util: put convenience helpers into util.[ch]

Also introduces get_ncpus(), in preparation for threaded rendering.

2 files changed, 48 insertions, 0 deletions

diff --git a/util.c b/util.c
new file mode 100644
index 0000000..c07589e
--- /dev/null
+++ b/util.c
@@ -0,0 +1,22 @@
+#include <limits.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "util.h"
+
+#define SYSFS_CPU	"/sys/devices/system/cpu/cpu"
+#define MAXCPUS		1024
+
+unsigned get_ncpus(void)
+{
+	char		path[cstrlen(SYSFS_CPU "1024") + 1];
+	unsigned	n;
+
+	for (n = 0; n < MAXCPUS; n++) {
+		snprintf(path, sizeof(path), "%s%u", SYSFS_CPU, n);
+		if (access(path, F_OK) == -1)
+			break;
+	}
+
+	return n == 0 ? 1 : n;
+}
diff --git a/util.h b/util.h
new file mode 100644
index 0000000..c82b623
--- /dev/null
+++ b/util.h
@@ -0,0 +1,26 @@
+#ifndef _UTIL_H
+#define _UTIL_H
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define exit_if(_cond, _fmt, ...) \
+	if (_cond) { \
+		fprintf(stderr, "Fatal error: " _fmt "\n", ##__VA_ARGS__); \
+		exit(EXIT_FAILURE); \
+	}
+
+#define pexit_if(_cond, _fmt, ...) \
+	exit_if(_cond, _fmt ": %s", ##__VA_ARGS__, strerror(errno))
+
+#define nelems(_array) \
+	(sizeof(_array) / sizeof(_array[0]))
+
+#define cstrlen(_str) \
+	(sizeof(_str) - 1)
+
+unsigned get_ncpus(void);
+
+#endif /* _UTIL_H */