How to write in EPCS

Excellent.

I'm not familiar with the old ASMI functions, but I'd guess the functions take similar arguments. You could try this:

alt_epcs_flash_read(p_epcs_fd, epcs_address, buffer_address, bytes_to_read);

where:

p_epcs_fd was initialised by the epcs_open() function earlier

epcs_address is the address offset into your EPCS device that you want to start reading from

buffer_address is a pointer to a suitable RAM buffer

bytes_to_read is the number of bytes to read!

So you could do this:

alt_u8 buffer[16];

alt_epcs_flash_read(p_epcs_fd, 0, (void*)buffer, 16);

to read the first 16 bytes of data into an array.

You can probably work out how the erase_block and write_block functions work by looking in altera_avalon_epcs_flash_controller.c

Note that the erase function erases the entire block (64k) containing the offset you pass to it.

P.S. num_epcs_regs is just telling you there is one region (512k made up of 8*64k blocks).