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.
