Start work on a choose kitten for fuzzy selection

kittens/choose/unix_compat.c

@@ -0,0 +1,50 @@
+/*
+ * unix_compat.c
+ * Copyright (C) 2017 Kovid Goyal <kovid at kovidgoyal.net>
+ *
+ * Distributed under terms of the GPL3 license.
+ */
+
+#include "choose-data-types.h"
+#include <unistd.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+#ifdef __APPLE__
+#ifndef _SC_NPROCESSORS_ONLN
+#define _SC_NPROCESSORS_ONLN 58
+#endif
+#endif
+
+int
+cpu_count() {
+    return sysconf(_SC_NPROCESSORS_ONLN);
+}
+
+
+void*
+alloc_threads(size_t num_threads) {
+    return calloc(num_threads, sizeof(pthread_t));
+}
+
+bool
+start_thread(void* threads, size_t i, void *(*start_routine) (void *), void *arg) {
+    int rc;
+    if ((rc = pthread_create(((pthread_t*)threads) + i, NULL, start_routine, arg))) {
+        fprintf(stderr, "Failed to create thread, with error: %s\n", strerror(rc));
+        return false;
+    }
+    return true;
+}
+
+void
+wait_for_thread(void *threads, size_t i) {
+    pthread_join(((pthread_t*)(threads))[i], NULL);
+}
+
+void
+free_threads(void *threads) {
+    free(threads);
+}