#!/bin/bash
# hawklink   -- linker for the Hawk, using the smal assembler
#   hawklink [parameters] a b c d e ...
#   hawklink -help   -- gives more documentation

# Author: Douglas W. Jones, Department of Computer Science, U. of Iowa.
# Copyright 2019, all rights released under Creative Commons CC0 license;
#	-- that is to say, the author wishes to retain no rights to this work.
# Warrantee:  It seems to work, what more can you ask of free software;
#	-- this code has been successfully used by hundreds of students,
#	-- and it would be nice if it worked for you as well.

# version 9/15/2019 -- use exit codes so it works in make scripts

myname=`basename $0`

if [ $# -lt 1 ]
then
	echo "$myname requires parameters"
	echo "$myname -help is available"
	exit 1
fi
if [ -help = $1 ]
then
	echo "$myname [options] a b c d e ...
	 links SMAL object and library files named a, b, c, d and e
	 into a new loadable file called link.o (by default)
	 no options are required, but the following are allowed:"
	echo "
	 -r nnnn   -- start relocatable code at nnnn (a hex address)
	 -c nnnn   -- start commons at nnnn (a hex address)
	 -m        -- suppress linking with standard monitor
	 -o ffff   -- direct output to file ffff.o instead of link.o
	 -d        -- dump the linker symbol table to link.d or ffff.d
	"
	exit 1
fi

# defaults for linkage

origin=1000			# default for -r option
common=10000			# default for -c option
monitor=monitor.o		# -m option undoes this
library=~dwjones/lib/hawk	# no option overrides this 
outfile=link			# default for -o option
dump=""				# default for -d option (don't dump)
smal="~dwjones/bin/smal32 -L -U ${library}"

# parse options -- loop exits on first non-option

while [ $# -gt 0 ]
do
	case $1 in
		-c)
			if [ $# -gt 1 ]
			then
				common=$2
				shift
				shift
			else
				echo "$myname -c nnn requires a hex number nnn"
				echo "$myname -help explains options"
				exit 1
			fi
			;;
		-r)
			if [ $# -gt 1 ]
			then
				origin=$2
				shift
				shift
			else
				echo "$myname -r nnn requires a hex number nnn"
				echo "$myname -help explains options"
				exit 1
			fi
			;;
		-m)
			monitor=""
			shift
			;;
		-o)
			if [ $# -gt 1 ]
			then
				outfile=$2
				shift
				shift
			else
				echo "$myname -o fff requires a file name fff"
				echo "$myname -help explains options"
				exit 1
			fi
			;;
		-d)
			dump="-D"
			shift
			;;
		-*)
			echo "$myname $1 option unknown"
			echo "$myname -help explains options"
			exit 1
			;;
		*)
			break
			;;
	esac
done

if [ $# -lt 1 ]
then
	echo "$myname found no object files"
	echo "$myname -help explains options"
	exit 1
fi

# build linker control file header

echo TITLE "$myname $*" > ${outfile}.a
echo ".=#${origin}" >> ${outfile}.a
echo "C=#${common}" >> ${outfile}.a
if [ -n "${monitor}" ]
then
	echo "USE \"${monitor}\"" >> ${outfile}.a
fi

# build linker control file body

while [ $# -gt 0 ]
do
	case $1 in
		-*)
			rm ${outfile}.a
			echo "$myname $1 unexpected option"
			echo "$myname -help explains command format"
			exit 1
			;;
		*)
			if [ -r $1 -o -r ${library}/$1 ]
			then
				echo "USE \"$1\"" >> ${outfile}.a
				shift
			else
				echo "$myname $1 unreadable object file"
				echo "$myname -help is available"
				exit 1
			fi
			;;
	esac
done

# build linker control file trailer

echo RUNUSED=C >> ${outfile}.a
echo RUNAVAIL=#20000 >> ${outfile}.a

# actually do the linkage

eval ${smal} ${dump} ${outfile}.a
exitcode=$?
rm ${outfile}.a

# cleanup

if [ -n "${dump}" ]
then
	sort -k2 -o ${outfile}.d ${outfile}.d
fi
exit ${exitcode}