I need a little digital io for my project since cortex-m is not economical for me I need to know can i use Cortex-a to do some embedded jobs?
I think you can have a look at NXP i.MX6 series products
Another not very obvious difference in assembler conversion is the shift operations. On x86 shifts amounts are modulo the register size so <<32 does nothing. On ARM it would zero the register - but it is module 256 which is strange. On the ARM 64 bit architecture it does the same thing as x86. This can catch you out if you write a routine to extract bits from a variable bit position or to rotate a value for instance. The C standard says shifting by the size of the register or more is undefined, but when people write their code they sometimes assume their code is following the standard so this becomes a nasty gotcha.
https://david.wragg.org/blog/2012/11/shift-instructions.html
This is why you might sometime see code like ((w0 >> 1) >> ( 31-sh)) | (w1 << sh)
where sh must be within 0..31. For rotate there's an intrinsic or code on the web.
Yep it does sound like a lot of timers and I guess external clocks too. So it really depends on how much they each have to do and how quickly, but also you'll have storage requirements for all the routines and their data. Are you hoping to use the controller as a low level sequencer for most operations rather than get signals back as each job is done? That's a common sort of job for Cortex M microprocessors but a Cortex A series gives you extra speed and size.