general square root for fasmg

sqrt.g

; with the remainder calculations can be split into pieces and extended later

calminstruction ROOT? result*, remainder*, N*
	local rem, prox, bit, temp
	compute rem, 0
	check N = 0
	jyes done

	compute prox, 0
	compute bit, 1 shl (((bsr N) + 1) and -2)

	check N > 0
	jyes more
	arrange bit, =err 'square root of negative number'
	assemble bit
	exit
more:
	compute temp, rem + bit + prox
	check N < temp
	compute rem, rem shr 1
	jyes reduce
	compute rem, rem + bit
	compute prox, temp
reduce:
	compute bit, bit shr 2
	check bit
	jyes more
done:
	publish result, rem
	compute rem, N - prox
	publish remainder, rem
end calminstruction

N = result * result + remainder. In this version the remainder is always >= 0.