Echo #03 31 марта 1997

Программирование

Assembler - An interesting trick with the assembler.

           Tips and Tricks


(C) VfNG / NEW


   Do you want to fall? Those who do not know that
focus, what I am going to describe
just drop. Buy mats (no sports), lots of wool, iodine, and the 
nurse younger (useful).



   Tamp or upload the files of the following:

;----------------------------------------
        ORG # 6200
;----------------------------------------
        CALL # C000; initialization

                      ; Music

                      ; Module
;----------------------------------------
        DI; initialize

        LD HL, # 6000; IM 2

        LD B, L; Vector # 6000

        LD A, H; Procedure

        LD I, A; processing
        INC A; # C006, ie,
L1 LD (HL), A; player

        INC HL; ringtones

        DJNZ L1

        LD (HL), A

        LD L, H

        LD (HL), # C3

        INC HL

        LD DE, # C006; address of the procedure

        LD (HL), E; play

        INC HL

        LD (HL), D

        IM 2
;----------------------------------------
        LD HL, BEGIN; with

        LD BC, # C000-BEGIN-3; address
L2 LD (HL), # FB; BEGIN create

        INC HL; how intermeddle

        DEC BC; teams EI

        LD A, B

        OR C

        JR NZ, L2

        LD (HL), # C3; after all the piles

        INC HL; EI switch to

        LD DE, BEGIN; BEGIN

        LD (HL), E

        INC HL

        LD (HL), D
;---------------------------------------- BEGIN; EI: EI: EI .. 
. JP BEGIN ;----------------------------------------

        ORG # C000
;----------------------------------------
        INSERT "MUSIC"; some

                        ; Music

                ; Module in the compiled

                ; # C000. For example, from PT2

                , Or Sound Tracker'a.


   Let us estimate the logic of applets. At first she 
sinitsializiruet IM 2, then create a memory procedure, 
consisting of Continuum EI-NIS, and one purely for the JP

loop. Then this same procedure
start. Since it consists only of
EI, then for some team will interrupt, then the player would be 
called music from the speaker will pour sweet melody. All 
right? Run ... 


                   *


   You have already been discharged from hospital? As head? 
Still ache a little after the fall? Sorry that it happened. But 
I hope You still wonder why this program

worked some did not like from her
expected?


   A casket is opened simply. The thing is
Team EI. In fact, she not only
permit termination, but also ... prohibits them! At the time of 
the next a team. This focus is built into the Z80

to the end of processing procedures INT'a,
ending EI: RET, this is the RET
time to execute before the arrival of a new interrupt. Someone 
asks: what if EI: HALT, although this theory, they should call 
hang? Everything and then simply: in fact the team is not just 
waiting for HALT INT, and also knits socks varit cereal, change 
diapers and child generates as NOP. Here is the first of 
HALT'ovskih NOP'ov interrupt actually prohibited

and all the other does not.


   The question remains: where can this Thing
apply? Myself do not know yet ...