So far the base address of the Ethernet chip was a general property of all Ethernet drivers. It served two purposes:
1. Allowing to use a single Ethernet driver for a certain Ethernet chip, no matter what machine was connected to the chip.
2. Allowing use an Ethernet card in all Apple II slots.
However, we now use customized Ethernet drivers for the individual machines so 1.) isn't relevant anymore. In fact one wants to omit the overhead of a runtime-adjustable base address where it isn't needed.
So only the Apple II slots are left. But this should rather be a driver-internal approach then. We should just hand the driver the slot number the user wants to use and have the driver do its thing.
Independently from the aspect if the driver parameter is a base address or a slot number the parameter handling was changed too. For asm programs there was so far a specific init function to be called prior to the main init function if it was desired to chnage the parameter default. This was done to keep the main init function backward compatible. But now that the parameter (now the slot number) is only used on the Apple II anyhow it seems reasonable to drop the specific init function again and just provide the parameter to the main init function. All C64-only user code can stay as-is. Only Apple II user code needs to by adjusted. Please note that this change only affects asm programs, C programs always used a single init function with the Apple II slot number as parameter.
parse_url stores the URL selector in the output_buffer - which is currently 520 bytes. A new entry point called parse_url_buffer was added which instead stores the URL selector in a buffer provided by the user.
url_download now calls the new parse_url_buffer instead of parse_url. The buffer for the URL selector is simply the download_buffer. So the download_buffer is used twice: First to hold the URL selector to be sent as request to the server and then to hold the response received from the server.
However, the URL selector still can't exceed the MSS (aka 1460 bytes).
Note: The User-Agent string was shortened by two bytes as that allows a "default" URL (incl. 'http://' but without port number) of exactly 1400 bytes to end up as 1460 bytes URL selector.
Note: The URL selector is stored in the output_buffer - which is currently 520 bytes. Beside all of the URL (apart from a potential "http://") the 'get' and the 'http_preamble' have to fit into that buffer. Therefore URLs mustn't exceed 450 chars. However, we omit a check to avoid further code size increase as most of the time URLs are known to be much shorter anyhow. If the URLs might become large we just leave it up to the user to check their length.
Together with the recent change to provide the inbound data buffer address and length to the TCP callback function as C parameters this change allows the TCP API to get along without any global variable :-)
In contrast to the multiple UDP callbacks there's only one TCP callback so it easy to provide a wrapper for the C callback that pushes C parameters on the stack.
The IP5 usage of ld65 segments and zeropage variables was made compatible with cc65 C programs already a while ago. This commit is the next logical step which is to introduce the actual C interface to IP65.
IP65 for C programs shares the the ip65.lib / ip65_tcp.lib with IP65 for assembler programs. However the various libraries from the 'drivers' are not reused. Instead there's exactly one library for every target named ip65_<target>.lib. Those libraries contain only functions used by ip65.lib / ip65_tcp.lib.
TODOs:
- Introduce c64_timer.s and atr_timer.s.
- Add a C interface to the rest of the IP65 functionality (especially TCP).
