_This page represents examples 72, 73, and 74 of Halstead's "Machine-Independent Computer Programming"._
_Comments in italics, as well as the disassembly and Algol hand translation, have been added by_
MikeVanEmmerik.
EXAMPLE 72.
Address ff jkb yyyyy Ad.dress ff jkb yyyyy
00522 00 000 00000 00565 12 130 00130
00523 65 000 00352 00566 10 030 00132
00524 65 000 00211 00567 14 031 00000
00525 16 030 00130 00570 61 000 00526
00526 16 030 00131 00571 65 000 00346
00527 16 030 00132 00572 12 500 00007
00530 12 300 00000 00573 10 030 00130
00531 10 030 00130 00574 27 515 00133
00532 27 500 00051 00575 61 000 00541
00533 61 000 00571 00576 72 500 00573
00534 10 030 00130 00577 11 530 00130
00535 27 500 00045 00600 61 000 00571
00536 61 000 00571 00601 10 030 00130
00537 65 000 00346 0060? 27 500 00004
00540 61 000 00526 00603 61 000 00571
00541 10 003 00000 00604 10 030 00130
00542 27 700 00005 00605 27 500 00057
00543 61 000 00553 00606 61 000 00571
00544 10 030 00131 00607 10 030 00130
00545 05 000 00003 00610 27 500 00047
00546 14 030 00467 00611 61 000 00571
00547 10 005 00000 00612 10 030 00130
00550 26 030 00467 00613 27 500 00077
00551 14 030 00131 00614 61 000 00571
00552 61 000 00561 00615 10 030 00130
00553 10 030 00132 00616 27 400 00042
00554 05 000 00003 00617 61 000 00526
00555 14 030 00467 00620 65 000 00346
00556 10 005 00000 00621 10 030 00130
00557 26 030 00467 00622 27 400 00042
00560 14 030 00132 00623 61 000 00526
00561 12 303 00001 00624 65 000 00265
00562 10 003 00000 00625 65 000 00363
00563 27 400 00017 00626 61 010 00522
00564 61 000 00571 00627 00 000 00000
_Again, here is MikeVanEmmerik's hand disassembly of the above:_
00522 START: .word 0
00523 call SUB_A
00524 call SUB_B
00525 st b,AA
00526 ENT_A: st b,AB
00527 st b,AC
00530 ld b,#0 ; Why is j=3?
00531 ld q,AA
00532 sub <>,q,#00051 ; Subtract and skip if result not equal to 0
00533 jmp ENT_B
00534 ld q,AA
00535 sub <>,q,#00045
00536 jmp ENT_B
00537 call SUB_C
00540 jmp ENT_A
00541 ENT_D: ld q,#0 ; Why is b=3?
00542 sub <,q,#5 ; subtract and skip if result < 0
00543 jmp ENT_F
00544 ld q,AB
00545 shl q,3
00546 st q,AD
00547 ld q,0(b)
00550 add q,AD
00551 st q,AB
00552 jmp ENT_E
00553 ENT_F: ld q,AC
00554 shl q,#3
00555 st q,AD
00556 ld q,0(b)
00557 add q,AD
00560 st q,AC
00561 ENT_E: add b,#1
00562 ld q,#0
00563 sub <,q,#00017 ; subtract and skip if result < 0?
00564 jmp ENT_B
00565 ld =,b,AB ; why is j=1?
00566 ld q,AC
00567 st q,0(b)
00570 jmp ENT_A
00571 ENT_B: call SUB_C
00572 ld b,#7 ; why is j=5?
00573 ld q,AA
00574 sub <>,q,AE(b) ; ?
00575 jmp ENT_D
00576 jmp ?
00577 ld <>,a,AA ; load a and skip if non zero
00600 jmp ENT_B
00601 ld q,AA
00602 sub <>,q,#4 ; subtract immediate 4 and skip if non zero
00603 jmp ENT_B
00604 ld q,AA
00605 sub <>,q,#00057
00606 jmp ENT_B
00607 ld q,AA
00610 sub <>,q,#00047
00611 jmp ENT_B
00612 ld q,AA
00613 sub <>,q,#00077
00614 jmp ENT_B
00615 ld q,AA
00616 sub =,q,#00042
00617 jmp ENT_A
00620 call SUB_C
00621 ld q,AA
00622 sub =,q,#00042
00623 jmp ENT_A
00624 call SUB_D
00625 call SUB_E
00626 jmp *START
00627 .word 0
_Here is MikeVanEmmerik's hand translation to Algol:_
integer procedure START();
begin
SUB A();
SUB B();
aa := 0;
ENT A:
ab := 0;
ac := 0;
k := 0;
if aa-058 <> 0 ;
else goto ENT B;
if aa-045 <> 0 ;
else goto ENT B;
SUB C();
goto ENT A;
ENT D:
if k-5 < 0 ;
else goto ENT F;
ad := ab * 2**3;
ab := m + ad;
goto ENT E;
ENT F:
ad := ac * 2**3;
ac := m + ad;
ENT E:
k := k+1;
if k - 017 = 0 ;
else goto ENT B;
i := ab;
[i] := ac;
goto ENT A;
ENT B:
SUB C();
m := 7;
for m := m step 1 until 0 do
begin
if aa - ae[m](0..14) <> 0 ;
else goto ENT D;
end;
if aa <> 0 ;
else goto ENT_B;
if aa-4 <> 0 ;
else goto ENT_B;
if aa-057 <> 0 ;
else goto ENT_B;
if aa-047 <> 0 ;
else goto ENT_B;
if aa-077 <> 0 ;
else goto ENT_B;
if aa-042 = 0 ;
else goto ENT_A;
SUB C();
if aa-042 = 0 ;
else goto ENT_A;
SUB D();
SUB E();
end
EXAMPLE 74.
SUB A 0 352
SUB B 0 211
SUB C 0 346
ENT A 0 526
ENT B 0 571
SUB D 0 265
SUB E 0 363
ENT C 0 522
ENT D 0 541
ENT E 0 561
ENT F 0 553
START 0 522
AA 3 130
AB 3 131
AC 3 132
AD 3 467
AE 3 133
CategoryDecompilation