macOS/Apple Silicon port: NEON kernels + platform shim (PR #1 by RDouglasSharp)

c/st.h

@@ -15,6 +15,7 @@
 #include <unistd.h>
 #include <dirent.h>
 #include "json.h"
+#include "compat.h"
 
 typedef struct {
     char   *name;
@@ -78,7 +79,13 @@ static int st_open_fd(shards *S, const char *path) {
     int fd = open(path, O_RDONLY);
     if (fd < 0) { perror(path); exit(1); }
     S->paths[S->nfd] = strdup(path); S->fds[S->nfd] = fd;
+#ifdef O_DIRECT
     S->dfds[S->nfd] = open(path, O_RDONLY | O_DIRECT);   /* eager: lookup poi thread-safe */
+#elif defined(__APPLE__)
+    S->dfds[S->nfd] = compat_open_direct(path);          /* macOS: F_NOCACHE ~ O_DIRECT */
+#else
+    S->dfds[S->nfd] = -1;                                /* niente equivalente: solo buffered */
+#endif
     S->nfd++;
     return fd;
 }