Comments on: Courtesy: Larry Wall, PERL MONGER FOUNDER DEVELOPER:KeyBoard Not found Press F1 to Continue: Programming logic, messages, and logic in software and in nepalese society http://www.everestuncensored.org/8404/2009/11/29/courtesy-larry-wall-perl-monger-founder-developerkeyboard-not-found-press-f1-to-continue-programming-logic-messages-and-logic-in-software-and-in-nepalese-society/ Express Yourself Tue, 07 Sep 2010 19:22:21 +0000 http://wordpress.org/?v=2.7 hourly 1 By: /* You are not expected to understand this */ http://www.everestuncensored.org/8404/2009/11/29/courtesy-larry-wall-perl-monger-founder-developerkeyboard-not-found-press-f1-to-continue-programming-logic-messages-and-logic-in-software-and-in-nepalese-society/#comment-15434 /* You are not expected to understand this */ Sun, 29 Nov 2009 04:26:11 +0000 http://www.everestuncensored.org/?p=8404#comment-15434 Comments I do feel guilty about Doing 32-bit multiplication and division on a 16-bit machine like the PDP-11 needs cleverness. My PDP-11 C compiler used subroutines to do long * and /. The multiplication routine was / / 32-bit multiplication routine for fixed pt hardware. / Implements * operator / Credit to an unknown author who slipped it under the door. .globl lmul .globl csv, cret lmul: jsr r5,csv mov 6(r5),r2 sxt r1 sub 4(r5),r1 mov 10.(r5),r0 sxt r3 sub 8.(r5),r3 mul r0,r1 mul r2,r3 add r1,r3 mul r2,r0 sub r3,r0 jmp cret which is neat, and I wasn't smart enough to figure it out. I don't feel guilty, though, because I didn't then know who suggested it and I did acknowledge the fact. Comments I do feel guilty about
Doing 32-bit multiplication and division on a 16-bit machine like the PDP-11 needs cleverness. My PDP-11 C compiler used subroutines to do long * and /. The multiplication routine was

/
/ 32-bit multiplication routine for fixed pt hardware.
/ Implements * operator
/ Credit to an unknown author who slipped it under the door.
.globl lmul
.globl csv, cret

lmul:
jsr r5,csv
mov 6(r5),r2
sxt r1
sub 4(r5),r1
mov 10.(r5),r0
sxt r3
sub 8.(r5),r3
mul r0,r1
mul r2,r3
add r1,r3
mul r2,r0
sub r3,r0
jmp cret

which is neat, and I wasn’t smart enough to figure it out. I don’t feel guilty, though, because I didn’t then know who suggested it and I did acknowledge the fact.

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