Atari Lynx specific information for cc65 <author>Karri Kaksonen, <htmlurl url="mailto:karri@sipo.fi" name="karri@sipo.fi"> Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org"> <date>2004-10-14 <abstract> An overview over the Atari Lynx runtime system as it is implemented for the cc65 C compiler. </abstract>  <toc>  <sect>Overview This file contains an overview of the Atari Lynx runtime system as it comes with the cc65 C compiler. It describes the memory layout, Lynx specific header files, available drivers, and any pitfalls specific to that platform. Please note that Lynx specific functions are just mentioned here, they are described in detail in the separate <htmlurl 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 The standard binary output format generated by the linker for the Lynx target is a machine language program with an executable header. It is of course possible to change this behaviour by using a modified startup file and linker config. You can also produce real carts with directory structures and encrypted headers by modifying the startup and linker config files. There is a simple example archive called <tt/lynx-cart-demo/ in the <htmlurl url="ftp://ftp.musoftware.de/pub/uz/cc65/contrib/" name="contrib directory"> that shows how to create a complete bootable Lynx cart. <sect>Memory layout cc65 generated programs with the default setup run with the I/O area and the kernal enabled, which gives a usable memory range of $400 - $BE3F. All boot ROM entry points may be called directly without additional code. Special locations: <descrip> <tag/Text screen/ No conio support is currently available for the Lynx. <tag/Keyboard/ The Lynx "flabode" keys, Opt 1, Pause and Opt 2 are implemented using the conio interface. The only characters the keyboard is able to produce are 'R' for Restart (Opt 1 + Pause), 'F' for flip (Opt 2 + Pause), 'P' for pause, '1' for Opt 1, '2' for Opt 2, '3' for Opt 1 + Opt 2 and '?' for all keys down at the same time. <tag/Stack/ The C runtime stack is located at $BE3F and growing downwards. <tag/Heap/ The C heap is located at the end of the program and grows towards the C runtime stack. </descrip> <sect>Platform specific header files Programs containing Lynx specific code may use the <tt/lynx.h/ header file. <sect1>Lynx specific functions <itemize> <item>lynx_change_framerate <item>lynx_eeprom_erase <item>lynx_eeprom_read <item>lynx_eeprom_write </itemize> <sect1>Hardware access The following pseudo variables declared in the <tt/lynx.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/MIKEY/</tag> The <tt/MIKEY/ structure allows access to MIKEY chip. See the <tt/_mikey.h/ header file located in the include directory for the declaration of the structure. <tag><tt/SUZY/</tag> The <tt/SUZY/ structure allows access to SUZY chip. See the <tt/_suzy.h/ header file located in the include directory for the declaration of the structure. </descrip> <sect>Loadable drivers <sect1>Graphics drivers A TGI driver for the standard graphics mode (160×102 in 16 colors) is available, but must be statically linked, because no file I/O is available. See the documentation for the <htmlurl url="co65.html" name="co65 utility"> for information on how to do that. The TGI driver is implemented as a dual buffering device. To use it as a single-buffer device set draw page and view page to the same value 0 or 1; The TGI driver has a few Lynx-specific extensions. Calling tgi_ioctl(0, spr) will display a standard Lynx sprite on screen. Calling tgi_ioctl(1, 0) will do a flip screen. If you decide to flip the screen then it may be a good idea to call the install-routine for the joystick to get that flipped too. Calling tgi_ioctl(2, bgindex) will set the text background color to the index defined by bgindex. If bgindex is 0 then the background color is transparent. <sect1>Extended memory drivers No extended memory drivers are currently available for the Lynx. <sect1>Joystick drivers A joystick driver for the standard buttons is available, but must be statically linked, because no file I/O is available. See the documentation for the <htmlurl url="co65.html" name="co65 utility"> for information on how to do that. The joystick will check to see if the screen is flipped or not in the install routine and adapt itself to the currect state. <sect1>Mouse drivers No mouse drivers are currently available for the Lynx. <sect1>RS232 device drivers No serial drivers are currently available for the Lynx. <sect>Limitations <sect>Other hints At this point in time there is no support for the cart filesystem yet. I have a <tt/lynx-cart-demo/ example project that uses an interrupt driven display, has support for the cart filesystem and an abcmusic sound module. At some point in time we may find a way to rewrite these to fit the way the cc65 drivers require. But for the time being you can create less portable applications using these Lynx specific modules in <tt/lynx-cart-demo/. <sect>Bugs/Feedback If you have problems using the library, if you find any bugs, or if you're doing something interesting with it, I would be glad to hear from you. Feel free to contact me by email (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">). <sect>License 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>