From a936475949e45df42a2f60bf6d4b1f9978ba8468 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Sun, 8 Mar 2009 00:45:45 +0000
Subject: [PATCH] Comments to indicate where memory barriers may be needed.
Originally committed as revision 17867 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
libavutil/fifo.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/libavutil/fifo.c b/libavutil/fifo.c
index 4bc8be07ff1..8436b3b6a44 100644
--- a/libavutil/fifo.c
+++ b/libavutil/fifo.c
@@ -91,6 +91,7 @@ int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void
memcpy(f->wptr, src, len);
src = (uint8_t*)src + len;
}
+// Write memory barrier needed for SMP here in theory
f->wptr += len;
if (f->wptr >= f->end)
f->wptr = f->buffer;
@@ -103,6 +104,7 @@ int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void
int av_fifo_generic_read(AVFifoBuffer *f, int buf_size, void (*func)(void*, void*, int), void* dest)
{
+// Read memory barrier needed for SMP here in theory
do {
int len = FFMIN(f->end - f->rptr, buf_size);
if(func) func(dest, f->rptr, len);
@@ -110,6 +112,7 @@ int av_fifo_generic_read(AVFifoBuffer *f, int buf_size, void (*func)(void*, void
memcpy(dest, f->rptr, len);
dest = (uint8_t*)dest + len;
}
+// memory barrier needed for SMP here in theory
av_fifo_drain(f, len);
buf_size -= len;
} while (buf_size > 0);
--
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