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ZX Review #3-4
22 июля 1997 |
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Forum - Dmitry Fyodorov: Print images with a mask with pixel precision. Algorithm for calculating the address coordinates to within a pixel.
(C) Denis Fedorov,
Vladivostok.
Bring to your attention
individual, in my opinion, programs. The idea to write something
sort of came after
in one of the rooms of your remarkable journal was published by
way of printing images with pixel accuracy without the use of
analogues protseduy PLOT. That same idea is present in my
version, but a little changed. Procedures for calculating the
display address and HLDOWN - also derived from published your
material.
If a memory place pristine copy of the screen, based on the
submitted program I can try to write how to restore the
original image.
Title: Printing pictures
with the mask up to a pixel.
Printing Method - RR, AND, OR.
FORMAT OF THE TEMPLATE - 1 mask, 2-byte
Figure 3-mask, a 4-figure ...
The second line - 1.2; 3,4; ....
Third, .... - ..............
Total LY lines with a length byte LX
each.
CALCULATION OF THE LENGTH OF PATTERN - LX *
LY * 2.
PRINTING MADE DIRECTLY ONTO THE SCREEN.
WARNING! If, for example, LY = 16,
LX = 2, then the template will have a size 2 * 2 familiarity.
This is because the unit izmereniniya LX - one byte, and LY -
one line.
To print was made in
buffer should be added after the ABC
lines:
LD DE, STEP
ADD HL, DE
where STEP - module differences
between the beginning of the real screen and
beginning of the buffer to be used for printing.
Check for collision with the boundaries of the screen is not
implemented. 148.
Special for INFORCOM by SatSoft.
(F.D.)
text: ORG 40000 - ANY OTHER
; PERMITTED
; VALUE
LD A, (LX); PREPARATION
LD (LENX +1), A; VARIABLES
LD A, (LY); FOR WORK
LD (LENY +1), A
LD IX, (START)
LD DE, (COORDS)
LD A, D; DETERMINATION
; Positions
AND 7 IN BYTE
LD (SHIFT +1), A
LD A, # BF; CALCULATION SCREEN
SUB E; ADDRESSES WITH PRECISION
LD C, A; UP LINES
AND # 38
RLCA
RLCA
SRL D
SRL D
SRL D
ADD A, D
LD L, A
LD A, C
RRCA
RRCA
RRCA
AND # 18
XOR C
AND # F8
XOR C
ADD A, # 40
ABC LD H, A
LEN-Y LD B, 0; CYCLE COLUMN
L3 PUSH BC
PUSH HL
LEN-X LD B, 0; LOOP LINES
L2 PUSH BC
LD C, (IX +0); Accepts the current
INC IX; DATA PATTERN
LD E, (IX +0)
INC IX
LD B, (IX +0)
INC IX
LD D, (IX +0)
INC IX
SHIFT LD A, 0; The shift
OR A; ON LINE
JR Z, CONT
L1 AND A
RR C
RR B
RR E
RR D
DEC A
JR NZ, L1
CONT LD A, (HL)
AND C
OR E
LD (HL), A
INC HL
LD A, (HL)
AND B
OR D
LD (HL), A
INC HL
POP BC
DJNZ L2
POP BC
POP HL
HLDOWN INC H; STAND HL
LD A, H; ON LINE DOWN.
AND 7
JR NZ, EDOWN
LD A, L
ADD A, 32
LD L, A
JR C, EDOWN
LD A, H
SUB 8
LD H, A
EDOWN DJNZ L3
RET
LY DEFB 0
LX DEFB 0
START DEFW 0000
COORDS DEFB 0; Y-COORD
DEFB 0; X-COORD
END
2
My version does not include things such as finding
the desired pattern according to its number in
table or binding source
Basic data for three reasons:
1.All is quite easy to
exercise, looking at the article
Mr. V. Bodrov - SCHEDULE YOUR
COMPUTER "(ZX REVIEW 95 / 4, p.
15).
2.Samostoyatelno worked with
procedure, changing it in various ways, the reader will better
understand structure of the algorithm and be able to
example, to implement checking
conflict with the boundaries of a template screen.
3. I try to do as much as possible
a simple program and modify it as needed.
Here it is worth examining
way to encode the initial
images in the format used by my procedure. Let's say
We have a ready-made image
fold in size 8, and
mask and the raster itself are in
different parts of the screen. In this
If we have to use the following methods:
148.
ORG 41000; ANY OTHER
; VALUE
MCOORD DEFW 0000
PCOORD DEFW 0000
YLEN DEFB 00
XLEN DEFB 00
MAIN LD A, (YLEN); length setting
LD (YL +1), A; PRINTS
LD A, (XLEN)
LD (XL +1), A
LD HL, (MCOORD); INSTALLATION
LD (CRD +1), HL; PARAMETERS
LD HL, START; FOR ENTRY
LD (ADR +1), HL; MASKS
CALL INPUT
LD HL, (PCOORD); INSTALLATION
LD (CRD +1), HL; PARAMETERS
LD HL, START +1; FOR ENTRY
LD (ADR +1), HL; RASTER
CALL INPUT
RET
CRD LD DE, 0000 CALCULATION OF DISPLAY
LD A, E; Nogo ADDRESSES
AND # 18; By coordinates
ADD A, # 40
LD H, A
LD A, E
AND 7
RRCA
RRCA
RRCA
ADD A, D
LD L, A
ADR LD DE, 0000 INSTALLATION ADDRESS
; Result
; UNIT
YL LD B, 00; COUNT Y-LENGTH
YLOOP PUSH BC
PUSH HL
XL LD B, 0; COUNTER X-LONG
XLOOP LD A, (HL)
LD (DE), A
INC DE
INC DE
INC HL
DJNZ XLOOP
POP BC
POP HL
DOWN INC H; DOWN HL
LD A, H; per pixel DOWN
AND 7
JR NZ, EDOWN
LD A, L
ADD A, 32
LD L, A
JR C, EDOWN
LD A, H
SUB 8
LD H, A
EDOWN DJNZ YLOOP
RET
END
2
In this case, START - start
the resulting block, PCOORD -
coordinates of the raster, MCOORD - then
same, except for the mask. Magnitude
M-and P-COORD, XLEN - are set in
familiarity and YLEN - in pixels.
In the process of creativity as
says new ideas are born.
So I have had such
idea. I have tried to develop
own algorithm for calculating the addresses of the coordinates
with an accuracy to the pixel. That's what I got:
148.
LD C,% 11100000
LD A, D
AND 7
LD B, A; offset within
SRL D; LINE
SRL D
SRL D
RR E
RR L
RR E
RR L
RR E
RR L
LD A, L
AND C
OR D
LD L, A; L - FORMED
LD A, E
AND C
CTRL OR% 01000000
LD H, A; H - FORMED
END
2
For their own purposes the algorithm uses registers A, BC,
HL, DE. Terms standatnye:
At the entrance - in DE koodinaty
At the exit - HL - corresponding
address.
Working with three senior bats
in the row labeled CTRL, you can
get the address printed on the other
memory page for ZX-SPECTRUM
print buffer.
And here's another idea.
If you ever have to write something like:
148.
XOR A
LD (VAR), A
LD B, 255
CALL .......
...............
LOOP LD A, (VAR)
INC A
LD (VAR), A
DJNZ LOOP
That such a device can be replaced
at:
LD B, 255
LOOP LD A, B
XOR # FF
LD (VAR), A
CALL .......
...............
DJNZ LOOP
2
Where VAR - variable designed to CALL ...... .
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