Buzz #10 16 сентября 1997

Ассемблер     Программирование

Assmbler - A beautiful effect "Burning sprite.

                     ASSEMBLER *** ***


(C) Paracels' DYK.


   The appearance of this column is due to its extraordinary 
popularity in all the computer magazines. We decided not to 
deprive you - our Readers of this joy, but to say that does not 
claim the status of steep encoders, etc. 

   We decided not to teach you assembly language, because now 
he knows everyone (or almost everyone) but simply give 
assm'ovskie texts nekrtoryh effects and explanations for them.


   We hope that this column will get everything related to the 
assembler: effects of useful utilities that xor'ki etc. What 
specifically will print under the heading 'ASSEMBLER' depends, 
first of all, from us and, of course, from you. 

   Possibly leading this category, we do learn something steep 
and share with you, but for now give the text a simple but 
beautiful effect 'BURNING Sprite'. Posneniya front lines to 
help you better understand the effect of the work. 

   The effect is based on processing the sprite logical 
operations AND, OR and XOR, thanks to which is obtained by the 
fire. Size sprite you can set the variables X_SIZE and Y_SIZE. 
Metka SHIT indicates the beginning of your sprite (where it is 
stored as a list of DEFB bytes, you can load it INCBIN'om). 

   Another thing: when you create a sprite leave the top
margin of 2-3 familiarity to last-minute "embers" flew higher, 
that will look very nice. 

   And here's the text ...

X_SIZE EQU 4; size of the sprite X (in the familiarity).
Y_SIZE EQU 32; size of the sprite Y (in pixels).


        ORG 25000
LOOP EI

        HALT

        DI

        CALL GOREN; Call Subroutine burning sprite.

        LD A, # 7F

        IN A, (# FE); Poll .

        RRA

        JR C, LOOP

        EI

        RET

GOREN LD HL, SHIT; Address sprite.

        EXX

        LD C, 0

        LD DE, 16384; Address screen to print a sprite.

        LD L, E

        LD H, D
X_COOR PUSH DE

        LD B, X_SIZE
X_COOR2 EXX

        LD A, R; Take the "random" number in A fills

        LD E, A; in E. Endymion And the number 7 and records in 
D. 

        AND 7

        LD D, A

        EX DE, HL; HL = address of the screen, DE = address of 
the sprite. 

        XOR (HL); Ksor and the contents of the screen increases
        INC L; ourselves to address in the HL and do contain OR
        OR (HL); zhimym HL.


        EX DE, HL; HL = address of the sprite, DE = address of 
the screen. 


        EXX; replaces registers: HL = DE = address of the screen

                           , (In this case # 4000/16384).


        EX DE, HL; HL = # 4000, DE = # 4000.

        AND (HL); Endymion and the contents of the screen.

        EX DE, HL; HL = # 4000, DE = # 4000.


        EXX; replaces registers: HL = address of the sprite,

                           ; DE = address of the screen.


        OR (HL); Endymion A byte sprite

        INC HL; increase the address in HL.

        EXX; replaces registers: HL = # 4000, DE = # 4000

        LD (HL), A; Writes a (HL) (HL = # 4000) contents

                           ; Register A, ie fills the screen.


        INC E; Increase L and E: DE = # 4001,

        INC L; HL = # 4001


        DJNZ X_COOR2; Reduce B; if not zero, then the transition
                           ; Go on X_COOR2


        POP DE; Restore DE. DE = # 4000.

        LD L, E; L = E = # 00

        LD H, D; H = D = # 40


        CALL INC_DE; proceed to obtain routine

                           ; Lower addresses screen.


        INC C; Increment C,

        LD A, C; record in A and compared with height

        CP Y_SIZE; your sprite Y.

        JR NZ, X_COOR; If not zero, ie C is not equal to Y, then

                           ; Go to X_COOR.


        EXX; replaces registers.

        RET

; Sub-get low address display in DE.
INC_DE INC D

        LD A, D

        AND 7

        RET NZ

        LD A, E

        ADD A, 32

        LD E, A

        RET C

        LD A, D

        SUB 8

        LD D, A

        RET

SHIT DEFB 0,0,0,0,0,0,0,0

        DEFB 0,0,0,0,0,0,0,0

        DEFB 0,0,0,0,0,0,0,0

        DEFB 0,0,0,0,0,0,0,0

        DEFB 0,0,0,0,0,0,0,0

        DEFB 0,0,0,0,0,0,0,0

        DEFB 0,0,0,0,0,0,0,0

        DEFB 0,0,0,0,0,0,0,0

        DEFB 102,253,153,240,102,193,155,0

        DEFB 102,193,155,0,102,193,155,0

        DEFB 102,193,155,0,102,193,155,0

        DEFB 102,193,155,0,60,241,251,112

        DEFB 102,193,155,48,102,193,155,48

        DEFB 102,193,155,48,102,193,155,48

        DEFB 102,193,155,48,102,193,155,48

        DEFB 102,193,153,240,0,0,0,0


   Well, good luck!


                                                 Paracels' DYK.