Is it possible to "mix" a complete ASM code to a "C" high-level routine? I mean, to make ASM the "bigger" aplication?

You can have C calling asm, asm calling C .... IF you have a main() in C.

I have a project which is mainly C, but in one case the C call an asm routine that call a C function.

Just do remember that C functions may/will screw up ANY and ALL registers.

The easy way is to code it all in C (the routines to be assembler as 'skeletons') compile and link till no errors. Then use the SRC statement for the "C to become asm" routines, reextend them to .a51 and put the meat on the skeletons.

Erik