(C) Ivan Roshchin, Moscow, 1998
This beautiful effect is the first time I saw on the PC,
the program Dos Navigator (Screen saver 'iris. Ss'), and
transferred it at the Spectrum. Here is the full text of the
program with detailed comments:
M_X EQU 7; Scale X
M_Y EQU 7; Scale Y
ORG # 6000
; Set attributes:
HALT
LD HL, # 5800
LD DE, # 5801
LD BC, # 2FF
LD (HL), L
LDIR
; Draw the grid:
LD HL, # 4000
LP1 LD A,% 01010101
BIT 0, H
JR NZ, NE_FF
CPL
NE_FF LD (HL), A
INC HL
LD A, H
CP # 58
JR NZ, LP1
; Main loop:
MAIN_LP LD IX, BUFER + # 2FF
; Buffer filled "from end to beginning"
, And in the same order will be displayed
; On the screen in the procedure TO_SCR.
LD H, TAB / # 100
LD DE, (M_3)
LD A, 24
LOOP_V EX AF, AF '
LD BC, (M_1)
EXX
LD B, 32
LOOP_H EXX
LD A, (MEM_BP)
LD L, C
ADD A, (HL)
LD L, B
ADD A, (HL)
LD L, E
ADD A, (HL)
LD L, D
ADD A, (HL)
AND # 7F
; Significant bit accumulator reset, and
; Buffer is populated with the # 00 - # 7F.
; This is useful in the procedure TO_SCR.
LD (IX), A
DEC IX
INC C;!
ADR_MX LD A, M_X
ADD A, B
LD B, A
EXX
DJNZ LOOP_H
EXX
ADR_MY LD A, M_Y
ADD A, E
LD E, A
INC D;!
EX AF, AF '
DEC A
JP NZ, LOOP_V
LD HL, (MEM_BP)
DEC HL;!!
LD (MEM_BP), HL
LD A, L
XOR H
LD HL, BUFER + # 2FF
XOR (HL)
XOR E
XOR C
ADD A, D
ADD A, B
LD B, A
LD HL, NAPR
AND 3
LD D, 0
LD E, A
ADD HL, DE
LD A, (HL)
BIT 3, B
JR NZ, TO_DEC
CP 3
JP P, TO_END
INC (HL)
JR TO_END
TO_DEC CP # FD
JP M, TO_END
DEC (HL)
TO_END LD A, (NAPR)
LD HL, M_1
ADD A, (HL)
LD (HL), A
LD A, (M_2)
LD HL, NAPR +1
SBC A, (HL)
LD (M_2), A
LD A, (NAPR +2)
LD HL, M_3
ADD A, (HL)
LD (HL), A
LD A, (M_4)
LD HL, NAPR +3
SBC A, (HL)
LD (M_4), A
CALL TO_SCR; Displays
XOR A; Something
IN A, (254); pressed?
CPL
AND 31
JR NZ, OBR_Z
; If not pressed, restoring
, The scale of the X and Y:
CALL INC_M
JP MAIN_LP
; Button is pressed Z (Zoom)?
OBR_Z LD A, # FE
IN A, (254)
BIT 1, A
RET NZ; If not - go
; If pressed - Scales:
CALL DEC_M
JP MAIN_LP
MEM_BP DW 0
M_1 DB 0
M_2 DB 0
M_3 DB 0
M_4 DB 0
NAPR DB 2,1,3,4
;----------------------------------; Procedures INC_M and DEC_M
increase , And reduce the scale:
INC_M LD HL, ADR_MX +1
LD A, (HL)
CP M_X
JR NC, INC_Y
INC (HL)
INC_Y LD HL, ADR_MY +1
LD A, (HL)
CP M_Y
RET NC
INC (HL)
RET
DEC_M LD HL, ADR_MX +1
LD A, (HL)
AND A
JR Z, DEC_Y
DEC (HL)
DEC_Y LD HL, ADR_MY +1
LD A, (HL)
AND A
RET Z
DEC (HL)
RET
;----------------------------------; Procedure TO_SCR recode
bytes ; From the buffer using a palette and
; The result as a file attribute:
TO_SCR LD HL, PALETTE; palette
LD DE, # 5800; screen
LD BC, BUFER + # 2FF; end of the buffer
HALT
LP_S LD A, (BC)
LD L, A
LDI
, Ie take a byte from the buffer and place
; In the register L. This will be offset in
; Panel (which is why it should start
; To address the multiple # 100). LDI team
; Take a byte from the palette (HL) and put
; On the screen at (DE), which
; Increased by 1. The situation in the buffer (BC)
, Decreases by 1. The fact that HL is also
; Increased by 1, no role
; Played since H does not change (because
, That in the buffer are the values 0 .. # 7F),
, And L is still unchanged at the next
; Step.
LD A, (BC)
LD L, A
LDI
LD A, (BC)
LD L, A
LDI
LD A, (BC)
LD L, A
LDI
LD A, (BC)
LD L, A
LDI
LD A, (BC)
LD L, A
LDI
LD A, (BC)
LD L, A
LDI
LD A, (BC)
LD L, A
LDI
LD A, D
CP # 5B
JP NZ, LP_S
RET
;--------------------------------; Auxiliary buffers and tables:
ORG # C000
; Auxiliary table begins
; To address the multiple # 100:
TAB
DB # 40, # 40, # 40, # 40, # 40, # 40, # 40, # 40
DB # 3F, # 3F, # 3F, # 3F, # 3F, # 3E, # 3E, # 3E
DB # 3E, # 3D, # 3D, # 3D, # 3C, # 3C, # 3B, # 3B
DB # 3B, # 3A, # 3A, # 39, # 39, # 38, # 38, # 37
DB # 37, # 36, # 35, # 35, # 34, # 34, # 33, # 32
DB # 32, # 31, # 30, # 30, # 2F, # 2E, # 2E, # 2D
DB # 2C, # 2C, # 2B, # 2A, # 29, # 29, # 28, # 27
DB # 26, # 25, # 25, # 24, # 23, # 22, # 22, # 21
DB # 20, # 1F, # 1E, # 1E, # 1D, # 1C, # 1B, # 1B
DB # 1A, # 19, # 18, # 17, # 17, # 16, # 15, # 14
DB # 14, # 13, # 12, # 12, # 11, # 10, # 10, # 0F
DB # 0E, # 0E, # 0D, # 0C, # 0C, # 0B, # 0B, # 0A
DB # 09, # 09, # 08, # 08, # 07, # 07, # 06, # 06
DB # 05, # 05, # 05, # 04, # 04, # 03, # 03, # 03
DB # 02, # 02, # 02, # 02, # 01, # 01, # 01, # 01
DB # 01, # 00, # 00, # 00, # 00, # 00, # 00, # 00
DB # 00, # 00, # 00, # 00, # 00, # 00, # 00, # 00
DB # 01, # 01, # 01, # 01, # 01, # 02, # 02, # 02
DB # 02, # 03, # 03, # 03, # 04, # 04, # 05, # 05
DB # 05, # 06, # 06, # 07, # 07, # 08, # 08, # 09
DB # 09, # 0A, # 0B, # 0B, # 0C, # 0C, # 0D, # 0E
DB # 0E, # 0F, # 10, # 10, # 11, # 12, # 12, # 13
DB # 14, # 14, # 15, # 16, # 17, # 17, # 18, # 19
DB # 1A, # 1B, # 1B, # 1C, # 1D, # 1E, # 1E, # 1F
DB # 20, # 21, # 22, # 22, # 23, # 24, # 25, # 25
DB # 26, # 27, # 28, # 29, # 29, # 2A, # 2B, # 2C
DB # 2C, # 2D, # 2E, # 2E, # 2F, # 30, # 30, # 31
DB # 32, # 32, # 33, # 34, # 34, # 35, # 35, # 36
DB # 37, # 37, # 38, # 38, # 39, # 39, # 3A, # 3A
DB # 3B, # 3B, # 3B, # 3C, # 3C, # 3D, # 3D, # 3D
DB # 3E, # 3E, # 3E, # 3E, # 3F, # 3F, # 3F, # 3F
DB # 3F, # 40, # 40, # 40, # 40, # 40, # 40, # 40
; Palette that determines the color effect
, Starts with the address of a multiple # 100:
PALETTE
DB # 09, # 09, # 09, # 09, # 09, # 09, # 09, # 09
DB # 09, # 09, # 09, # 0B, # 0B, # 0B, # 0B, # 0B
DB # 0B, # 0B, # 0B, # 0B, # 0B, # 0B, # 1B, # 1B
DB # 1B, # 1B, # 1B, # 1B, # 1B, # 1B, # 1B, # 1B
DB # 1A, # 1A, # 1A, # 1A, # 1A, # 1A, # 1A, # 1A
DB # 1A, # 1A, # 1A, # 12, # 12, # 12, # 12, # 12
DB # 12, # 12, # 12, # 12, # 12, # 12, # 16, # 16
DB # 16, # 16, # 16, # 16, # 16, # 16, # 16, # 16
DB # 36, # 36, # 36, # 36, # 36, # 36, # 36, # 36
DB # 36, # 36, # 36, # 34, # 34, # 34, # 34, # 34
DB # 34, # 34, # 34, # 34, # 34, # 34, # 24, # 24
DB # 24, # 24, # 24, # 24, # 24, # 24, # 24, # 24
DB # 25, # 25, # 25, # 25, # 25, # 25, # 25, # 25
DB # 25, # 25, # 25, # 2D, # 2D, # 2D, # 2D, # 2D
DB # 2D, # 2D, # 2D, # 2D, # 2D, # 2D, # 29, # 29
DB # 29, # 29, # 29, # 29, # 29, # 29, # 29, # 29
; Intermediate buffer may begin
; From any address:
BUFER DS # 300
How can I experiment with this
program:
- Change the scale (and constant M_X
M_Y). This can be done directly
during the program by pressing
'Z'.
- Instead of commands INC C and INC D, placed ennyh! "You
can put the commands that increase (or decrease) of registers C
and D is at 1, and to any other number.
- Command DEC HL, placed such training is essential "!!",
can replace some of these teams
(Or, for example, commands INC HL).
- Change the contents of the table TAB.
- Change the color set by
palette (array of PALETTE).
You can change all of the above
parameters directly during the program, if you make it
self-modifying.
*
