panic("No program space") on second call of pio_add_program

[berndbenner]

I am searching for a strange panic-error on loading the second pio program. ( pico-sdk version 1.5.1 ).

I have a panic("No program space").

What happens:

The first pio program to load has a length of 13. pio_find_offset_for_program(pio, program) returns 19 pio_add_program_at_offset will set: uint32_t program_mask = (1u << program->length) - 1; This is 0x1FFF (8191)

your bitvector array marker _used_instruction_space has only 32 bit per pio. _used_instruction_space[pio_get_index(pio)] |= program_mask << offset; will be set to 0xFFF80000.

The second program to load has a length of 10. so uint32_t program_mask = (1u << program->length) - 1; will be set to 0x3FF ( 1023)

and pio_find_offset_for_program

// work down from the top always
 for (int i = 32 - program->length; i >= 0; i--) {
    if (!(used_mask & (program_mask << (uint) i))) {
              return i;
   }
 }

will not find a free offset address.

It seems pio_find_offset_for_program with the "work down from the top" code is a little untested with more than one program loads! (4 x max 15 bit mask) will not fit in a 32 bit vector per pio.

Please change all allocation masks to 64 bit or use another partitioning algorythm.

I will send you my source code changes. I have changed all allocation masks to 64 bit and it works. pio_fixes.c.txt

[lurch]

your bitvector array marker _used_instruction_space has only 32 bit per pio.

That's because each PIO only has a 32-word instruction memory, so it uses 32-bits to keep track of which of the 32 instruction-slots have been used already.

Doing some back-of-the-envelope calculations, if your first 13-instruction program gets loaded at offset 19 (i.e. it's using instruction-slots 19 to 31 inclusive), shouldn't your second 10-instruction program get loaded at offset 9 (i.e. using instruction-slots 9 to 18 inclusive) ? ( 0xFFF80000 & (0x3FF << 9) equals zero )

(4 x max 15 bit mask) will not fit in a 32 bit vector per pio.

Huh?

[berndbenner]

Ok Thank you! I have missunderstand the docs. So 4 state machines has a maximum of 32 instructions in sum!