mirror of
https://github.com/cc65/cc65.git
synced 2024-12-27 00:29:31 +00:00
292 lines
8.8 KiB
Plaintext
292 lines
8.8 KiB
Plaintext
<!doctype linuxdoc system>
|
|
|
|
<article>
|
|
|
|
<title>Oric Atmos-specific information for cc65
|
|
<author>
|
|
<url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">,<newline>
|
|
<url url="mailto:polluks@sdf.lonestar.org" name="Stefan A. Haubenthal">,<newline>
|
|
<url url="mailto:greg.king5@verizon.net" name="Greg King">
|
|
<date>2015-01-09
|
|
|
|
<abstract>
|
|
An overview over the Atmos runtime system as it is implemented for the cc65 C
|
|
compiler.
|
|
</abstract>
|
|
|
|
<!-- Table of contents -->
|
|
<toc>
|
|
|
|
<!-- Begin the document -->
|
|
|
|
<sect>Overview<p>
|
|
|
|
This file contains an overview of the Atmos runtime system as it comes with the
|
|
cc65 C compiler. It describes the memory layout, Atmos-specific header files,
|
|
available drivers, and any pitfalls specific to that platform.
|
|
|
|
Please note that Atmos-specific functions are just mentioned here, they are
|
|
described in detail in the separate <url url="funcref.html" name="function
|
|
reference">. Even functions marked as "platform dependent" may be available on
|
|
more than one platform. Please see the function reference for more
|
|
information.
|
|
|
|
|
|
|
|
<sect>Binary format<p>
|
|
|
|
The standard binary output format generated by the linker for the Atmos target
|
|
is a machine language program with a one-line BASIC stub that jumps to the
|
|
machine-language part through <tt/CALL/. It has one sacrificial byte attached
|
|
to the end (a bug in the Oric ROM means that BASIC can put a variable on top
|
|
of the last byte that was loaded). It has a 24-byte tape header. A file can
|
|
be CLOADed as a BASIC program, and started by typing <tt/RUN/. The standard
|
|
load address is $501.
|
|
|
|
|
|
|
|
<sect>Memory layout<p>
|
|
|
|
In the standard setup, cc65-generated programs use the memory from
|
|
$0501 to $9800; so, nearly 37K of memory (including the stack) is
|
|
available. ROM calls are possible without further precautions.
|
|
|
|
If your program needs more memory, and it won't use TGI graphics, then you can
|
|
use the ld65 command-line option, <tt/-D __GRAB__=1/, when building the
|
|
program, to include the graphics screen RAM. Then, nearly 44K of memory
|
|
($0501 to $B400) is available.
|
|
|
|
Special locations:
|
|
|
|
<descrip>
|
|
<tag/Stack/
|
|
The C runtime stack is located at $97FF (or $B3FF), and grows
|
|
downwards.
|
|
|
|
<tag/Heap/
|
|
The C heap is located at the end of the program, and grows towards the C
|
|
runtime stack.
|
|
|
|
</descrip><p>
|
|
|
|
|
|
|
|
<sect>Platform-specific header files<p>
|
|
|
|
Programs containing Atmos-specific code may use the <tt/atmos.h/ header file.
|
|
|
|
|
|
<sect1>Atmos-specific functions<p>
|
|
|
|
The functions listed below are special for the Atmos. See the <url
|
|
url="funcref.html" name="function reference"> for declaration and usage.
|
|
|
|
<itemize>
|
|
<item>atmos_load
|
|
<item>atmos_save
|
|
<item>atmos_explode
|
|
<item>atmos_ping
|
|
<item>atmos_shoot
|
|
<item>atmos_tick
|
|
<item>atmos_tock
|
|
<item>atmos_zap
|
|
</itemize>
|
|
|
|
|
|
<sect1>Hardware access<p>
|
|
|
|
The following pseudo variables declared in the <tt/atmos.h/ header file do allow
|
|
access to hardware located in the address space. Some variables are
|
|
structures; accessing the struct fields will access the chip registers.
|
|
|
|
<descrip>
|
|
|
|
<tag><tt/VIA/</tag>
|
|
Access to the VIA (Versatile Interface Adapter) chip is available via the
|
|
<tt/VIA/ variable. The structure behind this variable is explained in <tt/_6522.h/.
|
|
|
|
</descrip><p>
|
|
|
|
|
|
|
|
<sect>Loadable drivers<p>
|
|
|
|
<em>Note:</em> Since the Atmos doesn't have working disk I/O
|
|
(see <ref id="limitations" name="section "Limitations"">), the
|
|
available drivers cannot be loaded at runtime (so the term "loadable drivers"
|
|
is somewhat misleading). Instead, the drivers have to be statically linked. While
|
|
this may seem overhead, it has two advantages:
|
|
|
|
<enum>
|
|
<item>The interface is identical to the one used for other platforms
|
|
and to the one for the Atmos once it has disk I/O.
|
|
<item>Once disk I/O is available, existing code can be changed to load drivers
|
|
at runtime with almost no effort.
|
|
</enum>
|
|
|
|
The names in the parentheses denote the symbols to be used for static linking of the drivers.
|
|
|
|
|
|
<sect1>Graphics drivers<p>
|
|
|
|
The default drivers, <tt/tgi_stddrv (tgi_static_stddrv)/,
|
|
point to <tt/atmos-240-200-2.tgi (atmos_240_200_2_tgi)/.
|
|
|
|
<descrip>
|
|
|
|
<tag><tt/atmos-228-200-3.tgi (atmos_228_200_3_tgi)/</tag>
|
|
This driver was written by Greg King and Stefan Haubenthal.
|
|
It features a resolution of 228×200 with a palette of two colors that
|
|
can be chosen from the Atmos's eight colors. The driver supports a third
|
|
palette-"color" that actually "flips" the pixel (it becomes the other color)
|
|
that is on the screen under the graphics cursor.
|
|
|
|
<tag><tt/atmos-240-200-2.tgi (atmos_240_200_2_tgi)/</tag>
|
|
This driver was written by Stefan Haubenthal and Greg King.
|
|
It features a resolution of 240×200 with black and white colors.
|
|
It is the default graphics driver for the Atmos.
|
|
|
|
</descrip><p>
|
|
|
|
|
|
<sect1>Extended memory drivers<p>
|
|
|
|
No extended memory drivers are currently available for the Atmos.
|
|
|
|
|
|
<sect1>Joystick drivers<p>
|
|
|
|
<descrip>
|
|
|
|
<tag><tt/atmos-pase.joy (atmos_pase_joy)/</tag>
|
|
Supports two standard joysticks connected to the P.A.S.E. interface of the Atmos.
|
|
|
|
</descrip><p>
|
|
|
|
|
|
<sect1>Mouse drivers<p>
|
|
|
|
No mouse drivers are currently available for the Atmos.
|
|
|
|
|
|
<sect1>RS232 device drivers<p>
|
|
|
|
<descrip>
|
|
|
|
<tag><tt/atmos-acia.ser (atmos_acia_ser)/</tag>
|
|
Driver for the Telestrat integrated serial controller and the Atmos with a
|
|
serial add-on.
|
|
Note that, because of the peculiarities of the 6551 chip, together with the
|
|
use of the NMI, transmits are not interrupt driven; and, the transceiver
|
|
blocks if the receiver asserts flow control because of a full buffer.
|
|
|
|
</descrip><p>
|
|
|
|
|
|
|
|
<sect>Limitations<label id="limitations"><p>
|
|
|
|
<sect1>Disk I/O<p>
|
|
|
|
The existing library for the Atmos doesn't implement C file I/O. There are
|
|
hacks for the <tt/read()/ and <tt/write()/ routines in place, which will make
|
|
functions work that read from <tt/stdin/ and write to <tt/stdout/ and
|
|
<tt/stderr/ (such as <tt/printf()/). However, those functions have some
|
|
shortcomings which won't be fixed, because they're going to be replaced
|
|
anyway.
|
|
|
|
To be more concrete, that limitation means that you cannot use any of the
|
|
following functions (and a few others):
|
|
|
|
<itemize>
|
|
<item>fclose
|
|
<item>fopen
|
|
<item>fread
|
|
<item>fprintf
|
|
<item>fputc
|
|
<item>fscanf
|
|
<item>fwrite
|
|
<item>...
|
|
</itemize>
|
|
|
|
|
|
|
|
<sect>Other hints<p>
|
|
|
|
|
|
<sect1>Function keys<p>
|
|
|
|
They are defined to be FUNCT + a number key.
|
|
|
|
|
|
<sect1>Capitals lock<p>
|
|
|
|
The keyboard's "CAPS Lock" mode is turned off while the program is running.
|
|
The previous mode (usually, CAPS Lock turned on [because Oric BASIC keywords
|
|
must be UPPER-case]) is restored when the program stops.
|
|
|
|
|
|
<sect1>Passing arguments to the program<p>
|
|
|
|
Command-line arguments can be passed to <tt/main()/. Since that is not
|
|
supported directly by BASIC, the following syntax was chosen:
|
|
|
|
<tscreen><verb>
|
|
RUN:REM arg1 " ARG2 IS QUOTED" ARG3 "" ARG5
|
|
</verb></tscreen>
|
|
|
|
<enum>
|
|
<item>You must turn <tt/CAPS/ lock off (tap CTRL-T) when you want to type
|
|
lower-case arguments (but, <tt/RUN/ and <tt/REM/ must be UPPER-case).
|
|
<item>Arguments are separated by spaces.
|
|
<item>Arguments may be quoted.
|
|
<item>Leading and trailing spaces around an argument are ignored. Spaces within
|
|
a quoted argument are allowed.
|
|
<item>The first argument passed to <tt/main()/ is the program name.
|
|
<item>A maximum number of 10 arguments (including the program name) are
|
|
supported.
|
|
</enum>
|
|
|
|
|
|
<sect1>Automatic starting<p>
|
|
|
|
Usually, a cc65-built program just will sit quietly in memory, after it is
|
|
CLOADed. It waits for you to start it (by typing BASIC's <tt/RUN/ command).
|
|
But, if you want to create a program that will start running immediately after
|
|
it is loaded, then you can use the linker command-line option
|
|
<tt/-D __AUTORUN__=$C7/.
|
|
|
|
|
|
<sect1>Interrupts<p>
|
|
|
|
The runtime for the Atmos uses routines marked as <tt/.INTERRUPTOR/ for
|
|
interrupt handlers. Such routines must be written as simple machine language
|
|
subroutines and will be called automatically by the interrupt handler code
|
|
when they are linked into a program. See the discussion of the <tt/.CONDES/
|
|
feature in the <url url="ca65.html" name="assembler manual">.
|
|
|
|
|
|
|
|
<sect>License<p>
|
|
|
|
This software is provided 'as-is', without any expressed or implied
|
|
warranty. In no event will the authors be held liable for any damages
|
|
arising from the use of this software.
|
|
|
|
Permission is granted to anyone to use this software for any purpose,
|
|
including commercial applications, and to alter it and redistribute it
|
|
freely, subject to the following restrictions:
|
|
|
|
<enum>
|
|
<item> The origin of this software must not be misrepresented; you must not
|
|
claim that you wrote the original software. If you use this software
|
|
in a product, an acknowledgment in the product documentation would be
|
|
appreciated but is not required.
|
|
<item> Altered source versions must be plainly marked as such, and must not
|
|
be misrepresented as being the original software.
|
|
<item> This notice may not be removed or altered from any source
|
|
distribution.
|
|
</enum>
|
|
|
|
</article>
|