Print table of 500 primes

gistfile1.asm

% Algorithm P: Print table of 500 primes
L	IS	500		% The number of primes to find
t	IS	$255		% Temporary storage
n	GREG	0		% Prime candidate
q	GREG	0		% Quotient
r	GREG	0		% Remainder
jj	GREG	0		% Index for PRIME[j]
kk	GREG	0		% Index for PRIME[k]
pk	GREG	0		% Value of PRIME[k]
mm	IS	kk		% Index for output lines
	LOC	Data_Segment
PRIME1	WYDE	2		% PRIME[1] = 2
	LOC	PRIME1+2*L
ptop	GREG	@		% Address of PRIME[501]
j0	GREG	PRIME1+2-@	% Initial value of jj
BUF	OCTA	0		% Place to form decimal string

	LOC	#100
Main	SET	n,3		% P1. Start table. n <- 3
	SET	jj,j0		% j <- 1
2H	STWU	n,ptop,jj	% P2. n is prime. PRIME[j+1] <- n
	INCL	jj,2		% j <- j + 1
3H	BZ	jj,2F		% P3. 500 found?
4H	INCL	n,2		% P4. Advance n
5H	SET	kk,j0		% P5. k <- 2 / k = ptop - kk 
6H	LDWU	pk,ptop,kk	% P6. n / PRIME[k] ?
	DIV	q,n,pk		%	q <- floor(n / PRIME[k])
	GET	r,rR		%	r <- n mod PRIME[k]
	BZ	r,4B		% To P4 if r = 0 for checking the next n
7H	CMP	t,q,pk		% P7. PRIME[k] large?
	BNP	t,2B		% To P4 if q <= PRIME[k]
8H	INCL	kk,2		% P8. Advance k. k <- k + 1
	JMP	6B		% To P6.
	GREG	@		% Base address
Title	BYTE	"First Five Hundred Primes"
NewLn	BYTE	#a,0
Blanks	BYTE	"   ",0		% String of three blanks
2H	LDA	t,Title		% P9. Print Title
	TRAP	0,Fputs,StdOut
	NEG	mm,2
3H	ADD	mm,mm,j0	% P10. Print line
	LDA	t,Blanks	% Output "   ".
	TRAP	0,Fputs,StdOut
2H	LDWU	pk,ptop,mm	% pk <- prime to be printed
0H	GREG	#2030303030000000	% " 0000",0,0,0
	STOU	0B,BUF		% Prepare buffer for decimal conversion
	LDA	t,BUF+4		% t <- position of units digit
1H	DIV	pk,pk,10	% pk <- floor(pk/10)
	GET	r,rR		% r <- next digit
	INCL	r,'0'		% r <- ASCII digit r
	STBU	r,t,0		% Store r in the buffer
	SUB	t,t,1		% Move one byte to the left
	PBNZ	pk,1B		% Repeat on remaining digits
	LDA	t,BUF		% Output " " and four digits
	TRAP	0,Fputs,StdOut
	INCL	mm,2*L/10	% Advance by 50 wydes
	PBN	mm,2B
	LDA	t,NewLn		% Output a newline
	TRAP	0,Fputs,StdOut
	CMP	t,mm,2*(L/10-1)	% P11. 500 printed?
	PBNZ	t,3B		% To P10 if not done
	TRAP	0,Halt,0