spa/support: implement ARM CPU detection

Code is based on PulseAudio's implementation, originally written by Wim

spa/plugins/support/cpu-arm.c

@@ -0,0 +1,123 @@
+/* Spa
+ *
+ * Copyright © 2019 Wim Taymans
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#define MAX_BUFFER 4096
+
+static char *get_cpuinfo_line(char *cpuinfo, const char *tag)
+{
+	char *line, *end, *colon;
+
+	if (!(line = strstr(cpuinfo, tag)))
+		return NULL;
+
+	if (!(end = strchr(line, '\n')))
+		return NULL;
+
+	if (!(colon = strchr(line, ':')))
+		return NULL;
+
+	if (++colon >= end)
+		return NULL;
+
+	return strndup(colon, end - colon);
+}
+
+static char *get_cpuinfo(void)
+{
+	char *cpuinfo;
+	int n, fd;
+
+	cpuinfo = malloc(MAX_BUFFER);
+
+	if ((fd = open("/proc/cpuinfo", O_RDONLY | O_CLOEXEC, 0)) < 0) {
+		free(cpuinfo);
+		return NULL;
+	}
+
+	if ((n = read(fd, cpuinfo, MAX_BUFFER-1)) < 0) {
+		free(cpuinfo);
+		close(fd);
+		return NULL;
+	}
+	cpuinfo[n] = 0;
+	close(fd);
+
+	return cpuinfo;
+}
+
+static int
+arm_init(struct impl *impl)
+{
+	uint32_t flags = 0;
+	char *cpuinfo, *line;
+	int arch;
+
+	if (!(cpuinfo = get_cpuinfo())) {
+		spa_log_warn(impl->log, NAME " %p: Can't read cpuinfo", impl);
+		return 1;
+	}
+
+	if ((line = get_cpuinfo_line(cpuinfo, "CPU architecture"))) {
+		arch = strtoul(line, NULL, 0);
+		if (arch >= 6)
+			flags |= SPA_CPU_FLAG_ARMV6;
+		if (arch >= 8)
+			flags |= SPA_CPU_FLAG_ARMV8;
+
+		free(line);
+	}
+
+	if ((line = get_cpuinfo_line(cpuinfo, "Features"))) {
+		const char *state = NULL;
+		char *current = strtok_r(line, " ", &state);
+
+		do {
+#if defined (__aarch64__)
+			if (!strcmp(current, "asimd"))
+				flags |= SPA_CPU_FLAG_NEON;
+			else if (!strcmp(current, "fp"))
+				flags |= SPA_CPU_FLAG_VFPV3 | SPA_CPU_FLAG_VFP;
+#else
+			if (!strcmp(current, "vfp"))
+				flags |= SPA_CPU_FLAG_VFP;
+			else if (!strcmp(current, "neon"))
+				flags |= SPA_CPU_FLAG_NEON;
+			else if (!strcmp(current, "vfpv3"))
+				flags |= SPA_CPU_FLAG_VFPV3;
+#endif
+		} while ((current = strtok_r(NULL, " ", &state)));
+
+		free(line);
+	}
+
+	free(cpuinfo);
+
+	impl->flags = flags;
+
+	return 0;
+}

spa/plugins/support/cpu.c

@@ -51,6 +51,9 @@ struct impl {
 # if defined (__i386__) || defined (__x86_64__)
 #include "cpu-x86.c"
 #define init(t)	x86_init(t)
+# elif defined (__arm__) || defined (__aarch64__)
+#include "cpu-arm.c"
+#define init(t)	arm_init(t)
 #endif
 
 static uint32_t