Schrijver
| filling VRAM with a color
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Pat
msx user
Berichten: 44 |  Geplaatst: 29 September 2005, 09:07 |
100hexadecimal = 256decimal = 100000000 binary = width of 9 bits ! > 8 bit -> doesn't fit in a byte !
use dw instead.
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ro
msx guru
Berichten: 2346 | Geplaatst: 29 September 2005, 10:09 |
I told ya screenwidth=256, didn't I.
The VDP commands CAN be done in DB (define byte) no biggy. Just remember that X,Y,XL,YL are 16 (actually 9) bit values!
so defining XL would be (#0100)
DB #00,#10
it's that! simple. just fill them 15 bytes correct and you'll be enjoying some nice screenfillings  |
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norakomi
msx professional
Berichten: 861 | Geplaatst: 29 September 2005, 10:52 |
AHA !!!
they are 9 bit values !!!!!
So if I would say:
Sxl: db 0
Sxh: db 1
thats the same as:
Sxl: db 256
Sxh: db 0
allright !!!
learned another thing today.
(I was allways wondering what the SxH (source x High bit)was for !!!
what about this:
sxl: db 40
sxh: db 1
syl: db 6
syh: db 0
is this the same as:
sxl: db 40
sxh: db 0
syl: db 7
syh: db 0
??
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ro
msx guru
Berichten: 2346 | Geplaatst: 29 September 2005, 12:04 |
Quote:
| AHA !!!
they are 9 bit values !!!!!
So if I would say:
Sxl: db 0
Sxh: db 1
thats the same as:
Sxl: db 256
Sxh: db 0
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euh, not really. a Byte CANNOT be 256 remember. max 255
so it would, atleast, be:
Sxl: db 0
Sxh: db 1
thats the same as:
Sxl: db 255
Sxh: db 0
If (since it's BYTE pixeling) 255 is rounded UP (and it would be logical, not?) then, YEAH it's the same. |
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ro
msx guru
Berichten: 2346 | Geplaatst: 29 September 2005, 12:05 |
Quote:
| sxl: db 40
sxh: db 1
syl: db 6
syh: db 0
is this the same as:
sxl: db 40
sxh: db 0
syl: db 7
syh: db 0
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nope. Only X is byte pixeling (when highspeed commanding the VDP) |
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GhostwriterP
msx addict
Berichten: 313 | Geplaatst: 29 September 2005, 12:11 |
Quote:
| If (since it's BYTE pixeling) 255 is rounded UP (and it would be logical, not?) then, YEAH it's the same.
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It will not be rounded up, you do need to put in 256 in NX wich means setting 9 bit (16bit).
During a HMMV the lowest bit wil be ignored so 255 will become 254.
so:
db 0
db 1
is the same as
dw 256
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ro
msx guru
Berichten: 2346 | Geplaatst: 29 September 2005, 12:17 |
I was wondering about that indeed, thanx for clearing that up Ghost
so:
Sxl: db 0
Sxh: db 1
thats NOT the same as:
Sxl: db 255
Sxh: db 0
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norakomi
msx professional
Berichten: 861 | Geplaatst: 29 September 2005, 18:32 |
Quote:
| Quote:
| If (since it's BYTE pixeling) 255 is rounded UP (and it would be logical, not?) then, YEAH it's the same.
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It will not be rounded up, you do need to put in 256 in NX wich means setting 9 bit (16bit).
During a HMMV the lowest bit wil be ignored so 255 will become 254.
so:
db 0
db 1
is the same as
dw 256
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thanx !!!!!!!!
and with that my problem is solved. |
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