufsize+2)) == NULL) {
			errexit("out of memory.");
		}
	}
	bufremain = bufyet = buffsize;
	bufldval = min(rbufsize-1, bufyet);
	bufoffset = 0;
	if (_dos_read(inputh, buf_base, bufldval, &rd) != 0) {
		errexit("read error");
	}
	bufyet -= rd;
	bufrp = NULL;
	return (buf_base);
}

char far *readnext(int val)
{
	unsigned int rd;
	if (bufrp == NULL) {
		bufrp = buf_base;
		if (val > 1) {
			bufrp += (long)val-1;
		}
		bufremain -= val;
	}
	else {
		bufrp += (long)val;
		bufoffset += val;
		bufremain -= val;
		if ((bufoffset > rbufsize-2048) && (bufyet > 0)) {
			far_memcpy(buf_base, buf_base+(long)(rbufsize-4096), 4095);
			bufldval = min(rbufsize-4096, bufyet);
			if (_dos_read(inputh, buf_base+(long)4095, bufldval, &rd) != 0) {
				errexit("read error");
			}
			bufyet -= rd;
			bufoffset -= rbufsize-4096;
			bufrp = buf_base + (long)bufoffset;
		}
	}
	return (bufrp);
}
#if 0
char *readbefore(int val)
{
	bufrp -= val;
	bufoffset -= val;
	bufremain += val;
	if (bufoffset < 0) {
		if (fseek(input, -(rbufsize>>1), SEEK_CUR) != 0) {
			fseek(input, 0, SEEK_SET);
			bufyet = buffsize;
			bufldval = min(rbufsize-1, bufyet);
			bufyet -= (unsigned long)fread(buf_base, 1, bufldval, input);
			bufoffset = buffsize - bufremain;
			bufrp = buf_base + bufoffset;
		}
		else {
			bufyet += ((rbufsize>>1)+bufldval);
			bufldval = min(rbufsize-1, bufyet);
			bufyet -= fread(buf_base, 1, bufldval, input);
			bufoffset += (rbufsize>>1);
			bufrp = buf_base + bufoffset;
		}
	}
	return (bufrp);
}
#endif

long int remainbyte()
{
	return ((bufremain < 0) ? 0 : bufremain);
}

void bufclose()
{
	close(inputh);
	close(outputh);
	farfree(buf_base);
	tmpinfile = ((tmpinfile > 0) ? 0 : 1);
#ifdef DEBUG
	if (viewmode > 2) {
		fprintf(stderr, "Info:tmpinfile = %d\n",tmpinfile);
	}
#endif
}

int chktouch(char far *rptr, int iy)
{
	if (ishflg) {
		if (ishchk(rptr) > 0) return (1);
	}
	if (quoteflg) {
		if (quotechk(rptr)) {
			return (1);
		}
	}
	if (levelchk(iy)) {
		return (1);
	}
	return (0);
}