t6.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

	setsbits(c, n);
	setfbits(c, pts);	/* sneaky, CHARHT font bits are size bits */
	return(c);
}

Tchar t_setslant(void)		/* set slant from \S'...' */
{
	int n;
	Tchar c;

	getch();
	n = 0;
	n = inumb(&n);
	getch();
	if (nonumb)
		n = 0;
	c = SLANT;
	c |= ZBIT;
	setsfbits(c, n+180);
	return(c);
}


void caseft(void)
{
	if (!TROFF) {
		n_caseft();
		return;
	}
	skip();
	setfont(1);
}


void t_setfont(int a)
{
	int i, j;

	if (a)
		i = getrq();
	else 
		i = getsn();
	if (!i || i == 'P') {
		j = font1;
		goto s0;
	}
	if (/* i == 'S' || */ i == '0')	/* an experiment -- why can't we change to it? */
		return;
	if ((j = findft(i)) == -1)
		if ((j = setfp(0, i, (char*) 0, 1)) == -1)	/* try to put it in position 0 */
			return;
s0:
	font1 = font;
	font = j;
	mchbits();
}


void t_setwd(void)
{
	int base, wid;
	Tchar i;
	int delim, emsz, k;
	int savhp, savapts, savapts1, savfont, savfont1, savpts, savpts1;

	base = numtabp[ST].val = numtabp[SB].val = wid = numtabp[CT].val = 0;
	if (ismot(i = getch()))
		return;
	delim = cbits(i);
	savhp = numtabp[HP].val;
	numtabp[HP].val = 0;
	savapts = apts;
	savapts1 = apts1;
	savfont = font;
	savfont1 = font1;
	savpts = pts;
	savpts1 = pts1;
	setwdf++;
	while (cbits(i = getch()) != delim && !nlflg) {
		k = width(i);
		wid += k;
		numtabp[HP].val += k;
		if (!ismot(i)) {
			emsz = (INCH/72) * xpts;
		} else if (isvmot(i)) {
			k = absmot(i);
			if (isnmot(i))
				k = -k;
			base -= k;
			emsz = 0;
		} else 
			continue;
		if (base < numtabp[SB].val)
			numtabp[SB].val = base;
		if ((k = base + emsz) > numtabp[ST].val)
			numtabp[ST].val = k;
	}
	setn1(wid, 0, (Tchar) 0);
	numtabp[HP].val = savhp;
	apts = savapts;
	apts1 = savapts1;
	font = savfont;
	font1 = savfont1;
	pts = savpts;
	pts1 = savpts1;
	mchbits();
	setwdf = 0;
}


Tchar t_vmot(void)
{
	dfact = lss;
	vflag++;
	return t_mot();
}


Tchar t_hmot(void)
{
	dfact = EM;
	return t_mot();
}


Tchar t_mot(void)
{
	int j, n;
	Tchar i;

	j = HOR;
	getch(); /*eat delim*/
	if (n = atoi0()) {
		if (vflag)
			j = VERT;
		i = makem(quant(n, j));
	} else
		i = 0;
	getch();
	vflag = 0;
	dfact = 1;
	return(i);
}


Tchar t_sethl(int k)
{
	int j;
	Tchar i;

	j = EM / 2;
	if (k == 'u')
		j = -j;
	else if (k == 'r')
		j = -2 * j;
	vflag++;
	i = makem(j);
	vflag = 0;
	return(i);
}


Tchar t_makem(int i)
{
	Tchar j;

	if (i >= 0)
		j = i;
	else
		j = -i;
	if (Hor > 1 && !vflag)
		j = (j + Hor/2)/Hor * Hor;
	j |= MOT;
	if (i < 0)
		j |= NMOT;
	if (vflag)
		j |= VMOT;
	return(j);
}


Tchar getlg(Tchar i)
{
	Tchar j, k;
	int lf;

	if (!TROFF)
		return i;
	if ((lf = fonts[fbits(i)].ligfont) == 0) /* font lacks ligatures */
		return(i);
	j = getch0();
	if (cbits(j) == 'i' && (lf & LFI))
		j = LIG_FI;
	else if (cbits(j) == 'l' && (lf & LFL))
		j = LIG_FL;
	else if (cbits(j) == 'f' && (lf & LFF)) {
		if ((lf & (LFFI|LFFL)) && lg != 2) {
			k = getch0();
			if (cbits(k)=='i' && (lf&LFFI))
				j = LIG_FFI;
			else if (cbits(k)=='l' && (lf&LFFL))
				j = LIG_FFL;
			else {
				*pbp++ = k;
				j = LIG_FF;
			}
		} else 
			j = LIG_FF;
	} else {
		*pbp++ = j;
		j = i;
	}
	return(i & SFMASK | j);
}


void caselg(void)
{

	if(TROFF) {
		skip();
		lg = atoi0();
		if (nonumb)
			lg = 1;
	}
}

void casefp(void)
{
	int i, j;

	if (!TROFF) {
		n_casefp();
		return;
	}
	skip();
	i = cbits(getch());
	if (isdigit(i)) {
		i -= '0';
		j = cbits(getch());
		if (isdigit(j))
			i = 10 * i + j - '0';
	}
	if (i <= 0 || i > nfonts)
		ERROR "fp: bad font position %d", i WARN;
	else if (skip() || !(j = getrq()))
		ERROR "fp: no font name" WARN; 
	else if (skip() || !getname())
		setfp(i, j, (char*) 0, 1);
	else		/* 3rd argument = filename */
		setfp(i, j, nextf, 1);
}

char *strdupl(const char *s)	/* make a copy of s */
{
	char *t;

	t = (char *) malloc(strlen(s) + 1);
	if (t == NULL)
		ERROR "out of space in strdupl(%s)", s FATAL;
	strcpy(t, s);
	return t;
}

setfp(int pos, int f, char *truename, int print)	/* mount font f at position pos[0...nfonts] */
{
	char pathname[NS], shortname[NS], *sl;

	zapwcache(0);
	if (truename)
		strcpy(shortname, truename);
	else
		strcpy(shortname, (char *) unpair(f));
	if (truename && strrchr(truename, '/')) {	/* .fp 1 R dir/file: use verbatim */
		sprintf(pathname, "%s", truename);
		if (fonts[pos].truename)
			free(fonts[pos].truename);
		fonts[pos].truename = strdupl(truename);
	} else if (truename) {			/* synonym: .fp 1 R Avant */
		sprintf(pathname, "%s/dev%s/%s", fontdir, devname, truename);
		truename = 0;	/* so doesn't get repeated by ptfpcmd */
	} else					/* vanilla: .fp 5 XX */
		sprintf(pathname, "%s/dev%s/%s", fontdir, devname, shortname);
	if (truename == 0 && fonts[pos].truename != 0) {
		free(fonts[pos].truename);
		fonts[pos].truename = 0;
	}
	if (getfont(pathname, pos) < 0) {
		ERROR "Can't open font file %s", pathname WARN;
		return -1;
	}
	if (print && !ascii) {
		ptfpcmd(pos, fonts[pos].longname, truename);
		ptfont();
	}
	if (pos == smnt) {
		smnt = 0; 
		sbold = 0; 
	}
	fontlab[pos] = f;
	if (smnt == 0 && fonts[pos].specfont)
		smnt = pos;
	bdtab[pos] = cstab[pos] = ccstab[pos] = 0;
	return pos;
}

/*
 * .cs request; don't check legality of optional arguments
 */
void casecs(void)
{
	int i, j;

	if (TROFF) {
		int savtr = trace;

		trace = 0;
		noscale++;
		skip();
		if (!(i = getrq()) || (i = findft(i)) < 0)
			goto rtn;
		skip();
		cstab[i] = atoi0();
		skip();
		j = atoi0();
		if(nonumb)
			ccstab[i] = 0;
		else
			ccstab[i] = findps(j);
	rtn:
		zapwcache(0);
		noscale = 0;
		trace = savtr;
	}
}


void casebd(void)
{
	int i, j, k;

	if (!TROFF) {
		n_casebd();
		return;
	}
	zapwcache(0);
	k = 0;
bd0:
	if (skip() || !(i = getrq()) || (j = findft(i)) == -1) {
		if (k)
			goto bd1;
		else 
			return;
	}
	if (j == smnt) {
		k = smnt;
		goto bd0;
	}
	if (k) {
		sbold = j;
		j = k;
	}
bd1:
	skip();
	noscale++;
	bdtab[j] = atoi0();
	noscale = 0;
}


void casevs(void)
{
	int i;

	if (!TROFF) {
		n_casevs();
		return;
	}
	skip();
	vflag++;
	dfact = INCH; /* default scaling is points! */
	dfactd = 72;
	res = VERT;
	i = inumb(&lss);
	if (nonumb)
		i = lss1;
	if (i < VERT) 
		i = VERT;
	lss1 = lss;
	lss = i;
}


void casess(void)
{
	int i;

	if(TROFF) {
		noscale++;
		skip();
		if(i = atoi0()) {
			spacesz = i & 0177;
			zapwcache(0);
			sps = width(' ' | chbits);
		}
		noscale = 0;
	}
}


Tchar t_xlss(void)
{
	/* stores \x'...' into two successive Tchars.
	/* the first contains HX, the second the value,
	/* encoded as a vertical motion.
	/* decoding is done in n2.c by pchar().
	*/
	int i;

	getch();
	dfact = lss;
	i = quant(atoi0(), VERT);
	dfact = 1;
	getch();
	if (i >= 0)
		*pbp++ = MOT | VMOT | i;
	else
		*pbp++ = MOT | VMOT | NMOT | -i;
	return(HX);
}

Uchar *unpair(int i)
{
	static Uchar name[3];

	name[0] = i & SHORTMASK;
	name[1] = (i >> SHORT) & SHORTMASK;
	name[2] = 0;
	return name;
}