control: socket-based debug channel + gbctl CLI driver

Replace the input-only FIFO's limitations with a Unix-domain socket control
channel (--sock) that is a superset of the button vocabulary plus emulator
introspection: read/write bus memory, get/set CPU context, single-step, PC
breakpoints, value-change watchpoints, run/pause. Being a socket it replies to
each command and broadcasts async 'event stop ...' lines; a stored last-stop
record (stopinfo) lets per-request clients recover a missed event.

Add gbctl: a stdlib-python CLI that spawns a tmux pane running the emulator on
a ROM, auto-resolves the socket, and drives it with terse verbs (cpu/read/write/
reg/step/break/watch/continue/pause/press/hold/screen/stop). The FIFO stays as
legacy input-only.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/render.h b/src/render.h
index 3b6c7e4..03d6c7c 100644
--- a/src/render.h
+++ b/src/render.h
@@ -8,6 +8,9 @@ void term_restore(void);
 void render_frame(GB *gb);
 void render_force_full(void);   // force a complete repaint next frame
 void render_set_hud(int frameskip, bool turbo);  // update HUD readout
+// Switch terminal output to sixel graphics (scale = integer pixel zoom, >=1).
+// Pass on=false to use the default Unicode half-block renderer.
+void render_set_sixel(bool on, int scale);
 // Poll keyboard + control FIFO, update gb->buttons. False if quit requested.
 bool input_poll(GB *gb);
 
@@ -16,6 +19,11 @@ bool input_poll(GB *gb);
 void input_open_fifo(const char *path);
 void input_close_fifo(void);
 
+// Process one line of button-command tokens (the FIFO/socket input vocabulary:
+// a b start select up down left right; name:N; +name / -name; release). Shared
+// by the FIFO and the richer socket control channel.
+void input_handle_command(const char *line);
+
 // Returns true once for each pending fast-forward (turbo) toggle keypress.
 bool input_take_turbo(void);
 // Net frameskip adjustment requested via '[' / ']' since last call.