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@soharu
Created Mar 24, 2014
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Print table of 500 primes
% 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
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