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EnigmA Amiga Run 1995 November
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EnigmA AMIGA RUN 02 (1995)(G.R. Edizioni)(IT)[!][issue 1995-11][Skylink CD].iso
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AmigaAGA-EVD.doc
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1995-10-13
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FEATURES:
- 8-bit refresh code rewritten. Now it's up to 1.8 times faster
(especially in doublescan modes) than my refresh routine in
ShapeShifter 3.1 (and over 25 times faster than in ShapeShifter 3.0)
- Added support for 15-bit mode with fast conversion to HAM8.
- Old 2- and 4-bit routines are added (for your comfort :) )
- All refresh routines convert only screen changes ("delta" buffer)
- Now all refresh routines are safer and don't trash screen when bitmap
width isn't multiple of 64 (ShapeShifter allows multiple of 16)
Note: HAM8 render routine is very fast but gives very low quality so I
optimized it for some standard MacOS GUI colors. Especially small
objects like icons, non-standard gadgets are not very readable.
Refreshing with "delta" buffer isn't as fast as in other modes
because always full lines must be converted to HAM. So 15-bit
mode is good only for truecolor graphics previews, picture
viewers, etc. not for real work.
REQUIREMENTS:
AGA chipset (for 8-bit screen and HAM8)
OS3.0+ (interleaved bitmaps)
ShapeShifter 3.2 or later (ShapeShifter 3.1 had a bug in RTYPE_CUSTOM
refresh)
A lot of FastMem :) AmigaAGA-EVD uses the same amount of memory as
ShapeShifter 3.1 but remember to leave space for screen buffers in
memory configuration window.
How to calculate it:
For 640x480x8 screen driver needs 640*480*2=614400 bytes (2 - because
one buffer is used by ShapeShifter for screen buffer and second by
driver for "delta" buffer)
For 640x480x15 screen driver uses 1228800 bytes.
Writing 24-bit driver is possible and it isn't a problem but it
requires very much memory because all pixels are stored as 32bit
words. For 640x480x24 screen over 2.4MB would be used and this mode
would be even slower than 15-bit but quality will not be better at all.
HOW TO USE:
Set "Screen type" as "External" and select name of driver in "External
driver" string gadget. Set screen mode, width and height. Width should
be multiple of 64, i.e. 448, 512, 576, 640, 704, 768, 832, etc.
Suggested refresh rates for 030/25MHz systems:
2-bit mode: 2 or even 1
4-bit mode: 3-5
8-bit mode: 4-6
15-bit mode: 5-10
Above values are good for Multiscan 640x480.
For QuickTime animations use small screen and higher rate, f.e.:
- for 512x300x4 (only greys) set refresh to 2 or 3 - you get smoother
animation than even in 1bit mode
- for 448x300x8 (color mode) set refresh to 3
AUTHOR:
AmigaAGA-EVD was written in Devpac assembler on Amiga 4000/030 using
"ShapeShifter External Video Driver Interface Specification (Level 1)"
by Christian Bauer. Chunky2plannar routines were based on several
sources from Aminet and Deli's DrWho Genie.
All comments/bug reports send to:
Pawel Hernik
Nowowiejska 24/3
25-532 Kielce
POLAND
tel/fax (041)27012
E-mail: spi-ph@srv1.tu.kielce.pl (letters)
phernik@sabat.tu.kielce.pl (uuencodes)
THANX TO:
- Christian Bauer for making great emulator and External Video Driver
specifications
- Peter Kunath for DrWho Genie source code and his c2p routine
- also to James McCoull and Peter McGavin for making chunky2plannar
conversion on Amiga really fast
DISTRIBUTION:
AmigaAGA-EVD is FREEWARE. You may use and copy this driver freely but
all files must be copied in an unmodified state preferably in LhA or
LZX archive. Use it at your own risk. If you use AmigaAGA-EVD and
you like it send me a postcard or message via e-mail.
HISTORY:
1.0 (20.9.95) - never released because of bug in ShapeShifter 3.1,
15-bit support added and 8-bit c2p routines changed
1.1 (1.10.95) - first release, c2p routine changed again (thanx to
Peter Kunath), now it is slower a bit (about 4%) but
hasn't such restrictions like previous routine and is
simplier a lot.