these kinds of questions used to be best asked on dev ml, as developes might not have been monitoring this site, unfortunatelly im not sure they will be answered today even there.

Well, hardlinking with -lstdc solved the issue with compiling the library (The 'missing' Math operations are apparently here now in abiv1, as reading through 'too much' documentation revealed before I found what I needed).

Seems however the generated library is causing issues during runtime when trying to load functions from it. Currently programming in C, and I am using the original mpega-libmad headers compiling the software (seemed like the correct thing to do, although I do see there are some header files in contrib that seems to be derived from the original mpega.library (not libmad) package from aminet. I did also try these but they gave me an issue during compilation saying "mpegaBase is undefined". I assume this is due to changes in the madlib library structure compared to the original mpega.library. Haven't had time to investigate that further), the moment I run the MPEGA_open function in libmad, regardless if the function actually recieves a 'filename' to play, I get the following error, and Trap signal 11 :

Program failed
Task: 0xE9455370 - arrayplay
Error: 0X800000002 - Hardware bus fault/address error
PC : 0XE946F298
Module mpega.library Segment 1 .text (0xE9464E20) Offset 0X0000A478
Function __mallic_StdCBase_wrapper (0xE946F290) Offset 0x00000008
Wait for disk activity to finish.

Going more in-depth on the error I see that this issue is related to dos.library function CallEntry:

Stack trace:

0xE8CB4309 test1013 Function arrayplay + 0x000000AD
0xE7B5627A dos.library Function CallEntry + 0X0000004A
0xE7B53057 dos.library Segment 1 .text + 0X00002337
0XE7ADA090 kernel Segment 1 .text 0x00006090

I'm assuming this may be an issue caused by changes in abiv1, however the exact cause of the crash doesn't seem to be apparent. Maybe someone has some input on what might have changed here?

when it compiled, then it looks includes are in place and you just need a proper library to link with.
that may be tricky eventually, especially if this is c++ code. you might simply grep the target platform/developer/lib folder for what link libs contain the missing functions, as well as consult the mmakefiles of similar software, most likely in contrib subfolder of the source, to see, what they are linking with.

Question. When trying to compile mpega_libmad for 64 bit AROS I've come over an issue considering the source code is of older make (source was made for the older i386 compiler back in 2008). Of course, I had to change slib_entries to take 3 parameters, instead of 2, but apparently functions exp() memcpy() memmove() memset() are now undefined in the source. I do however still see most of these functions in the documentation. Is there an include required now for these functions that was not required before, or am I missing something?

There are undefined symbols in 'mpega.library':
U exp wrap_mpega.c:0
U memcpy layer3.c:0
U memmove wrap_mpega.c:0
U memset