Sanitize altivec code so it can be built with runtime check properly

Originally committed as revision 10640 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 95 insertions, 0 deletions

diff --git a/libavcodec/ppc/check_altivec.c b/libavcodec/ppc/check_altivec.c
new file mode 100644
index 0000000000..72b4afe48a
--- /dev/null
+++ b/libavcodec/ppc/check_altivec.c
@@ -0,0 +1,95 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+
+/**
+ * @file check_altivec.c
+ * Checks for AltiVec presence.
+ */
+
+#ifdef __APPLE__
+#include <sys/sysctl.h>
+#elif __AMIGAOS4__
+#include <exec/exec.h>
+#include <interfaces/exec.h>
+#include <proto/exec.h>
+#else
+#include <signal.h>
+#include <setjmp.h>
+
+static sigjmp_buf jmpbuf;
+static volatile sig_atomic_t canjump = 0;
+
+static void sigill_handler (int sig)
+{
+    if (!canjump) {
+        signal (sig, SIG_DFL);
+        raise (sig);
+    }
+
+    canjump = 0;
+    siglongjmp (jmpbuf, 1);
+}
+#endif /* __APPLE__ */
+
+/**
+ * This function MAY rely on signal() or fork() in order to make sure altivec
+ * is present
+ */
+
+int has_altivec(void)
+{
+#ifdef __AMIGAOS4__
+    ULONG result = 0;
+    extern struct ExecIFace *IExec;
+
+    IExec->GetCPUInfoTags(GCIT_VectorUnit, &result, TAG_DONE);
+    if (result == VECTORTYPE_ALTIVEC) return 1;
+    return 0;
+#elif __APPLE__
+    int sels[2] = {CTL_HW, HW_VECTORUNIT};
+    int has_vu = 0;
+    size_t len = sizeof(has_vu);
+    int err;
+
+    err = sysctl(sels, 2, &has_vu, &len, NULL, 0);
+
+    if (err == 0) return (has_vu != 0);
+    return 0;
+#else
+/* Do it the brute-force way, borrowed from the libmpeg2 library. */
+    {
+      signal (SIGILL, sigill_handler);
+      if (sigsetjmp (jmpbuf, 1)) {
+        signal (SIGILL, SIG_DFL);
+      } else {
+        canjump = 1;
+
+        asm volatile ("mtspr 256, %0\n\t"
+                      "vand %%v0, %%v0, %%v0"
+                      :
+                      : "r" (-1));
+
+        signal (SIGILL, SIG_DFL);
+        return 1;
+      }
+    }
+    return 0;
+#endif /* __AMIGAOS4__ */
+}
+