1 files changed, 116 insertions, 0 deletions
diff --git a/src/cmd/eqn/shift.c b/src/cmd/eqn/shift.c
new file mode 100644
index 00000000..dbac530b
--- /dev/null
+++ b/src/cmd/eqn/shift.c
@@ -0,0 +1,116 @@
+#include "e.h"
+#include "y.tab.h"
+
+void subsup(int p1, int p2, int p3)
+{
+	if (p2 != 0 && p3 != 0)
+		shift2(p1, p2, p3);
+	else if (p2 != 0)
+		bshiftb(p1, SUB, p2);
+	else if (p3 != 0)
+		bshiftb(p1, SUP, p3);
+}
+
+extern double Subbase, Supshift;
+extern char *Sub1space, *Sup1space, *Sub2space;
+extern char *SS1space, *SS2space;
+
+void bshiftb(int p1, int dir, int p2)
+{
+	int subps, n;
+	double shval, d1, h1, b1, h2, b2;
+	char *sh1, *sh2;
+
+	yyval = p1;
+	h1 = eht[p1];
+	b1 = ebase[p1];
+	h2 = eht[p2];
+	b2 = ebase[p2];
+	subps = ps;
+	ps += deltaps;
+	if (dir == SUB) {
+		/* base .2m below bottom of main box */
+		shval = b1 + EM(Subbase, ps);
+		ebase[yyval] = shval + b2;
+		eht[yyval] = max(h1-b1+shval+b2, h2);
+		if (rfont[p1] == ITAL && lfont[p2] == ROM)
+			n = 2;		/* Sub1space */
+		else
+			n = max(2, class[rclass[p1]][lclass[p2]]);
+		sh1 = pad(n);
+		rclass[p1] = OTHER;	/* OTHER leaves too much after sup */
+	} else {	/* superscript */
+		/* 4/10 up main box */
+		d1 = EM(Subbase, subps);
+		ebase[yyval] = b1;
+		shval = -(Supshift * (h1-b1)) - b2;
+		if (Supshift*(h1-b1) + h2 < h1-b1)	/* raise little super */
+			shval = -(h1-b1) + h2-b2 - d1;
+		eht[yyval] = h1 + max(0, h2 - (1-Supshift)*(h1-b1));
+		if (rclass[p1] == ILETF)
+			n = 4;
+		else if (rfont[p1] == ITAL)
+			n = 2;		/* Sup1space */
+		else
+			n = max(1, class[rclass[p1]][lclass[p2]]);
+		sh1 = pad(n);
+		rclass[p1] = rclass[p2];	/* OTHER leaves too much after sup */
+	}
+	dprintf(".\tS%d <- %d shift %g %d; b=%g, h=%g, ps=%d, subps=%d\n", 
+		yyval, p1, shval, p2, ebase[yyval], eht[yyval], ps, subps);
+	sh2 = Sub2space;	/* was Sub2space; */
+	printf(".as %d \\v'%gm'%s%s\\*(%d%s%s\\v'%gm'\n", 
+		yyval, REL(shval,ps), DPS(ps,subps), sh1, p2,
+		DPS(subps,ps), sh2, REL(-shval,ps));
+	rfont[p1] = 0;
+	sfree(p2);
+}
+
+void shift2(int p1, int p2, int p3)
+{
+	int subps;
+	double h1, h2, h3, b1, b2, b3, subsh, d2, supsh;
+	int treg;
+	char *sh2;
+
+	treg = salloc();
+	yyval = p1;
+	subps = ps;	/* sub and sup at this size */
+	ps += deltaps;	/* outer size */
+	h1 = eht[p1]; b1 = ebase[p1];
+	h2 = eht[p2]; b2 = ebase[p2];
+	h3 = eht[p3]; b3 = ebase[p3];
+	subsh = EM(Subbase, ps);
+	if (b1 > b2 + subsh) /* move little sub down */
+		subsh += b1;
+	eht[yyval] = max(subsh+b2-b1+h1, h2);
+	supsh = -Supshift*(h1-b1) - b3;
+	d2 = EM(Subbase, subps);
+	if (h3 < (1-Supshift)*(h1-b1))
+		supsh = -(h1-b1) + (h3-b3) - d2;
+	ebase[yyval] = subsh + b2 - b1;
+	eht[yyval] = h1 + subsh+b2-b1 + max(0, h3-(1-Supshift)*(h1-b1));
+	dprintf(".\tS%d <- %d sub %d sup %d, ps=%d, subps=%d, h=%g, b=%g\n",
+		yyval, p1, p2, p3, ps, subps, eht[yyval], ebase[yyval]);
+	if (rclass[p1] == ILETF)
+		sh2 = "\\|\\|";
+	else
+		sh2 = SS2space;
+	/*n = max(class[rclass[p1]][lclass[p2]], class[rclass[p1]][lclass[p3]]);
+	/*sh2 = pad(max(2, n));
+	*/
+	printf(".ds %d %s\\*(%d\n", p2, SS1space, p2);
+	nrwid(p2, subps, p2);
+	printf(".ds %d %s\\*(%d\n", p3, sh2, p3);
+	nrwid(p3, subps, p3);
+	printf(".nr %d \\n(%d\n", treg, p3);
+	printf(".if \\n(%d>\\n(%d .nr %d \\n(%d\n", p2, treg, treg, p2);
+	printf(".as %d %s\\v'%gm'\\*(%d\\v'%gm'\\h'-\\n(%du'\\\n", 
+		p1, DPS(ps,subps), REL(subsh,subps), p2, REL(-subsh,subps), p2);
+	printf("\\v'%gm'\\*(%d\\v'%gm'\\h'-\\n(%du+\\n(%du'%s%s\n", 
+		REL(supsh,subps), p3, REL(-supsh,subps), p3, treg, DPS(subps,ps), Sub2space);
+	if (rfont[p2] == ITAL)
+		rfont[yyval] = 0;	/* lie */
+	rclass[yyval] = rclass[p3];	/* was OTHER */
+	sfree(p2); sfree(p3); sfree(treg);
+}