Poly RaspberryPi PIO mode

poly-pio-mode.el

;; Simple Polymode for RaspberryPi Pico PIO files that uses 
;; both asm-mode as host-mode and c-mode for pass-through section

(define-hostmode poly-pio-hostmode
  :mode 'asm-mode)

(define-innermode poly-pio-c-innermode
  :mode 'c-mode
  :head-matcher "^% c-sdk {$"
  :tail-matcher "^%}$"
  :head-mode 'poly-head-tail-mode
  :tail-mode 'poly-head-tail-mode)

(define-polymode poly-pio-mode
  :hostmode 'poly-pio-hostmode
  :innermodes '(poly-pio-c-innermode))

(add-to-list 'auto-mode-alist '("\\.pio$" . poly-pio-mode))

There is a bug in this code. The poly-pio-c-innermode symbol should be defined using define-innermode instead of define-auto-innermode, since the latter expects a :mode-matcher which isn't provided (nor necessary). See the documentation of pm-inner-auto-chunkmode (used by the former), opposed to pm-inner-chunkmode (used by the latter).

Without this change, Emacs would print the following warnings:

error in polymode-post-command: (pm-switch-to-buffer 89): Unbound slot: pm-inner-auto-chunkmode, "#<pm-inner-auto-chunkmode pio-c>", mode-matcher, oref
Error during redisplay: (poly-lock-function 1) signaled (unbound-slot pm-inner-auto-chunkmode "#<pm-inner-auto-chunkmode pio-c>" mode-matcher oref)
Error during redisplay: (poly-lock-function 88) signaled (unbound-slot pm-inner-auto-chunkmode "#<pm-inner-auto-chunkmode pio-c>" mode-matcher oref)
Error during redisplay: (poly-lock-function 169) signaled (unbound-slot pm-inner-auto-chunkmode "#<pm-inner-auto-chunkmode pio-c>" mode-matcher oref)
[...]
Error during redisplay: (poly-lock-function 1) signaled (unbound-slot pm-inner-auto-chunkmode "#<pm-inner-auto-chunkmode pio-c>" mode-matcher oref)
Error during redisplay: (poly-lock-function 88) signaled (unbound-slot pm-inner-auto-chunkmode "#<pm-inner-auto-chunkmode pio-c>" mode-matcher oref)
Error during redisplay: (poly-lock-function 169) signaled (unbound-slot pm-inner-auto-chunkmode "#<pm-inner-auto-chunkmode pio-c>" mode-matcher oref)
error in polymode-post-command: (pm-switch-to-buffer 89): Unbound slot: pm-inner-auto-chunkmode, "#<pm-inner-auto-chunkmode pio-c>", mode-matcher, oref
Error during redisplay: (poly-lock-function 1) signaled (unbound-slot pm-inner-auto-chunkmode "#<pm-inner-auto-chunkmode pio-c>" mode-matcher oref)
Error during redisplay: (poly-lock-function 88) signaled (unbound-slot pm-inner-auto-chunkmode "#<pm-inner-auto-chunkmode pio-c>" mode-matcher oref)
Error during redisplay: (poly-lock-function 1) signaled (unbound-slot pm-inner-auto-chunkmode "#<pm-inner-auto-chunkmode pio-c>" mode-matcher oref)
Error during redisplay: (poly-lock-function 88) signaled (unbound-slot pm-inner-auto-chunkmode "#<pm-inner-auto-chunkmode pio-c>" mode-matcher oref)
Error during redisplay: (poly-lock-function 169) signaled (unbound-slot pm-inner-auto-chunkmode "#<pm-inner-auto-chunkmode pio-c>" mode-matcher oref)

Furthermore, I would edit the values of :head-mode and :tail-mode so they are not highlighted using asm-mode syntax; I changed it to 'poly-head-tail-mode. The full definition is:

(define-innermode poly-pio-c-innermode
  :mode 'c-mode
  :head-matcher "^% c-sdk {$"
  :tail-matcher "^%}$"
  :head-mode 'poly-head-tail-mode
  :tail-mode 'poly-head-tail-mode)

For example:

@8dcc thanks for the tips!

Since then, I have written a pio-mode package, which contains a major mode that is derived from asm-mode but only with the instructions specified by Raspberry Pi in their datasheets. In case someone is interested: 8dcc/pio-mode.el.