Inferno #03 22 ноября 2002

Программирование

Gamedev - WORM-255F. Python game code size of 255 bytes with the comments.

; WORM-255F tinygame
; By Shiru Otaku/ANGEL2 18.o9.2oo2
; Mailto: shiru@mail.ru

; This programm is a game
, "Python" in size 255 bytes.
; I am sure that more can be done in short,
, But at 128 bytes for all lotion
And she still does not fit:).

; This version uses some
; Sub 48basic rom (poll BREAK).
; This version uses a very simplistic
; RND - on the value of the register R.
; This version has sound effects through
; Hriper (integer 2).
; In this version, the squares, rabbits blink
; (Not FLASNem).
; In this version of the serpent's head is selected
; A different color.
; Game anyway that was on the screen before it
; Run (all the attributes
; Use the same INK and PAPER).

; Management - SINCLAIR JOY.
; Exit game - BREAK KEY (IY, and stack
; Not spoil).

And the maximum length of a serpent - 255.


WORMBUF EQU # C16F; buffer address serpent

                   , (So cunning because

                   , That the least significant byte

                   , Addresses and

                   , Used in

                   , Initialize the new

                   ; Game.

WORMCOL EQU # 2D; color of the snake, only

                   ; Odd (bit 0

                   ; Is set).
RAMKCOL EQU # 09; color edge of the field, only

                   ; Odd.


; Go ...

 ORG # C000

; Start a new game - management here
, And passed at startup, and
; Restart due gamovera.

START

; Clear the playing field and at the same time
; Draw within a field - it is more profitable than
; Separately clear the screen and draw
; Frame (takes less).
; Within a field, we need to make it easier
; Define touch snake edge of the field at
; Color. It will be shorter than the check
; Value of the address of the head of the serpent
; Attributes (almost doubled).

; In HL - beginning of attributes.

 LD HL, # 5800

; Painted over the top edge of the color line
; The playing field.

 LD B, # 20
 LD A, RAMKCOL
 LD (HL), A
 INC HL
 DJNZ $ -2

And now paint the 22 lines - the first byte
; As a land of 30 bytes to 0, the last byte
; Line too as the edge.

 LD B, 22
SUDA
 LD (HL), A
 INC HL

; And if the outer loop goes on DJNZ,
, Then the inner (30 bytes) - to register with,
, We decrement it until an
; Carry flag.

 LD C, # 1E
 LD (HL), 0
 INC HL
 DEC C
 JR NZ, $ -4
 LD (HL), A
 INC HL
 DJNZ SUDA

, And paint the bottom line, too, the color edge
; The playing field.

 LD B, # 20
 LD (HL), A
 INC HL
 DJNZ $ -2

; Initialize variables play. Set
The length of a serpent equal to 4 cm. Realistically it will be
3 familiarity, 4-well-because the latter
; Element of the serpent - a zero color displays,
, Eliminates the need for cleaning the screen
And each cycle.

 LD A, 4
 LD (WORMLEN), A

; Writes a variable color border deuce
, Red (type gamover)
; Saving bytes through the use of RRA.
; Variables are needed to color the border
; Changed with a delay, but not immediately, though.

 RRA
 LD (BORDCOL), A

; Initialize buffer serpent. Here
, Used the low byte address
; Buffer (stored in the HL) to
, And enter it into memory as the least significant byte
, Addresses the attributes and values ​​for the cycle
; Simultaneously.
; Cycle at the same time is longer than required
, (# 71 times), but this is not essential - but
, Saving two bytes per cycle without DJNZ.


         LD HL, WORMBUF
 ADD A, L

 LD (HL), A
 INC HL
 LD (HL), # 59
 INC HL
 DEC A
 JR NZ, $ -6

; Writes to the variable direction
; Serpent command code DEC HL (# 2B) This means
, That at the start of the game snake moves to the left.

 LD A, # 2B
 LD (WORMDIR), A

; Call subroutine output of the new
; Rabbit-rabbit. Sub-used
, Because "that generation of a new rabbit needs
; Twice - at the start and when eaten
; Old rabbit.

 CALL GENKROL


; Now begins the main game loop.

MAINLOOP

; As an address variable BORDCOL
, Used a direct reference to the byte
; Operand LD A, n - allows
; Save extra bytes of code
; At this point we have to actually register A
; Store is not 0, and the color of the curb.

BORDCOL = $ +1
 LD A, 0

; Colors border in that color.

 OUT (# FE), A

, And enters into a variable BORDCOL unit
- The next time a blue border
, (As would HALTy - eyes have time to see
; Previous color).

 LD A, 1
 LD (BORDCOL), A

And the variable KROLADR - address the current
; Rabbit in the field of attributes - as
; Keep the team (LD HL, nn).

KROLADR = $ +1
 LD HL, 0

And the variable color rabbit is also stored in
; Team. It is necessary to flash the rabbit
- We can not use FLASH
; Why we are not cleaned properly
; Screen area, and who knows what was on the
; Garbage (because we are not going to hope that all
; The right colors are set out
; BASIC-boot:)
; Initially, this variable is # 36
; (Green INK and PAPER)

KROLCOL = $ +1
 LD A, # 36
 LD (HL), A

; Draw a serpent. Its length is stored in
; Team LD B, n. It must be remembered that the length of
; Serpent actually 1 less than that stored in the
; This variable - after tail snake
; Draw one more familiarity with black.

WORMLEN = $ +1
 LD B, 0
 LD HL, WORMBUF

The color of the current familiarity serpent we store in
; Register A. Initially, it is zero,
, Because we will bring the snake from the end to
; Top (it will save several
; Bytes per zatiralke tail).

 XOR A

; Copy the stack buffer address in the snake
; IX - is shorter than the load it there
; As LD IX, nn (in bytes).

 PUSH HL
 POP IX

, Series O serpent.

PRWORM0

; Take the address of the buffer the serpent in the DE (the 
address in ; Of attributes, no origin - of

; Them long to count).

 LD E, (HL)
 INC HL
 LD D, (HL)
 INC HL

; Colors familiarity to that address color
; From the register A.

 LD (DE), A

; First familiarity (tail) colored
; Zero, and now we ship in the A color
; Proper carcass serpent (the loss of velocity on
; Extra commands in the loop are not fatal -
; Size is important to us:).

 LD A, WORMCOL

; Simultaneously with the conclusion we move the address
; Buffer serpent to its tail - if you do
; It separately with the conclusion of the program
, Becomes longer.
; Because in IX, we kept the same as in
; HL - use the relative displacement,
; Still, even at zero bias bytes
; It is spent.

 LD (IX-2), E
 LD (IX-1), D
 INC IX
 INC IX
 DJNZ PRWORM0

; After DE cycle was addressed head
; Serpent - if we want to highlight it
; A different color, then do it
, (But does not look very nice, so that
And you can not select, and save three
; Bytes). I have highlighted included brightness

 XOR 64
 LD (DE), A

, In case if the length of a serpent, we will increase
; Copy the last address of the head thereof in
; Next cell buffer (it indicates
; HL cycle after withdrawal).

 LD (HL), E
 INC HL
 LD (HL), D

; Swap HL and DE, as now we need to
; Find the new address of the head of
; Attributes, and it is more convenient to do
; Register HL.

 EX DE, HL

; In BC, we load the # 20 - adding to
; HL and BC could get a new address
, While moving down. The eldest of the couple
; (B) we do not load, because it after
; Last DJNZ zero.

 LD C, # 1920

; Logical to assume that the motion
; Up we need to subtract from HL BC.
; But we did not do that, because Team
; SUB HL, BC occupies two bytes of memory
And instead of a single byte command ADD HL, BC.
; The problem is not superfluous byte, but in that
; New address, we compute
; Self-modifying code, and
; Upward movement we had to-be
; Modify two bytes (for the remaining
; Place; NOP), while for other
; Areas need to modify all
; One. Therefore, we are spending on three bytes
; Boot in a couple of DE values ​​# FFE0.
; This value is a negative number
, # 20, and if we add it to the HL, then
, We actually do the same thing as
And if taken away would-# 20.

 LD DE, # FFE0

; WORMDIR variable points to an address in
; Memory, in which we are in the control unit
; Serpent write commands INC HL / DEC HL
; / ADD HL, BC / ADD HL, DE, depending on the
; Selected direction.

WORMDIR = $
 NOP

And now return back to the address found
; DE, as it is we still need to
; Determine whether the death of the snake on
; Different circumstances and for the record
; To the last cell buffer when the serpent
; Survive.

 EX DE, HL

; Breath for seven interrupt -
; It to play was real, but at the same time
, So that you can behold the flashing border
; At sedenii rabbits or death serpent.

 LD B, 7
 HALT
 DJNZ $ -1

;'s Change the color of the rabbit to a new (simulating
; FLASH) XOR `om. For this variable address
; Colored rabbit to take in HL, as us his
; Back to record again.
; Old color rabbit remains in register C
; For further checks

 LD HL, KROLCOL
 LD A, (HL)
 LD C, A
 XOR 9
 LD (HL), A

; Now delve into the stomach to snake
; Know, have not eaten, we someone (a
For example:). To begin with we learn, was not there-
; Eaten rabbit.

 LD A, (DE)

; So the rabbit or not?

 CP C
 JR NZ, CHKDEAD; Not that I know ...

; Similarly, rabbit!
; Well, then, would be to lengthen the serpent and
; Generate new rabbit.
; Extend. But there is one subtlety - the length of
; Serpent given us a single byte, and
; The case if a player - a giant of a large
; Joystick, you will need to provide
; The case when the length of a serpent was equal to 255.
; To not become it after a rabbit
; Serpent-invisible:) Because after INC (HL)
; Check the overflow flag, and if something
- Restore the status quo. That is,
And if the serpent was a length of 255, it is so and
; Left.

 LD HL, WORMLEN
 INC (HL)
 JR NZ, $ +3
 DEC (HL)

, Continues to lengthen the serpent - will increase
, A pointer to the head of the serpent in the IX for two
, (Ie one character). It should be noted
; That without these teams do not
, (As it might seem) - because then IX
, Would indicate a head snake, and the
; Previous cell buffer, and then the serpent -
; Khan.

 INC IX
 INC IX

, We will invite to the stage of a new rabbit:).

 CALL GENKROL

; After GENKROL in register A is always zero -
; It and puts us in a place where shavali
; Rabbit - so that when testing for death
; Serpent not to take the remains of a rabbit for
; Something else

 LD (DE), A

; To celebrate at the mercy of a hare
; Fun Wink green border.

 LD A, 4
 LD (BORDCOL), A

, And along with Pickney:) Since peak to another
; Reasons we will not - will not
; Make pikalku a subroutine. When
; Work pikalki important value of the register A7
- It needed to keep the color of the curb (to
, While there is a beeping, he has not changed). As
; Well what it's there now and there ..
; In case C we have the duration of Picanya
; (Outer loop).

 LD C, 70
; To make a sound - it is necessary to change the value
, The fourth bit in the port # FE from 0 to 1
 XOR 16
 OUT (# FE), A
; Make the delay between a change in values
; Bit, and length of the current value
; The outer loop, it was not just to
, Peak, and with the change of frequency.
 LD B, C
 DJNZ $
 DEC C
 JR NZ, $ -8

And now check, not whether we are dead-
; Chance (bite himself / edge of the screen).
; Check is most convenient using
; Team RRA (one byte), because the colors of the whole
; Tasteless - the walls, all sorts of snakes - we have
, Is given an odd number. Accordingly,
; Of these items after the RRA established
; Carry flag. If we ate the rabbit -
; Flag is not established, because in pikalke we
; Entered on the register A is an even number
, (Thrown down from least significant bit).

CHKDEAD

, Died? ..

 RRA
 JR NC, NODEAD; No !:)..

; Oops ... My zhuby ...
; On this occasion, to bring sound
; Breaking of teeth). It is similar to
; Previous pikalke, only the sound is
; Not a pure tone and noisy - we will
; Change the value of the fourth bit according
; From what we find in the register R. And do not
; Forget the junior three-bit register A
; To keep the number of 2 - red border.

 LD C, 250
 LD A, R

         AND 18
 OR 2
 OUT (# FE), A
 LD B, C
 DJNZ $
 DEC C
 JR NZ, $ -12

; ... And the sound of crumbling jaw
; Run the game again ...

 JP START

; And if we do not podohli up to this point -
, Then we need to write the new address of the head
; Snake at the end of the buffer. Only we must remember
, That after a cycle output pointer to the address
, (The one in the IX - HL we have long zaportili)
, 2 more than necessary (INC'i something
; Perform), and if we are on elongated
; Eaten rabbit - then the value of IX as
, Just what is necessary, but separate
; Zapisyvalki address will eat the extra bytes.
; In general, puts DE not to IX, and address
, Is 2 less than (specify a relative
; Displacement).

NODEAD
 LD (IX-1), D
 LD (IX-2), E

; Now we posproshat keyboard, rather than
; Poke-a player in her hard blunt
; Objects? .. Especially in the area of ​​key
, 67,890 (Sinclair joy)? ..

 LD BC, # EFFE

; In HL have addressed WORMDIR - byte to
; Be modified depending on the
; Poking a player (or leave unchanged,
; If the user is tired to engage in this nonsense).

 LD HL, WORMDIR
 IN A, (C)

; Check bits poluryada 67,890 will not
; By BIT n, r, and not with CP n -
, Both of these methods guzzle two bytes, and we
; Need to check all poluryad. Because
; Advantageous to use single-byte
; Command RRA (check would have to in order
; Repetition bit keys, and once bit
; To miss - the 0 key, it is our
; Not used).

 RRA
 RRA
 JR C, $ +4
; Button is pressed up (9) - fills in
; WORMDIR opcode ADD HL, DE
 LD (HL), # 19
 RRA
 JR C, $ +4
; Button is pressed down (8) - record in the
; WORMDIR opcode ADD HL, BC
 LD (HL), # 09
 RRA
 JR C, $ +4
, Pressed the right button (7) - fills in
; WORMDIR opcode INC HL
 LD (HL), # 23
 RRA
 JR C, $ +4
; Button is pressed to the left (6) - fills in
; WORMDIR opcode DEC HL
 LD (HL), # 2B

; At last check, has not pressed, whether the player
; BREAK (and there are such grief:).
; Check by a reputable
; Routines ROM BASIC48. If not pressed -
, Leaving the cycle, if you click ...
 CALL # 1F54
 JP C, MAINLOOP

; ... Well, if pressed, and Song for saying good ...
 RET


; It - subroutine address generation
; Rabbits, she enters discharge the KROLADR,
; She checks - no, if anything bad things
, Where the rabbit was going to appear, and so on.
; RND used very bad, just
; On the register R, but for this game is
; Justified (other ways to gobble up a lot
, B).
; Algorithm for generating addresses in the right
; Range is also very stupid (but plows).

GENKROL

; First Generate byte address - it
, Must be within # 58 .. # 5A.
; This can be achieved, to generate the number of
, 0 .. 2 (AND `th, and if you came out 3 - is
; Generate again). Then add to
; This number # 58, and receive byte
; Address.

 LD A, R
 LD H, 3
 AND H
 CP H
 JR Z, GENKROL
 ADD A, # 58
 LD H, A

; Now generate low byte address
, Its value may be within
, # 00 .. # FF, so that no additional
; Perversion is not required.
 LD A, R
 LD L, A

, Check that the attribute is in
; Generated address, and if it is a serpent
, Or the edge of the field - are generating the address again.

 LD A, (HL)
 CP 0
 JR NZ, GENKROL

; Writes the generated address in the
; Variable KROLADR.

 LD (KROLADR), HL

; As you can see, the output from this
; Subroutine register A is always zero
- This property routines used
; Above.

 RET

; That's all.