input: external control channel via FIFO

Adds --fifo [path] opening a named pipe that accepts button commands from any
process. Supports momentary taps (a, start, name:N), deterministic hold/release
(+name / -name), and 'release'. Merges with keyboard input; held state carries
true key-up semantics the terminal can't provide. GBC_INPUT_DEBUG traces state.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/main.c b/src/main.c
index 273d6b7..173ab5b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -34,6 +34,7 @@ int main(int argc, char **argv) {
     double seconds = 30.0;
     int shot_frames = -1;
     const char *shot_path = "shot.ppm";
+    const char *fifo_path = NULL;
     for (int i = 2; i < argc; i++) {
         if (!strcmp(argv[i], "--test")) {
             test = true;
@@ -41,6 +42,9 @@ int main(int argc, char **argv) {
         } else if (!strcmp(argv[i], "--shot")) {
             if (i + 1 < argc) shot_frames = atoi(argv[++i]);
             if (i + 1 < argc && argv[i+1][0] != '-') shot_path = argv[++i];
+        } else if (!strcmp(argv[i], "--fifo")) {
+            fifo_path = (i + 1 < argc && argv[i+1][0] != '-')
+                        ? argv[++i] : "/tmp/gbc.fifo";
         }
     }
 
@@ -72,6 +76,11 @@ int main(int argc, char **argv) {
 
     signal(SIGINT, on_sig);
     signal(SIGTERM, on_sig);
+    if (fifo_path) {
+        input_open_fifo(fifo_path);
+        fprintf(stderr, "control fifo: echo 'a' > %s   (a b start select "
+                "up down left right; +x/-x hold/release; release)\n", fifo_path);
+    }
     term_init();
 
     const double frame_time = 1.0 / 59.73;
@@ -93,6 +102,7 @@ int main(int argc, char **argv) {
     }
 
     term_restore();
+    input_close_fifo();
     cart_free(&gb->cart);
     free(gb);
     return 0;