.ds Bf b		\" default format; use i for icons and faces
.ds Bn /tmp/btroff\n($$	\" temporary file, reused on each macro call
.ds Bp /usr/lib/btroff	\" bitmap filter
.de BM
.if \\n(.$=1 .ds Bf \\$1
.if \\n(.$=2 \{.	\" copy request, perhaps diverted
.ie '\\n(.z'' .Bm \\$1 \\$2
.el \!.BM \\$1 \\$2\}
.if \\n(.$=4 \{.	\" size request, numerator only
.nr Bz \\$2
.sy \\*(Bp -s -\\*(Bf -d\\n(Bz \\$1 | awk '{\
	print ".nr \\$3 " $1; \
	print ".nr \\$4 " $2; \
	exit }' >\\*(Bn
.so \\*(Bn
.sy /bin/rm -f \\*(Bn \}
.if \\n(.$=5 \{.	\" size request, numerator and denominator
.nr Bz \\$2
.sy \\*(Bp -s -\\*(Bf -d\\n(Bz \\$1 | awk '{\
	print ".nr \\$4 " $1 "/\\$3"; \
	print ".nr \\$5 " $2 "/\\$3"; \
	exit }' >\\*(Bn
.so \\*(Bn
.sy /bin/rm -f \\*(Bn \}
..
.de Bm			\" copy request, for real
.if \\n(.P>0 \{.	\" maybe
.fl
.ie '\\$2'0' \{.	\" ask driver to read the bits
.br
\\X'Bitmap \\$1'
.sp -1 \}
.el \{.			\" use the Bitmap font
.sy \\*(Bp -\\*(Bf -d\\$2 \\$1 >\\*(Bn
.fp 9 BM Bitmap
.ft 9
.ps \\$2
.cf \\*(Bn	\" next line is for pm to consume
\!n0 1
.ft
.ps
.sy /bin/rm -f \\*(Bn \}
.fl \}
..