__malloc()
{
	__heap=${1}

	if eval "\${${__heap}_size:+true}"; then
		# Empty heap
		__mr="${__heap}0"
		eval "${__heap}_size=1"
	elif eval "\${${__heap}_free_head:+false}"; then
		# No free blocks, grow heap
		eval "__mr=\${__heap}\${${__heap}_size}"
		eval "${__heap}_size=\$((\${${__heap}_size} + 1))"
	else
		# Free block(s) available, allocate
		eval "__mr=\${${__heap}_free_head}"
		if eval "\${${__mr}_next_free:+false}"; then
			# Last free block, clear heap's free list
			eval "${__heap}_free_head="
			eval "${__heap}_free_tail="
		else
			# Multiple free blocks, move heap's free list head
			eval "${__heap}_free_head=\${${__mr}_next_free}"
		fi
	fi
}

__free()
{
	__heap=${1}
	__ptr=${2}

	if eval "\${${__heap}_free_tail:+false}"; then
		# Empty free list
		eval "${__heap}_free_head=\${__ptr}"
		eval "${__heap}_free_tail=\${__ptr}"
	else
		# Non-empty free list, push to tail
		eval "__free_tail=\${${__heap}_free_tail}"
		eval "${__free_tail}_next_free=\${__ptr}"
		eval "${__heap}_free_tail=\${__ptr}"
	fi
	# Ensure next_free is null to delimit list end
	eval "${__ptr}_next_free="
}