DNeliac Example 72
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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 00000Again, 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 133CategoryDecompilation